1 10 13181 https://digitalcollections.lakeheadu.ca/files/original/6e708ac190d9ce3a7fc614a501f1a3e6.pdf 8c7c0e8fbb4b9d69f050bc1bc219485d PDF Text Text ���� Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Lakehead University Collection Description An account of the resource Photographs from Lakehead University's history: people, events, and campus. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Lakehead University Convocation Programme 2026 Subject The topic of the resource Universities Description An account of the resource Lakehead University 61st Convocation Programme 2026. Creator An entity primarily responsible for making the resource Lakehead University Format The file format, physical medium, or dimensions of the resource PDF Type The nature or genre of the resource Text Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada - Ontario - Thunder Bay Date A point or period of time associated with an event in the lifecycle of the resource 2026 Language A language of the resource English Identifier An unambiguous reference to the resource within a given context Convocation2026 https://digitalcollections.lakeheadu.ca/files/original/48f4e4d93a4d11a10cb8224e7237b8b9.pdf 02e38dde3cc30fe7a3e3545a5d1b67bf PDF Text Text iversity Alumni a 'Lori-Ann Newman liAVlNO COl,IPl.&Tl!D 'nfll REQUIIU!D COURSl!S OP STtlDY AND HAVINOCOMPUED WITH AU,OTHER REQUIRllMEN'lS OFTI<8 IJNl\"E1!Sfl'Y, IS HllRSSY /\WMDl!D 'l'he D'egree of Bachelor of Arts g·(dre of IN~ONYWHBRiOFWl!HAVBI\FPIXl!DOUllS10NA11JII.ES , AND THI! SEAL OF nm U\i!YlillSITY /4111,~ ~ ·.w "'r. -.iif!£ ~ ~ ADDRESS, CITY POSTAL CODE, DATE, PAYMENT PH= SIGNATIJRE· O I ENCLOSE CHEQUE MADE PAYABLE TO THE ALUMNI ASSOCIATION OF LAKEHEAD UNIVERSITY 0 MASTERCARD O VISA CARD NUMBER EXPIRY DATL llESCRI PTION PRICE 1991 GRADS AND LATER SHOULD ORDER SIZE ll"Xl5" WITH MATT $52.00 DIPLOMA FRAMES 1990 GRADS AND EARLIER SHOULD ORDER SIZE I l"Xl4" WITH MATT $42.00 PORTRAIT FRAMES 1l"X14" IV/MATT FOR S"XI0" PHOTO S42.00 S"XIO" IV/MATT FOR i"Xl" PHOTO $32.00 SUB TOTAL INSURED SHIPPING AND HANDLING (CANADA) CANADIAN RESIDENTS ADD l'X, G.S.T. $i.5ll TOTAL • Trojan ternal Relations ONTARIO RESIDENTS ADD 8% P.S.T. ..,,, �Qcy. Item Face Black Tora! Gold Men's Watch (Black Band) UIUJnrrn Summer 1996, Volume 13 Number 2 Men's Watch (Brown Band) AMagazine for Lakehead University Alumni and Friends Nor'Wester Editorial Committee Women's Watch (Black Band) David Heald '84 Nancy Adderley '90 Nancy Angus '81 Vonnie Cheng '80,'82,'92 Ben Kaminski '82 Janet Fuchek '87,'88 Julio Gomes '86 Lynne Peters '78,'82,'92 Dinah Waddell '73,'75,'85 Women's Warch (Brown Band) Total --Ont. residents 80/oPST Postage & Handling ~ Total Order _ _ _ Nam e Address Editor Postal Code Telephone D D Cheque or Money Order VI SA □ Masrercard Card No. Frances Harding Tel: (807) 343-8193 E-mail: frances.harding@lakeheadu.ca Editorial Assistant Betty Hygaard Photography Peter Puna Valid Date _ _ _ _ Expiry Date Barry Smith & Associates Graphic Design Signature Mail co: LAKEHEAD UNIVERSITY ALUMNI, c/o Dave Douglas Jewellers, 200 Red River Rd ., Thunder Bay, Ontario, Canada, P7B I A4, or call 1-800-465-2207 The Alumni Association of Lakehead University Board of Directors President: Jim Kalyta '82 President-Elect: John Friday '81 Treasurer: Mark Tilbury '94 Past President: Bill Banky '72 Board of Governors Representative: (1994-97) Joseph R.Barana '70,'75,'80 Board of Governors Representative: (1997-2000) Betty C. Coates '69 Members-at-Large: David Heald '84 Ben Kaminski '82 Lynne Peters '78,'82,'92 Mary Sacco '87 Ex- Officio Member Chris Straka, LUSU President The Financial Concept Group invites Lakehead • No annual fees. • No acquisition fees. For more information on this and other income building investment University alumni to explore this outstanding • One of Canada's largest investment opportunity. investment managers, Bob Thompson. This exclusive group RRSP with over $12 billion (807) 345-0200 or with the respected pro- under administration. opportunities please call 1-800-880-1424 Director of Student Services and Community Relations Joy Himmelman Manager of Alumni Services Rob Zuback '88 Alumni Assistant fessional management of Mackenzie Financial Corporation is available with: Mackenzie Building Financial Independence cO'n~t Group Address correspondence to: Financial Concept is. a licensed Mutual Fund Dealer. F.C.G. Securities Corporation is a licensed Securities dealer. am .Ho!l~i U1 Bfoim'96 By Dinah Waddell, BA'73, BEd'75, MEd'85 When Adam Molai returns to Zimbabwe in September, he plans to start a business that will allow him to spend more time on his real passion - business consulting. "My heart is in business consulting on any scale," he says . "It is a joy to work with entrepreneurs who have an idea, and then to see the business actually running." Home for this international student is Marondera, Zimbabwe, south of the capital city Harare. After graduating from an Anglican boarding school, Molai spent a year studying business at the University of Buckingham in London, England, before looking through the calendars of Canadian universities in search of a new experience. He was delighted to receive his first response from Lakehead. "I couldn't have made a better choice," he says. Extra-curricular activities have included being advertising manager for the student newspaper, working as a telemarketer during the Alumni Association's annual fund-raising campaign, and serving as President of the African-Caribbean Students Association. But throughout, his overriding interest has been the Lakehead University Management Consulting Service where students, supervised by faculty, provide marketing management, strategic management, financial management, hardware and software expertise, and training courses to small and medium-sized businesses in Northwestern Ontario. As Senior Manager for the last three years, Molai has watched with pride as more than 50 business students involved with the Se rvice have since found full-time employment. During Molai's third and fourth years at Lakehead, he participated in the Queen's Intercollegiate Business Competition, a race that has come to be known as the "Stanley Cup of business schools." (continued on page 19) Kristine Carey The Nor'Wester is published three times a year by the Department of External Relations in cooperation wi th the Alumni Association of Lakehead Universny. The views exp ressed or implied in the magazine do not necessarily reflect those of the Alumni Association or Lakehead University. To update your alumni record, please call: -·1 Office of Alumni Services Lakehead University 955 Oliver Road Thunder Bay, Ontario P7B 5El Tel: (807) 343-8155 Fax: (807) 343-8999 E-mail: frances.harding@lakeheadu.ca Nor'Wester Department of Student Servic~s and Community Relations Lakehead University 955 Oliver Road Thunder Bay. Ontaiio P7B SE I. 2 IUE Toward the Next Millennium A discussion on the challenges facing universities in light of government cutbachs 4 Jane Taylor Placing Lahehead students in the community 7 Back to the Future Bob Rosehart on the increased role for alumni 8 Campus News 10 Report from the Board 12 Calendar of Events 14 Class News To Enquire about Advertising, please contact the Editor. Nor'Wester 1 �Kerrie-Lee Clarke Special AssistanVlnstitutional Research to the Vice-President, Academic owa David Euler Dean, Faculty of Forestry Livio Di Matteo Economics Professor • Part Two DflllO In the last issue of the Nor'Wester, we introduced you to a panel of Sher Ali Mirza Engineering Professor Randy Nelsen Sociology Professor seven ilakehead University faculty and staff members who had gathered last November to discuss the critical issues facing universities. Part One focussed on the value of a liberal arts education Connie Nelson Dean, Graduate Studies and Research and the difficulties universities have in marketing scholarship. Part Two looks a t the effect of tne university funding crisis on teaching and research. Our thanks go to Qavid Heald (BA'84) who served as moderator and Nancy Adderley (HBA '90) who taped and, edited the panelists' comments. 2 Nor'Wester Laure Paquette Political Science Professor Technology and the Liberal Arts Education Q: What the politicians may want and what the leaders of corporations may want could be drastically different from what society as a whole may need. Can you speak to this conflict between the value of a liberal arts education and the need for technical expertise? Kerrie-Lee Clarke: "I really think that the politicians and civil servants are saying that we have to prepare people for this uncertain future and part of that is having some basic skills, a lot of which are going to come out of a liberal arts education. But we also have to have the technical skills as well. Education is the foundation on which society is built. Society as we know it is built on the information and discoveries that have been made in universities, and unless we can get that message out, I think we're really going to be in trouble ." Connie Nelson: "What makes it so traumatic is that there are a number of issues facing universities at precisely the time that money is tight. The potential of technology to redefine the way we even approach the topic of learning is hitting universities head on. We are just tiptoeing to the door of dealing with this issue . It is not just an issue of delivering what we already know - the technology makes all kinds of new knowledge available to us, and we don't know how we are going to deal with this." Laure Paquette: "The question that we are facing therefore, is what do we teach 1 For those of us in the social sciences, I don't need to tell students what the Canadian Constitution is anymore, they will be able to get that off the Internet instantly. I have to teach them the Internet is a dramatically uneven quality of information. I have to teach them how to judge that. So it's a question of not the content of what we teach, but what skills are we going to teach . And we can't strictly focus on the needs of the private sector, because that is a moving target." Livia Di Matteo: "If this information revolution - this technological change - is really going to change Lhe way we do things, you have to look at what is most easily automated at a universiLy. And l guess what is most easily auLOmated is probably a large portion of the teaching. However, it is still difficult to automate research. The crucial role for a university might become more heavily focussed on research. So if you are looking at what a university is going to evolve into over time, there are two possible models. We could go around teaching skills - how to access the Internet, how to work a spreadsheet. Or we could go around attracting quality faculty, creating a research environment where you generate new knowledge. So, should the university become a destination point on the information highway, sort of a critical mass of scholars doing research and disseminating it, or are we going to just provide the "drivers' ed." courses?" Research and Teaching: In Search of the Best Blend Q: What are the pressures facing universities right now in terms of research? Sher Ali Mirza: "In the professional faculty, the faculty members are tremendously underpaid, especially the younger ones. Coming soon, perhaps we will get salary cuts, and if that happens, we are going to see some of our younger, brighter faculty members taking off for industry. At this point, the faculty is aging and unless you bring in new blood, how is the renewal going to take place? Some of our faculty members are working 60 to 80 hours a week. There comes a point where they have to slow down because age catches up with them . And when that happens, their research is going to slip. Without new people to replace them, quality has to go down. In order for a faculty member to , be energetic and provide up-to-date knowledge, to get a "spark" inside himself or herself, he or she has to do research. He or she has to be at the cutting edge of knowledge ." Connie Nelson: "We have typically viewed ourselves as an undergraduate institution, so we have hired to meet a breadth of needs. But I think there is a growing feeling out there that anybody who has a PhD should, for the most part, be able to teach the basic core concepts of their discipline regardless of what their specialization was . If we changed our thinking, we could hire in a way that would allow us to take these resources and do advanced training at the same time as we provide an undergraduate education. The outcome would be quite exciting." Laure Paquette: "Professors are hired to teach certain courses and to do research into a particular specialty. Traditionally, there has been a link in that you teach in your specialty. What Connie is suggesting is instead of doing that, let's get people who are very good and let's concentrate - get a critical mass of researchers in a particular area, knowing full well that they can teach the spectrum of undergraduate courses. She's proposing this in the broader framework of a very important issue - what is the relationship between teaching and research. This relationship is going to come under heavy fire with all the budget cuts and all the changes that we foresee. " Intellectual Freedom? Q: Will the shift in funding priorities compromise the standing principle of maintaining the administrative and intellectual freedom our institutions need? Randy Nelsen: "The administrative and intellectual freedom, particularly the intellectual freedom, has already been well-compromised before any budget cuts ... In terms of the budget cuts, what is already in pretty bad shape is going to get worse . Increasingly, we are going to have to find ways to raise our own money. So we are going to become more privatized, more like private entrepreneurs. I'm critical of this entrepreneurial system, and this university/big business partnership, because it takes us more into the system and doesn't allow us to stay at arm's length in a way that would allow us to remain critical. Q: Is there any danger in a university becoming too closely associated with corporations, in order to receive funding dollars? David Euler: "In our faculty (Forestry), we have people who are critical of corporate practices and we have people who support corporate practices. Naturally, the corporations, being self-interested, begin to support those faculty who support the things they do. That's a real problem - how to maintain this freedom to say what we think is right, in the face of incredible budget cuts." D Nor'Wester 3 �strategies and language for social competency, and an adapted physical activity program in the gymnasium which gives the participants an opportunity to apply their new skills in a recreational setting. "I see my role as encouraging partnerships and providing the opportunity for growth and change to occur," says Taylor. "These programs are not a quick fix to self-esteem In Partnership with the Community By Wendy Bourke for children who are excluded and rejected by their peers. Sometimes when a child has success in the clinic, the real gain is that people who had previously gi ven up, begin to Jane Taylor's work is a testament to the good things that can work together again. " be accomplished when educators, government, volunteers and Everyone benefits when the program works well and students are often profoundly stakeholders act together. Each year this Kinesiology professor finds affected by the experience . According to Education student Sharon Askes, "Practical placements for approximately 100 students in hospitals, schools and experience opens your eyes to what's going on out there , in a way that classwork never service agencies throughout Northwestern Ontario. In fact, there are many Lakehead University faculty like Taylor who are strengthening services across the region by their teaching and research. brother Bruce, who has cerebral palsy, has The Thunder Bay Clinic teams fourth-year Kinesiology students with children who have various motor skill problems . lts purpose is to give children who typically do not succeed the opportunity to develop excel- had a lot to do with the way my life's work lence or at least adequacy in a skill. When speaking with Jane Taylor it quickly becomes apparent she has an innate sensiti vity and respect for people with disabilities. "I think my relationship with my has unfolded," she says. students with learning disabilities in London , Ontario. It was there she realized in the rest of a child 's life . Physically awkward children often exempted them- Placing and monitoring students in "real" selves or were excluded from activities, and situations takes tremendous commitment and effort on the part of busy faculty, but in doing so, paid a terrible price in terms of of Alberta, Taylor developed the criteria she would later use to e valuate motor skill issues . Under the guidance of her thesis In addition to operating the Motor Development Clinic, Taylor helped develop giving sLudents this practical experience while benefiting others is showing itself to and operate a Social Skills/Recreation Program in conjunction with Dr. Fred Schmidt, a psychologist at the Lakehead be well wonh it. Sa ys Taylor : "You can'L learn enough about people with disabilities advisor, Dr. Ted Wall, she opened the first Motor Development Clinic in Edmonton in Regional Family Centre. The Social Skills/Recreation Program (initiated by the Learning Disabilities Association) has 1981. Ten years later, she opened another one in Thunder Bay. two pans: a social skills component in the classroom which centres on appropriate 4 Nor'Wester years, Lakehead students have worked with more than 25 agencies including St. Joseph's Hospital, both local school boards , the George Jeffrey Children 's Treatment Centre, students have spent many hours assisting at local homes for seniors such as Bethammi and Grandview, keeping the elderly active. how recreation mirrored what was going on While pursuing her studies at the University appreciate the practicum process as an important resource, and they value the effort and enthusiasm of the students. Over the Joseph's Hospital Reactivation Unit and the Thunder Bay Therapeutic Riding Association. As well, Taylor's undergraduate physical education teacher at a school for well-being and level of fitness. As budgets are cut, more and more agencies Special Olympics , Superior Athletics , St. Taylor began her career as a high school their social skills development, emotional could. When you see what you're doing is making a difference, it 's a wonderful feeling." in a lecture selling. The whole premise of the adapted program is based on inLeraction. Without mutual respect, tolerance and knowing that we are striving for the same goals, our own programs could noL flourish ." 0 �CUSTOM IMPRINTED OR EMBROIDERED . •e )I ! ~ •• ,, ~ SWEATSHIRT T-SHIRTS JACKETS HATS 308 Memorial Avenue, Thunder Bay, Ontario, P7B 3Y2 Phone: (807) 345-3011 Toll Free: (800) 446-4310 Fax: (807) 344-1469 You can apply for up to $930,000 in total Term Life Insurance and Accidental Death & Dismemberment coverage for you and your spouse. PLUS up to $10,000 in Life coverage for each of your dependent children. Enjoy the lowest premiums possible through the group buying power of your Alumni Association. And NON-SMOKERS are entitled to substantial discounts! $930,000 - - u ersp,ertiVie "Back to the Future" The Increased Role for Alumni By Dr. Robert G. Rosehart, President, Lakehead University During this past year, the Ontario government has reduced operating grants to Ontario's public universities by more than 15 percent in one year. This is unprecedented and places Ontario's funding per university student as the lowest in Canada. In these most turbulent times, the title "Back to the Future" is really meant to imply that we need to look back increasingly to our alumni to help our future students at Lakehead University. The question often asked by the public is "has there been a consensus developed around a fundamental shift in the value of a publicly-funded education system?" Although the long-standing argument in favour of a publicly-funded system stands today unchallenged, the recent practice in Ontario seems to signal a shift in the "Personal Benefit-Public Investment" equation. With the group purchasing power of your University Alumni Association Public Personal Benefit Investment W _ __,\:.>-- non-existent. These issues will, no doubt, be debated when the Ontario government releases its long-awaited "White Paper" on post-secondary education. Accessibility and affordability are questions the public needs to be increasingly focussed upon. One thing is certain about the future; it will not be like the past. In order to look to the future, it is useful to reflect upon where we have come from, and you may find the comparisons in the tables below of interest. Several numbers stand out, and I have noted two with an asterisk. It is clear that, particularly in the 1984-1996 period, tuition fees have really escalated, to almost three times the 1984 levels. During this time, we have seen a long period of recession and, generally, a tough summer job market for the students. As well, debt loads have increased, and the post-graduation job market has become increasingly competitive. Enough of the sobering past - the positive perspective is the significant increase in alumni giving to our Annual Fund, up by Dr. Robert G. Rosehart almost a factor of five from 1984. Your contributions are appreciated and will be even more important in the future as more of the financial burden of post-secondary education is moved to the students. This need is going to be particularly felt by students who need bursary support. The Ontario government, in its May, 1996 Budget, recognized that more student aid was needed in Ontario universities, and they are permitting each university to establish a special student aid (continued on page 19) LAKEHEAD UNIVERSITY'S GROWTH 1970 1984 1996 Student Body (Full-Time) 2,900 3,695 5,800 Budget (Millions) $7.5 $26.7 $48.1 Tuition $560 $1,174 $3,250 Residence/Food $1,035 $2,685 $4,600 Number of Alumni 1,654 12,303 25,278 How do we place some of the above in perspective? Let us !ooh at some of the relative changes: NCE BENEFITS Call today for more Information: 807-345-3444 Amethyst Financial Group Ltd. or Toll-Free 1-800-387-9223 Seaboard Life Insurance Company_ 6 Nor ' Wester RELATIVE CHANGE - LAKEHEAD UNIVERSITY A fundamental shift? Generally, society recognizes the value of a well-educated population to society as a whole, and it is widely recognized that a publicly-funded education system is one of the most effective social equalizers. For example, in the State of Georgia, lottery profits go to provide full tuition scholarships for worthy students and in Finland, one of our most progressive international competitors, tuition fees are 1970-1996 1984-1996 Student Body 2.0 1.6 Budget 6.4 1.8 Tuition 5.8 2.8· Residence/Food 4.4 1.7 House Cost (Tliunde,· Bay) 7.0 1.5 lncermediate Car Cost 6.3 1.8 Number of Alumni 15.2 2.1 lncremenral Alumni Giving (no fund) 4.S• Nor'Wester 7 �Eli~ S conjunction with the LU served by the three components: the Instrumentation Laboratory External Services, the Soils Laboratory and the Aquatic Toxicology Research Centre. Community Council, Norma has ensured that children feel good about Lakehead University Business Program Among the Best Lakehead may not have the largest business school in Canada, but when it comes to quality, there is no question it ranks among the top five this year. Four student teams made it to the final round of the Queen's Intercollegiate Business Competition, and Lakehead placed first in the Management Information Systems (MIS) category, beating out Calgary, Wilfrid Laurier, Carleton, Memorial and Queen's. Jamie. We had a wonderful and could see where their parents work," says Joy Himmelman, Director of Student Services and time! The Valhalla Inn was firstclass and the car rental worked Community Relations and Chair of the selection committee, "She out very well. We even went has made the campus a real place for families." Thunder Bay to visit our son, skiing on the Saturday in near perfect conditions . We were To Boldly Go very impressed with the campus When most people hear the words "high-tech" and "Lucas" together, they probably imagine something like Star Wars, the classic movie that gave us incredible special effects by and the attitude of the students. It is no wonder that you make it easy for parents to visit." For information contact Tourism Thunder Bay at 1-800-667-8386. '';, ~ ., ~· ;-:~ show equally strong levels of performance in the Certified Management Accountant (CMA) program in Ontario. Thumbs up for the LU Travel Program employment University students and gradu- ~~:~~~~-- , Although retiring this year, she'll Thunder Bay, has put together a travel package that is drawing be remembered as the first recipient of the Lake head praise from parents. Sandi University McCabe from London, Ontario, Recognition Award . "With the writes: "My husband and I took many summer picnics and advantage of the Canadian Holiday's package and came to Christmas and Halloween par- Community ties she has organized in Hensel (Engineering); Thomas Song North, Dennis Roddy, Murray Ian Hoodless (Chemistry); and Anita Chen (Sociology) . The Zimmermann Scholarship Ernst Zimmermann During his 29-year career at Lakehead, Zimmermann served as Chair of the Department of History, Dean of Arts, President Fund now totals over $12,000. If you wish to make a contribution, contact Jo-Anne Silverman at (807) 343-8910. of the Faculty Association, and The Will to Share member of both the Senate and the Board of Governors. RBC Dominion Securities and Among the many friends who spoke that evening was colleague Vic Smith who suggested Zimmermann's initials (E R.) second and third place at a might stand for Ernst Robert, provincial competition held on but they could just as easily campus this year. Director Ian Blanchard credits his team's stand for "extremely rambunctious," "excessively rude," success to the many hours "equally respectful," "energeti- spent in training alongside cally restive," and "entirely Thunder Bay's Emergency relentless." Lakehead University hosted a seminar on planned giving in May that was attended by more than 15 charitable organizations For details on life insurance and other planned giving options, please call or write: Vonnie Cheng Development Office Lakehead University 955 Oliver Road Thunder Bay, ON P7B 5El Tel: (807) 343-8913 Fax: (807) 343-8999 E-mail: Vonnie.Cheng@LakeheadU .Ca President of Lakehead Bob Thunder Bay Ambulance and Rosehart praised Zimmermann Thunder Bay Regional Hospital saying he was one of the origi- - McKellar Campus. The nal 'Team Lakehead' members, Emergency First Response team "committed, challenging, and provides around-the-clock first always interesting... an extreme- aid service for everyone on 1y dedicated teacher, and an ardent unionist." * THUNDER BAY SYMPHONY ORCHESTRA 1996/97 Season STEPHANE LAFOREST Music DIRECTOR & CONDUCTOR in Thunder Bay. Some people associate 'planned giving' with bequests, however there are MASTERWORKS many other instruments for POPS 0 0 planned giving. These include life insurance policies, gift annuities, and charitable remainder trusts. In the case of charitable Health Services which includes campus. Depending on the type of policy given, it may be possible for you to receive a charitable donation receipt for the cash value and insurance premium. (Education); Alan Hughes and Rotary Club are helping stu- Response Team earned first, For a modest monthly premium, you can provide much-needed financial assistance and educational opportunities to deserving students in the future. (Kinesiology); Peter Rutherford Members of the Lakehead Leading the Way Support Lakehead University's Scholarship & Award Program with a gift of life insurance. (Business Patterson, Martin Oosterveld Lakehead's Emergency First conjunction with the City of Maria Fine, Bill Honey and Building Confidence view skills. LUCAS brings together the expert technical staff, high quality researchers and cutting edge technology necessary to offer analytical testing and consulting services to government, industry and the scientific research community of Northwestern Ontario. These clients are (Forestry); Douglas Alexander, MacKenzie at (807) 343-8294. writing, and successful inter- INVEST FOR FUTURE GROWTH Farmer, and Tom Hazenberg David Hughes (Physics); Henry search strategy, effective resume with a cheery "Lake-head Un-i- Emil David, Robert Day, Robert and George Ozburn (Biology); Employment Readiness Program For the last 26 years, Norma Gibson has been greeting callers Recreation, Parks and Tourism); Andre Cloutier (Languages); offers tests accredited by the which included sessions on job Voice of Lakehead Retires (Outdoor Standards Council of Canada. For information call Allan interviews were part of a larger director George Lucas. But Lakehead University has an impressive LUCAS right here on campus with fascinating technology of its own: LUCAS is the Lakehead University Centre for Analytical Services. Thomson Administration); Richard Freitag operative Education Centre. The Norma Gibson Lisle Arthur Student Placement and Co- "",p.11 include: Henry Akervall and testing labs in Thunder Bay that ing skills. Last March volunteers ":~ Other faculty retiring this year ates, LUCAS is one of the few took part in mock interviews Lakehead University, working in Nor'Wester and offered by the University's ver-sity" from her post at the University's Switchboard. 8 training opportunities for Lakehead Retiring history professor Ernst Zimmermann was showered with good wishes at a fundraising dinner held in March to establish an endowment for an annual award to a senior student in history. dents brush up their interview- Lakehead graduates continue to perform with excellence in the professional educational programs offered by the professional accounting associations. Last year 10 out of 10 first-time writers were success[ ul in the Uniform Final Examinations for the Chartered Accountant designation in Ontario. As well, Lakehead students continue to Besides providing education, A Big Heart and a Brilliant Mind CANDLELIGHT 0 CLASSICAL 0 SPECIAL EVENTS gift annuities , the donor is able to make a gift and still receive tax free income. For more information contact Vonnie Cheng at (807) 343-8913. 0 CONCERTS FROM OCTOBER To APRIL '96 '97 Box OFFICE 343-2300 CALL THE Nor'Wester 9 �Report ro:m l~e Board MAJOR SPONSORS: This issue of the Nor'Wester comes to you as I begin my first year as President of the Alumni Association of Lakehead University The Board of Directors has accomplished much under the guidance of Past-president Bill Bartley, and we thank him for the hard work and leadership he has displayed during the last two years. In essence, the Board is undergoing a changing of the guard, but we will not be resting on our laurels for there are many projects in th e works. friends attended the Annual General Meeting in conjunction with our Volunteer Appreciation Evening on May 2, 1996. Dr. Bob Rosehart, the President of Lakehead, was the keynote speaker and he delivered an entertaining and informative talk on the future of Lake head University and the importance of its alumni . Thanks to all who attended and special thanks to Centra Gas Ontario Inc. who co-sponsored the Volunteer Appreciation dinner. I would also like to take this opportunity to congratulate and wel- Your new executive committee for 1996-97 is comprised of: Financial Concept Group & Trimark Mutual Funds CO-SPONSORS: Campbell & Company Insurance Brokers Ltd. Amethyst Financial Services Tilden lnterrent Thunder Bay Telephone LU Alumni Association LU Alumni Bookstore LU External Relations LU Intersection LU Print Shop Maltese Grocery Main River Company Mario's Bowl Mr. Lube PRIZE DONORS: Neebing RoadHouse A to Z Rentals AFG Glass Northern Exposures/Brodie Street Art Gallery Airlane Hotel Nor'Wester Resort Apex Investigation & Security Old Dutch Foods The Board of Directors has been busy over the course of the last few months setting goals and objectives for the future. Results from those meetings will be communicated to you in my next column, but if we could identify one main point that has resulted from our discussions, it is the fact that we continue to need the assistance and expertise of our alumni from all walks of life and professional backgrounds. If you are interested in becoming involved , please write to me care of the Alumni Services Office. Country Good Meats cial thanks to Joe for holding this position over the past three years . Vacancies At present, we are completing our Board development process and we invite interested alumni to join the Board. We currently have four vacancies which need appointments. If you think you might have skills to enhance the Board, please write to me or contact Rob Zuback , Manager, Alumni Annual General Meeting and Volunteer Appreciation Evening Se r\'ices. Approximately 60 alumni, volunteers and Have a great summer' D 10 Nor'Wester Barry Smith & Associates Beatrice Foods Beaver Lumber \ Marlin Travel Seaboard Life Insurance Co. A&A Records ' Minute Muffler come the graduating President: Jim Kalyta class of 1996 to the (BAdmin '82), PastAlumni Association . . . . president : Bill Bartley Jim Kalyta - President, Alumni Assooat,on Finally, after many (BA '72) , Presidentyears of hard work, you have been rewarded elect : John Friday (HBComm '81), with this wonderful accomplishment. Let it Treasurer: Mark Tilbury (HBComm '94), be known that we value your interest and and Member-at-large: Lynne Peters (BPE involvement with Lakehead University and '78, BEd '82, MEd '92). with our students o f the future. Please Board members continuing their terms of remember your alma mater as you move on office are Ben Kaminski (BA '82), David to the next challenge in your lives . Heald (BA '84) , and Mary Sacco (BA '87). Board Development Past-president Betty Coates (BScN '69) will be our representative to the Board of Governors for 1997-2000, replacing Joseph Baratta (BA '70, BEd '75, MEd '80) . A spe- Convocation '96 Thank You Sponsors and Donors to the 1996 Alumni Mixed Curling Bonspiel Ontario Hydro Pepsi-Cola Canada In his speech to the graduating class, honorary degree recipient Lorne Everett (HBSc'68) spoke about the early choices he made in becoming an expert on hazardous waste and groundwater monitoring. "Don't compromise your ethics," he advised. "Take the high road, and if there is ever a problem, you can walk away with your credibility intact. " Mary Anderson (BA '66, HBSW'82) assists Valerie Le/lava, the Dean of Arts & Science medal winner for the highest-ranking student in the Honours Bachelor of Social Work program. Honorary Degree Recipients Paul Harms, BA (Hons) Rachel Anne Harris, BSc/BEd Louis Dudek - Valerie Joanne Lellava, BA (Hons), BEd, Belinda Jean Schoeman, BSc (Hons) McM ,BEcl Poet, Author .md Teacher Lorne G. Evere11 - Perth's Dry Cleaners Lenore Untinen - Petals 'n Pots Robert Paterson - Bombardier Inc. Pizza Hut Melvin f Pervms - Bourkes Drug Store Print Pros Ronald R1sumak1 - Canada Safeway Chronicle Journal Coca Cola Bottling Dave Douglas Jewellers Elephant & Castle Ernst & Young Red Carpet Coffee Services Scott-Bathgate Ltd. Shell Rapid Lube The Brewing Experience 1 i Cheryl A. Bobyk, BNBEcl Women's Advocate Debra Sheree Tausenclrrcnde. BSW (Hons) Caroline Helen Roy, Dip! Nat Lang Inst Local Businessman Jeffrey Cecil Henry Donovan, BSc Donna Lee Johnson, BScF (Hons), BEd, MEd Engmeer and Entrepreneur Raewyn Marie Seaberg. BSc The Governor-General's Gold Medal Gordon Arthur Keeler, BSc (Hons) Joseph Lawrence Ladouceur, BScF (Hons), Businessman and Dean Braun's Medals MSc F Fellow of Lakehead University Janice L. Friday, BScN The Governor General's Silver Medal Mae Kmt - Kmryna Stephanie Haras, BOR (Hons) Ronald Peter Andrew Petrick, BSc (Hons) Alumni Honour Award Terri Lee Badiou. Dip\ Lib & Info Studies, BA The Governor-General's College Bronze Joseph Robert Logozzo Peter Hass, BAdmin, BComm (Hons) Medal Poulin Award Norman DJ. Meyers, BEng Lee Richard Hu11on, Dip Eng Tech Adam Molai, BCornm (Hons) Gerald William Hodgson, Dip Eng Tech The Lieutenant-Governors' Medal President's Awards Lee Richard Hu11on. Dip\ Eng Tech Jeffrey Cecil Henry Donovan, BSc Adele Ritchie, BA (Hons) Penny Lynn Ratushniak, Dip\ For The Chancellor's Medal Entrep1·cneur Royal Lepage Real Estate Speedy Muffler King Scientis1 BSW (Hons) Health Director Framing & Art Centre The Outpost Thrifty Car Rental David William Maijala, Dip\ Eng Tech, BEng Harley Young, BComm (Hons) Kristina S. Malek, BA, BFA (Hons) Gear Up For Outdoors Thunder Bay Hydro Adam Molai, BComm (Hons) Donna Nadine Thomas, BID UM, BScF (Hons) Adelia Mary Rooney, BA Julie Ann Nisbw, BNBEd Peter K. Waycik, BScF (Hons) The Dean of Arts and Science's Medals Aaron Laurence Skillen, HBK Samamha Kipper, BA Williiarn A. West Education Medals Deanna Leah Oye, BMusic (Hons) Kimberly Dawn Bolen. BNBEd Hoito Restaurant Humphrey Sanitation Supplies Kalax Computer Systems Inc. Thunder Bay Whiskey Jacks Versa Foods Video Village Spccicil tlwnhs lo the volwllcer C1lu11111i 111c1rslwls and the sponsors of th e Graci '96 Party in the Outpost: Tllllnclcr Bay T,·avcl Limited, Airlanc I-lolcl, and /11/crAcl lntcnwlional. Keg Restaurant Nor'Wester 11 �OF EVENTS contact grads directly by mail and by phone . To the "lost grads" whose current addresses are not available, they write, LU Web Site in volunteering for such a pro - "Dear Heather, Sonya, Nancy, The gram in your city, call the Alumni Services Office at (807) Noel, Pamela, Kathryn, Cindy, Anna , Laurene, Alison, Pat, 343-8155 or toll free at 1-800- Cathy, Angela, Lorraine, Marja, 832-8076. Kathy, Loretta, Pam, Wendy, Lakehead and the City of Lucky Winner Cheryl, Brenda and Debra. We'd Thunder Bay Congratulations Volunteers for Admissions and Recruitment winner of the draw for a free Internet address for Lakehead University is http:// wwwlakeheadu.ca. Check it out. You'll find information on The Alumni Services Office is working with the Admissions Office of Lakehead University to establish a joint Alumni Admissions Program. This pro- to Printables , time we will promptly send you information regarding location Thunder Bay Chamber of Commerce's "After Business " and times of getting together. If us a little note and we'll share it March. at the reunion." Pehkonen, RR #l , Marja Pehkonen and Noel Stout Kaministiquia, Ont. POT lXO are planning an informal or Noel (Presio) Stout, recruitment of new students for reunion in Thunder Bay on 122 Cottonwood Crescent, August 2-3, 1996, and plan to C ◊ Alumni of Lakehead University Exclusive Internet Offer Only $5,95 per mo(+$20 one-time startup fee: Free software optional) Services Include: • 18 cumulative hours of access per month (any overage charged at a rate of 1 cent per minute) Electronic mail, WWW ·surfing", newsgroups. • PPP connection Exclusive rates for members of the Alumni Association of Lakehead University, For details call Alumni Services at 343-8155 or E-mail rzuback@lakeheadu.ca. following organizations and businesses to provide services to its members: • Bank of Montreal MasterCard • Seaboard Life Group Life Insurance N Thunder Bay, Ont. P7A 3L9. Recently, it has been brought to our attention that certain individuals have been contacting For information about any of the events listed above, contact: Kristine Carey Lakehead grads, claiming to be Alumni Assistant doing so on behalf of the Office of Alumni Services Alumni Association, and then Lakehead University attempting 955 Oliver Road to sell products and services. Should you receive any Thunder Bay, Ontario solicitations you believe are Telephone: (807) 343-81 55 unauthorized, contact Rob Fax: (807) 343-8999 Zuback, Manager of Alumni E-mail: Services at (807) 343-8916. D rob.zuback@lakeheadu.ca • Campbell&:. Company Limited (Traders General) Group Home & Auto Insurance • Main River Clothing Alumni Clolhing Program Contact Marja (Kraft) the assistance of alumni in the GET proud of its contracts with the you can't make it, please send get-together at the Outpost last gram, if instituted, would enlist Lakehead. If you are interested The Alumni Association is love to hear from you at which ad in the Nor'Wester at the Class of '81 Nursing Reunion Be Aware Buying or Selling a Home? Raena Clara, B.A., B.Ed. • • • Residential Specialist MVA Designation Associate Broker • Dave Douglas Jewellers watches & rings The Outpost was the country's #1 University Pub for hosting live acts this year (1995-96). Catch the fever! We're the place to be to catch Canada's top touring acts. We offer reduced concert prices to Lakehead alumni for all our shows. Come and try our excellent food services currently enjoyed by thousands of students, alumni, staff and faculty all year long. We offer full table service for your pleasure. We also cater to any function to suit your needs and budget. • Financial Concept Group Inc. Group RRSP Thunder Bay's Concert Headquarters! Call 623-1331 Watch and Listen for Upcoming Events! Ste, #103, 1151 Barton St., Thunder Bay, ON, P7B SN3 Fax (807) 623-7956 343-8551 The Realtor Friends Recommend to Friends! f C a mp u s Annual Alumni Association Bocre Ball Tournament Friday, July 26, 1996 2:30 p.m. start time $15. 00 per person Alumni House (Avila Centre) Grounds includes delicious Beef-on-a-Kaiser roasted on the Versa open "pit" barbeque Call 343-8155 or fax 343-8999 Register Early- Limited Space!! Proceeds in support of LU. Residence Athletic Facilities and Alumni Services Sponsored by . , , , , , , , T e c h Lakehead University's Computer Store We carry: > IBM, Compaq, HP and CT-Touch Desktop Systems > IBM ThinkPads and Compaq Laptops > Educational Software > Games We also provide: > both Colour and B/W Laser Printing Located in the Braun Building Room 1070A Lakehead University 955 Oliver Rd Thunder Bay Ontario P7B 5E1 Service available in Th.under Bay only. 12 Nor'Wester Nor'Wester 13 �~ in July, 1995. David is working at the Manitoba legislature and Georgina practices law at the firm Aikins, MacAulay & Thorvaldson in Winnipeg. I :, · ' 'I s l i I \ I l ' 1980s 1960s John Schelling (BA'69) retired on December 13, 1995, as principal of St. Margaret Catholic School. 1970s Neil R. Campling (HBSc'73) is residing with his wife Linda in Darlington, England, where he works as North Yorkshire County Archaeologist. Donald Scarcello (Bus.Dip'74, BA'75) was one of 10 individuals this year to receive the Certified General Accountants (CGA) Association of Ontario's Distinguished Service Award. He is Assistant Director of Revenue Collection with Revenue Canada Taxation in Windsor and lives in London with his wife Lea (LeMarbe) and their daughters Karen, 19, and Katie, 15. Al Lagadin (BSc/BEd'75) is employed with the Municipal Gas Corporation of Aurora, Ont. and has recently been appointed to the position of Market Development and Sales for Northwestern Ontario. Janet Sillman (HBA'76) and husband Tom Walters recently saw the safe arrival of their fourth child, Alina Helen Sillman Walters. "Ali" was born on August 23, 1995. Heather Lauder (BAIBEd'81) is residing in Spencerville, Ont., and working for the Leeds and Granville County Board of Education as a part-time art teacher. She gave birth to twin boys, Kirk and Neil, in December, 1995. They are brothers to Kris and Kelly. Barry Gural (B/\.77, BEd'81 ) is religious education curriculum chairperson at St. Patrick's High School in Thunder Bay. He recently received the Bishop Reding Award as the Secondary School Outstanding Teacher for the Northwest Region. Former Coordinator of Counselling Services at LU, Irmo Marini (BA'82, HBA'84, MA'85), earned his PhD in Rehabilitation at Auburn University in Auburn, Alabama, winning two awards for outstanding academic achievement. He now has a tenure-track position at Arkansas State University as Assistant Professor in Counselor Education and Psychology. His wife Darlene is a freshman at ASU majoring in Communicative Disorders. He can be reached at P. 0. Box 2805, State University, AR 72467, U.S.A, telephone: (501) 931-5246. Richard Hicks (MA'78 ) is employed at General Motors in St. Catharines and would enjoy hearing from his old friends in the graduate program. He asks, "Does anyone know what became of Dr. French?" You can write to Richard at 32 Strada Blvd., St. Catharines, Ont., L2S 3L8 or phone (905) 685-7401. Valerie Bristowe RN (BA'78) is employed at Banker's Hall Health Complex as a Health Promotion Consultant teaching fitness classes and arthritis management, and training fitness specialty leaders. She is pursuing post-graduate nursing studies at Athabasca University in Alberta. Scott Tozer (Eng.Tech'82) married Lucille (nee Schaaf) in 1986. They have two children: Tanis, 6, and Graydon, 1. Since graduation, Scott has been working as a Project Manager David Chadwick (Lib.Tech'79, BA'81) is happy to announce that he and spouse Georgina Garrett had their third son Peter N M E M 0 R A Lakehead University extends condolences to the family and friends of the fallowing: Cop,Jackjames (B.A:66), October 11, 1995 Nick Joblin (HBComm'77) and his wife Jackie have moved from Edmonton to Vancouver where he is employed with Siemens Electric Ltd. 14 Nor'Wester M Godecki, Anthony Mark 'Tony' (B.A'.73), February 13, 1996 Menzies, Clifford Lendon (HBA'.71), February 14, 1996 Niemi, Cynthia Cherrell (Rainsforth), (BA'.74),January 5, 1996 Wilkins, Mary (BAdmin'78), December 17, 1995 specializing in geotechnical engineering for DST Consulting Engineers Inc., a Northwestern Ontario based international consulting firm. During the summer of 1995, Scott took on an assignment in their overseas office located in Beirut, Lebanon. Wendy Mauracher (HBPHE'82), her husband Rob and their three girls are now living in Kingston, Jamaica. Rob works for Air Jamaica and Wendy will be involved in activities at the American-Canadian International School which their children attend. David Tarjan (HBScF'84) is residing in Switzerland where he works as an evangelist for the Church of Christ and as a research assistant at the Swiss Federal Research Institute. He was married in 1990 to Kirsten Ulrich and they have two children: Jessica, born in 1992, and Timothy, born in 1994. Dee (nee Hurlston) (B/\.85) and Rob Bennett (HBSc'82, BEd'85) are residing in the Cayman Islands. Rob is self-employed as a landscaping consultant and is also working part-time on their Cayman Islands Botanic Park project. Dee teaches five-yearolds and is head of infants at a government school. Since graduation, Rudy E. Rawlins (BEng'86) worked for Schlumberger Industries in Toronto and College Station in Texas and was promoted to the position of Engineering Manager for Digital Fault Recorders. He is now a Design Engineer for Hardware Maintenance and Diagnostics at Northern Telecom in Toronto. Coleen Doerksen (nee Finlayson) (MA'86) is married and living in Morden, Man., on a 40-acre hobby farm. She works in two school divisions as a school psychologist. Since 1989, Pat (HBA'86, BEd'88) and John Lychek (LTI'57) have been living in Hanover, Ont., where Pat is employed by the Bruce-Grey Roman Catholic Separate School Board and John is retired. They will be relocating to Sydney, Australia, where Pat will be working as a teacher in 1996 as part of the Ontario Federation for Educational Exchange. Lori (nee Wilson) Vander Ploeg (HBScN'87) married firefighter, Robert, in 1991. They are the proud parents of two sons: Jacob, born in February, 1992, and William, born in August, 1993. Lori is working part-time at Thunder Bay Regional Hospital - McKellar Campus, on the Pediatrics Floor. David L. Nicol (HBSc'87, MSc'91) and his wife, Marilyn of Carrot River, Sask., were married on October 22, 1994. David works as a geological consultant in oil and gas exploration while Marilyn is an Executive Secretary with Ranger Oil Ltd. They reside on an acreage near Calgary with their dogs Tracker and Shasta. Gary K. T. Sim (BSc'87, HBSc'89, MSc'92) is working for Motorola in Penang, Malaysia, as a Surface Mount Technology Engineer making mobile telecommunication products (walkie-talkies). He has been surfing the Internet and says he is happy to see that Lakehead looks "forever young." He really enjoyed life at LU and sends regards to the Physics Department (especially Joan). Dr. Joseph P. McMullin (MA'87) graduated from McMaster University in 1994 with his MD degree. He is now living in Hamilton and enrolled in the Internal Medicine residency program at McMaster. Nina Morrow (nee Ariganello) (BA/BEd'89) and husband Michael are proud to announce the birth of their first child, Jonathan Michael. The newest "Montreal Canadiens' fan" was born December 15, 1996. Nina is employed by the Lakehead District Separate School Board as a French teacher. Patrick Matakala (HBScF'89, MSc'91) completed his PhD in Forestry at UBC in August, 1995. Since September, 1995, he has been employed as a Sessional Lecturer at UBC teaching four courses: Protected Areas Planning & Management; Recreation Resource Administration & Management; Recreation Resource Planning; and International Forestry. Lakehead University istance Education An Opportunity to Pursue Your University Studies at Home e Offer: A FLEXIBLE learning schedule INTERACTIVE multimedia courses DEGREE COURSES in a variety of disciplines START DATES (in September, January, February and May) rograms Offered: Master of Forestry Bachelor of Science - Nursing (post RN) Bachelor of Arts (General) Certificate in Bio/Health Sciences Certificate in Environmental Assessment ontact: Distance Education Lakehead University Thunder Bay, Ont. P7B SE 1 Tel. (807) 346-7730 Fax (807) 343-8008 e-mail: distance.education@lakeheadu.ca Harold Harkonen (BEng'89) married Tammy Gauvreau in September, 1993. Their daughter Kira was born December 4, 1994, and they were expecting their second child in June. Harold transferred from the Kimberly-Clark mill in Terrace Bay, Ont., to Coosa Pines, Alabama, in January, 1996, and they are making their home in Birmingham. He writes, "Any former classmates attending the IEEE Pulp and Paper Conference or the Olympics this summer are invited to look us up. Best wishes to the class of 19891" (continued on page 16) Find all the pieces to the puzzle ... ,~ I THUNDER BAY PUBLIC LIBRARY rl"\nnecting people ormation. ~i~f ~+¥, Nor'Wester 15 �1990s Armin E Cansino (BAdmin'90) married Chandra N isbet in 1995 and would like to thank Robert Bertolin (BAdmin'90) who represented Lakehead alumni at the wedding. He is self-employed at a fumiture and appliance store in Belize. He sends greetings to all his friends and encourages them to call him if they're ever in the country. Beth Potter ( nee Dougan) (BA'90) and her husband, Mike , welcomed the arrival of a baby brother for fou~yea~old Meghan at the end of January. Owen arri ved on the first anniversary of Beth's company, For Immediate Release Communications lnc., which specializes in media relations and promotion of special events and trade shows in the Greater Toronto Area. The family is living in Ajax, Ont. Kelly (nee Fettes) (BA'90) and David Litt (BAdmin'91) we re married in July, 1995. After graduation, Kelly went to Confederation College to study Travel & Tourism. She graduated on the Dean's List in 1994 and started work with Bayway Tours of Thunder Bay as Tour Assistant . She was promoted in 1995 to Tour Co-ordinator. In November, 1995, Bayway merged with Happy Time Tours , so she is now with Happy Time/Bayway Tours. David is Store Manager of Mark's Work Wearhouse. Lana (nee Bresel e ) (BEd'90 , MSc'90) and Rob Foster (HBSc '89) were married at Pukaskwa National Park in 1990. They lived in Tansania for g a Party? At lakehead University, we are able to accommodate and professionally serve your group of 15 to 600 people. Our Faculty Lounge will seat 50 to 130 people comfortably and The Little Dining Room is perfect for a formal dinner or dinner meeting of 10 to 15 people year 'round. Our Residence and Main Dining Halls are great for groups of up to 600 people. The Main Hall is available on Friday nights and weekends during the academic year while both are available any day of the week from May to August. Off-campus catering is available year 'round too. Let our expert chefs and catering staff tempt you with a wide range of menu items to suit your taste buds and your pocketbooks. two-and-a-half years while Rob worked on his D.Phil. in Zoology. Since completing his degree in 1993 they have been residing in Thunder Bay where Lana is teaching with the Lakehead Board of Education and Rob is a founding partner of Northern Bioscience, an ecological consulting firm . They are pleased to announce the birth of their baby "Dung Beetle," Megan Marie Bresele Foster, on February 14, 1996 . They can be reached by E-mail at : rfoster@norlin k. net. Thunder Bay Regional Hospital - McKellar Campus. Margaret Saxe (nee Macleod) (HBScN ' 91) was married in January, 1996, to Charles S. Saxe, Jr., an industrial engineer and graduate of Texas A&M Uni versity. She is living in Victoria, Texas, and will be travelling across the country with her husband's company. She is currently working in a cardiothoracic ICU and is pursuing a career in research and ethics. on maternity leave from the Frank (Francesco) Carpino ( HBPE'92, BEd'94) married Lori-Ann Newman (BA/BEd '93) in April , 1995 . He is employed as a Kinesiologist at the Thunder Bay Physiotherapy Centre and supply teaches for the Roman Catholic Separate School Board. Maternal/Newborn Service at (continued 011 page 18) Laura (nee Favot) (HBScN'91 ) and Terry Prodanyk (BSc'92, BEd '93 ) had their first child, Monica Laura, in November, 1995. Terry is working for North Star Electric and Laura is Lakehead University Student Opportunity Trust Fund Lakehead University has established the "Lakehead University Student Opportunity Trust Fund' in response GRADUATES ~z~g Don't just hang your diploma on the wall: turn it into a new car. The Ford Graduate Rebate Program Because you are, or are about to be, a graduate, you can get the Ford or Mercury car or truck you want and get $750 Cash Back. And that's over and above most other consumer retail offers from Ford of Canada advertised to the general public at the time of purchase. Your Dealer has complete details. . ~ ~ ~~.,t -.-◄ I_ - -- ..... . .. ·-· v ~ . ~ For each endowed dollar donated towards student financial aid at Lakehead University between May 7, 1996 and March 31, 1997 the Ontario Government will match this funding dollar for dollar. Please give your support to deserving -. Retirements T Sports Banquets T Fashion Shows -. Class Reunions T Anniversaries -. Weddings -. Birthdays For more information. call: Versa Campus Services Catering Office Tel (807) 343-8337 Fax (807) 343-8649 16 Nor'Wester students who need your assistance now. Find out how you can ger involved by calling Jo-Anne Silverman, Development Office, Lakehead University (807) 343-8910. LAKEHEAD iuNIVERSITY Helmut Eckhardt PEng (BEng'74) to the Ontario Government's new student funding program. Alumni Profile lnterdt,.-,,_ 1aqtlt@o1al FORD autocentre {807) 344-7235 700 TENTH AVENUE AT BALMORAL 1-800-465-3903 Out ofTown Customers By Kathy McGowan Helm Eckhardt has made a niche for himself in the construction industry. He is working as an lndustrial Technology Advisor with the Industrial Research Assistance Program (TRAP) of the National Research Council of Canada, and his services are provided through a contribution agreement between the Canadian Manufactured Housing Association and !RAP. lRAP assists small and medium -sized industries with competitive strategies in technology research and development to help them become more competitive and profitable. Eckhardt's mandate is to promote the acquisition, development and use of technology and to raise the technological awareness and capabilities of Canadian enterpiises. One success story involved six firms from across Canada who went to Germany recently to meet with mem be rs o [ the Ge rm an Building and Recycling lndu stry Associat io n. The se fir ms be came aware o f th e scope and magnitude of opportunities tha t are available in the co ns truc ti on m ate ri al recycling industries. Some of these businesses are now key players in la rge -scal e projec t d eco mmi ssio nin g and co ns truc ti on was te de molitio n management. The project had special meaning to Eckhardt, w~0, spent three years (1988-,«])l) in Germany as European., Branch Manager of a Canadian crown corporation, providing infras trucrure services to the Canadian Forces. Another recent success was the restructuring of a Cornwall insulation manufacturer, providing a more marketable product and assuring approximately 40 jobs. Given Eckhardt\:; expertise and diverse background in the technology sector, it is easy to understand why these projects prospered. Eckhardt met his w ife Christine in Calgary where he was a project cons ultant fo r the $20 7 mill10n twin-tower Petro Canada Cemre. He was also involved , ove r a 10-yea r period , in shaping the Calgary commercial skyline. Eckhardt , hi s wi fe and three chil d ren li ve in Ott awa, Onlario. He invites members of his graduating class to contact him . His E-mail address is helm .eckhardt@irap. nrc.ca. ~ Nor ' Wester 17 �(continued from page 16) and Science Medal for the highest graduating science marks. He is married to the former Amy Williamson. Glen Burns (HBComm'92) obtained his CA designation in December, 1995. He is a senior staff accountant at Ernst & Young in Thunder Bay Cynthia Scott (BAdmin'94) and Steven Heimbecker are to be married on August 10, 1996. She is a Network Support Analyst for CP Rail in Toronto. Cynthia thanks all of the professors who helped her see her real potential. She says she owes her career success to them and the business program at Lakehead. Colleen (nee Burr) (BA/BEd'95) and Kevin O'Dair (BAdmin'93) were married on July 8, 1995. They reside in Cornwall and Kevin commutes to his work with Nortel in Brockville. Colleen is looking for a full-time teaching position and has her hands full with Ellen, 3. They are expecting a baby in July. Paul McCausland (BAdmin'94) is working as an Auditing Technician with the accounting firm Humpage Taylor McDonald in Peterborough, Ont. He and his wife, Jennifer, were expecting the birth of their first child in the spring. One year after graduation, Michelle Guitard (HBA'93) started working with the Addiction Research Foundation and moved to the Kenora office a few months later. Her husband is Robert Ott (HBSW/BA'.95). Derek Serianni (BA'94) is working with Tri-Media in Welland, Ont., in charge of computer systems and Internet services. He owns a computer consulting business called Virtual Media and on weekends he works as a DJ. He and Andrea Gledhill are planning to get married in a couple of years. Geoff Hill (BSc'94) achieved a "first-time ever" accomplishment at The University of Western Ontario in London. He earned 100 percent in his second-year chemistry class where he is enrolled in a PhD (chemistry) program. During his four years at Lakehead, he earned 100 percent in five classes and graduated with first-class standing, receiving the Dean of Ar_ts ~a\ Mark Wilhelm (BAdmin'94) and Paula Petsche are getting married on August 17, 1996, and they have bought a house in • Waterdown. Mark works for Arrow Electronics Canada and was awarded "top sales rep" in a product category at the Arrow National Sales Conference in South Carolina. Richard Snyder (BEng'94) is residing in Courtenay, B.C. , and recently began a new job with the Levelton Association. Richard Darke (BEd'94) married Tania Toop on October 7, 1995. They bought a house in Dundas, Ont., where they live with their yellow lab "Mac" and cat "Tigger." Richard has joined Tania's father in the family business. Julia Wolst (nee Belleghem) (BA'.94, BEd'95) married Steven on August 12, 1995, after a year apart while she finished her education in Thunder Bay and he prepared for his Paramedic I training at Humber College in Toronto. A month after the wedding, she was hired to teach Grade 6- 7 at Uptergrove Public School in Orillia. She met Len Dunkley (BA'94, BEd'95) at a Simcoe County Conference for new teachers, and wonders who else from her grad class is employed? Anyone interested in sharing stories can write to her at Uptergrove Public School, RR #7, Orillia, Ont., UV 6H7. • p,.<'~ • A 5SOCtatzon Qh ~~ .1111,1'\,t P~e7Z ' ~~,, .. ~ All Alumni, Students, Staff, Faculty and Friends Welcome Friday, August 1 6, 1996 2:00 p.m. shotgun start Centennial Golf Course $40 per golfer, $160 per team • includes a limited edition Alumni T-shirt Barbeque Steak Dinner at Alumni Ho"use /Avila Centre) Cafeteria To register, please call Alumni Services at 343-8155 or Fax 343-8999 All proceeds in support of Alumni Association Scholarships. Bursaries and Programs. Sponsored by Financial f -C:-on~roup- T 18 Nor'Wester J. Karen Reynolds (MEd'94) is living in Vancouver and writing her dissertation entitled, "A Case Study of the Practice of Assessment in One Intermediate Elementary School Classroom." She has held a SSHRC Fellowship for the past three years and received the Faculty of Education Graduate Student Award for Research in British Columbia. Maxine Brown (BA/BEd '94) started a new job as a math teacher at Canterbury High School in Ottawa. Her partner Jonathan Hare (HBA'.94) is currently attending an Education program at the University of Western Sydney in Australia. Solomon (BA/BEd'95) and Debbie Kakagamic (BA'95) are pleased to announce the birth of their son Solomon WindWalker Kakagamic on November 1, 1995. He is a brother (finally) for sisters, Candi, Melanie, Amy, Rebecca, Cheyenne and Shoshonee! Solomon works at Pelican Falls First Nations High School. In March, Debbie was elected Band Councillor of Lake Nipigon Ojibway First Nation. 0 Adam Molai Consulting Service. (continued from page 1) Oh, and the business he plans to start in Zimbabwe? He and fellow LU graduate John Rajala (HBComm'96) are going to market electrical equipment used in the production of solar and wind energy in Zimbabwe, South Africa and Mozambique. Their prototype, featured on the cover, is currently being manufactured in Northwestern Ontario but their long-range plan is to move production to Zimbabwe. Now thats technology transfer! 0 In the final round of competition, the top five student teams in Canada are chosen to compete in the categories of marketing, finance, labour relations, management information systems, and debating. Molai, who is reported to have developed into a "star debater," praises Lakehead University saying, "Compared to the ICBC competitors from other universities, I could see that my education at Lakehead University has been superior." As a parting gift to the University, Adam Molai established an endowment that will see an annual award of $500 go to a third-year or fourth-year business student who has been involved with the students' club (LUBA), the Queen's Intercollegiate Business Competition (ICBC), or the LU Management At Convocation in May, Adam Molai received two awards: the Poulin Award for outstanding citizenship and for contributing most to the welfare of the University, and the President's Award for students who, by their activities and achievements, have earned the gratitude of the University President's Perspective be officially launching our Lakehead University Student Opportunity Trust Fund as a Share Our Northern Vision project, and I would encourage all of you to give this initiative special consideration this next year. As well, please direct us to your corporate and business offices if you feel a call would be appropriate. The Student Opportunity Trust Fund would also make an excellent project for service clubs. (continued from page 7) fund. In Lakehead University 's case, it will be called "The Lakehead University Student Opportunity Trust Fund. " For each dollar donated to this Fund between May 7, 1996 and March 31, 1997, the Ontario government will match the funding dollar for dollar. This is a great opportunity for us to seek out an endowed base of student aid for our future students, since your financial support will be matched 100 percent. Within the Fund, awards can still be named and designated and very few restrictions will apply other than the donated and matched money must be endowed, and only interest and investment income will be used to support awards. Within the next few weeks, Lakehead University will I am excited about this new opportunity. By working with you, the alumni, together we can move "Back to the Future." 0 For further information about the Lakehead University Student Opportunity Trust Fund, contact Jo-Anne Silverman (807) 343-8910. Surf 1Nith Thunder'Bay Travel on the Internet! Check us out at TBTravel@Lakeheadu.ca Come and see our home page with Travel Universe. ■ Service,? Travel 5 • Representative Thunder Bay Travel Limited Open 6 Days a Week • Toll Free 1-800-465-3939 • 202 Red River Road 345-2535 • 122 Centennial Square 623-7473 • Marathon Centre Mall 229· 2500 Internet Address: tbtravel@lakeheadu.ca p,enen~ KnijWS NO!BOU~ds. An international presence. Innovative technology. Outstanding reliability. Exceptional performance. As world-leading designers and manufacturers of passenger rail vehicles, our experience knows no bounds. il Bombardier Inc. Transportation Equipment Group Thunder Bay, Ontario Nor'Wester 19 �J ~hunder Say -YTELEPHONE Alumni Update & Change of Address are at home at CONNE Thunder Bay Telephone: Voluntary Subscription Appeal Name: Address: Yes, I want to be a Voluntary Subscriber. I enclose my cheque for Lakehead. The reason they joined us? Opportunity. Postal Code: Tele_ehone: Degree(s): Year(s) of Graduation: NNECTION~ Employer's Name: Address: Postal Code: Each year we send out more than 51,000 copies of the Nor'Wester to alumni and friends. It's our way of keeping in touch and keeping you informed. Yet printing and mailing costs continue to increase. That is why we are asking you to consider becoming a Voluntary Su~scriber. By giving us your support, you can help to ensure the Nor'Wester will continue to maintain its quality and frequency of publication. In fact, more than 10% of our staff attended Tele_ehone: Connections Position: Spouse/Partner's Name: University/College: Occu])_ation: If your name has changed or is incorrect and you would like the records at Lakehead amended, please complete this section: Name on Record: Name Should be: Signature: 0$20 Have you Married? Started a New Job? Begun a Family? Received an Award? If so, we want 0$30 to hear from you . Take a moment to tell us what is new and exciting in your life . (Use a separate page if necessary.) 0 Other graduates helped us design and build our Make cheques payable to "Lakehead University - Nor'Wester" and mail to: recently completed, 100% digitally switched, The Alumni Association Lakehead University 955 Oliver Rd Thunder Bay, Ont. P7B 5El Telephone (80 7) 34 3-815 5 or toll-free (in Canada) at 1-800-832-8076 to make your gift by Visa or MasterCard. 20 N o r' We st e r high speed fibre optic exchange system. We're pleased to have Lakehead University Clip and send to Alumni Services, Lakehead University, Thunder Bay, Ont. P7B 5El Telephone: (807) 343-8155, Fax: (807) 343-8999, E-mail: frances.harding@lakeheadu .ca graduates on our team of 250 local residentskeeping our city connected to the world. 1r � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Lakehead University Alumni Collection Description An account of the resource Material kept by the Lakehead University Alumni Association, or donated by Alumni to the Association. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Nor'Wester Magazine, Summer 1996, Vol. 13 No. 2 Subject The topic of the resource Universities Description An account of the resource This issue of Nor'Wester includes a profile of Adam Molai, and a discussion of challenges caused by government cutbacks to university funding. Creator An entity primarily responsible for making the resource Lakehead University Date A point or period of time associated with an event in the lifecycle of the resource 1996 Format The file format, physical medium, or dimensions of the resource PDF Language A language of the resource English Type The nature or genre of the resource Text https://digitalcollections.lakeheadu.ca/files/original/72cc0c183e5d4fc8ab0811c66edf140d.pdf 7527b93a85865027caf582e7cb0434fb PDF Text Text 72nd Annual Meeting Thunder Bay, Ontario - May 21-22, 2026 Institute on Lake Superior Geology Part 1 – Program and Abstracts �Thank you to our sponsors! �65th Annual Meeting Institute on Lake Superior Geology May 21-22, 2026 Thunder Bay, Ontario HOSTED BY: Mark Puumala and Peter Hinz Co-Chairs Ontario Geological Survey (Retired) Proceedings - Volume 72 Part 1 – Program and Abstracts Compiled and edited by Pete Hollings & Mark Smyk Cover Photos: Top: Amethyst veins in Rossport Formation at the Blue Points Amethyst Mine, north of Highway 11-17 near Big Pearl Lake.Middle: Neoarchean mafic metavolcanic rocks, Highway 102 at the intersection with Mud Lake Road. Bottom: Corestones of the McKenzie Granite at the Archean-Paleoproterozic unconformity, Highway 11-17 near Crystal Beach. All photos courtesy Mark Puumala. �72nd Institute on Lake Superior Geology Volume 72 consists of: Part 1: Program and Abstracts Part 2: Field Trip Guidebook Trips 1 & 4: “Classic” Geological Sites in the Thunder Bay Area Trip 2: Geology of the Quetico Supprovince North of Thunder Bay Trip 3: Gold Deposits of the Shebandowan Greenstone Belt Trip 5: Structural Geology and Gold Mineralisation of the Mine Centre Area Trip 6: Amethyst Deposits of Thunder Bay Reference to material in Part 1 should follow the example below: Akin, K. and Swanson-Hysell, N., 2026. Constraining the 3-D Geometry of the Duluth Complex, MN, Using Magnetic Fabrics and Paleomagnetic Data. In; Hollings, P. and Smyk,, M., (Eds.), Institute on Lake Superior Geology Proceedings, 72nd Annual Meeting, Thunder Bay, Ontario, Part 1 - Abstracts and Proceedings. v.71, part 1, 1-2. Published by the 72nd Institute on Lake Superior Geology and distributed by the ILSG Secretary: Pete Hollings - ILSG Secretary Department of Geology Lakehead University 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada Email: peter.hollings@lakeheadu.ca ILSG website: www.lakesuperiorgeology.org ISSN 1042-9964 �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Table of Contents Institutes on Lake Superior Geology, 1955-2026............................................................... ii Sam Goldich and the Goldich Medal................................................................................. iv Goldich Medal Guidelines................................................................................................. iv Institute on Lake Superior Geology Goldich Medal............................................................v Goldich Medalists.............................................................................................................. vi Sam Goldich and the Goldich Medal................................................................................ vii Goldich Medal Guidelines............................................................................................... viii Goldich Medal Committee ................................................................................................ ix 2026 Goldich Medal Recipient.......................................................................................... ix Citation for Goldich Medal Recipient..................................................................................x Honoring the Pioneers of Lake Superior Geology............................................................. xi In Memoria........................................................................................................................ xii Report of the Chair of the 71st Annual Meeting .............................................................. xvi Eisenbrey Student Travel Awards.................................................................................... xix Joe Mancuso Student Research Awards.............................................................................xx Doug Duskin Student Paper Awards..................................................................................xx 2026 Student Paper Awards Committee........................................................................... xxi Board of Directors............................................................................................................ xxi Local Committee.............................................................................................................. xxi Field Trip Leaders and Guidebook Authors.................................................................... xxii Index..................................................................................................................................88 -i- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Institutes on Lake Superior Geology, 1955-2026 # Date Place Chairs 1 1955 Minneapolis, Minnesota C.E. Dutton 2 1956 Houghton, Michigan A.K. Snelgrove 3 1957 East Lansing, Michigan B.T. Sandefur 4 1958 Duluth, Minnesota R.W. Marsden 5 1959 Minneapolis, Minnesota G.M. Schwartz & C. Craddock 6 1960 Madison, Wisconsin E.N. Cameron 7 1961 Port Arthur, Ontario E.G. Pye 8 1962 Houghton, Michigan A.K. Snelgrove 9 1963 Duluth, Minnesota H. Lepp 10 1964 Ishpeming, Michigan A.T. Broderick 11 1965 St. Paul, Minnesota P.K. Sims & R.K. Hogberg 12 1966 Sault Ste. Marie, Michigan R.W. White 13 1967 East Lansing, Michigan W.J. Hinze 14 1968 Superior, Wisconsin A.B. Dickas 15 1969 Oshkosh, Wisconsin G.L. LaBerge 16 1970 Thunder Bay, Ontario M.W. Bartley & E. Mercy 17 1971 Duluth, Minnesota D.M. Davidson 18 1972 Houghton, Michigan J. Kalliokoski - ii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 19 1973 Madison, Wisconsin M.E. Ostrom 20 1974 Sault Ste. Marie, Ontario P.E. Giblin 21 1975 Marquette, Michigan J.D. Hughes 22 1976 St. Paul, Minnesota M. Walton 23 1977 Thunder Bay, Ontario M.M. Kehlenbeck 24 1978 Milwaukee, Wisconsin G. Mursky 25 1979 Duluth, Minnesota D.M. Davidson 26 1980 Eau Claire, Wisconsin P.E. Myers 27 1981 East Lansing, Michigan W.C. Cambray 28 1982 International Falls, Minnesota D.L. Southwick 29 1983 Houghton, Michigan T.J. Bornhorst 30 1984 Wausau, Wisconsin G.L. LaBerge 31 1985 Kenora, Ontario C.E. Blackburn 32 1986 Wisconsin Rapids, Wisconsin J.K. Greenberg 33 1987 Wawa, Ontario E.D. Frey & R.P. Sage 34 1988 Marquette, Michigan J. S. Klasner 35 1989 Duluth, Minnesota J.C. Green 36 1990 Thunder Bay, Ontario M.M. Kehlenbeck 37 1991 Eau Claire, Wisconsin P.E. Myers 38 1992 Hurley, Wisconsin A.B. Dickas 39 1993 Eveleth, Minnesota D.L. Southwick 40 1994 Houghton, Michigan T.J. Bornhorst 41 1995 Marathon, Ontario M.C. Smyk 42 1996 Cable, Wisconsin L.G. Woodruff 43 1997 Sudbury, Ontario R.P. Sage & W. Meyer 44 1998 Minneapolis, Minnesota J.D. Miller & M.A. Jirsa 45 1999 Marquette, Michigan T.J. Bornhorst & R.S. Regis 46 2000 Thunder Bay, Ontario S.A. Kissin & P. Fralick 47 2001 Madison, Wisconsin M.G. Mudrey & Jr., B.A. Brown 48 2002 Kenora, Ontario P. Hinz & R.C. Beard 49 2003 Iron Mountain, Michigan L. Woodruff & W.F. Cannon 50 2004 Duluth, Minnesota S. Hauck & M. Severson 51 2005 Nipigon, Ontario M. Smyk & P. Hollings 52 2006 Sault Ste. Marie, Ontario A. Wilson & R.Sage 53 2007 Lutsen, Minnesota L. Woodruff & J. Miller 54 2008 Marquette, Michigan T. Bornhorst & J. Klasner - iii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 55 2009 Ely, Minnesota J. Miller, G. Hudak & D. Peterson 56 2010 International Falls, Minnesota M. Jirsa, P. Hollings, T. Boerboom, P. Hinz & M. Smyk 57 2011 Ashland, Wisconsin T. Fitz 58 2012 Thunder Bay, Ontario P. Hollings 59 2013 Houghton, Michigan T.J. Bornhorst & A. Blaske 60 2014 Hibbing, Minnesota J. Miller & M. Jirsa 61 2015 Dryden, Ontario R. Cundari & P. Hinz 62 2016 Duluth, Minnesota J. Miller, C. Schardt & D. Peterson 63 2017 Wawa, Ontario A. Pace, A. Wilson & T.J. Bornhorst 64 2018 Iron Mountain, Michigan L. Woodruff, W. Cannon & E.K. Stewart 65 2019 Terrace Bay, Ontario P. Hollings & M.C. Smyk 66 2020 Meeting cancelled Cancelled by the COVID-19 pandemic 67 2021 Virtual meeting M. Jirsa, M. Smyk & P. Hollings 68 2022 Sudbury, Ontario R.M. Easton & W. Bleeker 69 2023 Eau Claire, Wisconsin R. Lodge, E.K. Stewart, & C. Ames 70 2024 Houghton, Michigan T.J. Bornhorst, E. Vye, P. Cobin, & J. Degraff 71 2025 Mountain Iron, Minnesota A. Radakovich, A. Severson, E. Nowariak, S. Saari, A.C. Hirsch 72 2026 Thunder Bay, Ontario P. Hinz and M. Puumala - iv - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Institute on Lake Superior Geology Goldich Medal -v- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Goldich Medalists 1979 Samuel S. Goldich 1996 David L. Southwick 2012 James D. Miller 1980 not awarded 1997 Ronald P. Sage 2013 Tom Waggoner 1981 Carl E. Dutton, Jr 1998 Zell Peterman 2014 Laurel Woodruff 1982 Ralph W. Marsden 1999 Tsu-Ming Han 2015 Rodney J. Ikola 1983 Burton Boyum 2000 John C. Green 2016 Mark A. Jirsa 1984 Richard W. Ojakangas 2001 John S. Klasner 2017 Philip Fralick 1985 Paul K. Sims 2002 Ernest K. Lehmann 2018 Val W. Chandler 1986 G.B. Morey 2003 Klaus J. Schulz 2019 Mark Severson 1987 Henry H. Halls 2004 Paul Weiblen 2020 not awarded 1988 Walter S. White 2005 Mark Smyk 2021 Allan MacTavish 1989 Jorma Kalliokoski 2006 Michael G. Mudrey 2022 Terrence J. Boerboom 1990 Kenneth C. Card 2007 Joseph Mancuso 2023 Peter Hollings 1991 William Hinze 2008 Theodore J. Bornhorst 2024 Suzanne W. Nicholson 1992 William F. Cannon 2009 L. Gordon Medaris, Jr 2025 Robert Michael Easton 1993 Donald W. Davis 2010 William D. Addison & 2026 William (Bill) Rose 1994 Cedric Iverson 1995 Gene La Berge Gregory R. Brumpton 2011 Dean M. Rossell - vi - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Sam Goldich and the Goldich Medal Sam Goldich received an A.B. from the University of Minnesota in 1929, a M.A. from Syracuse University in 1930, and a Ph.D. from the University of Minnesota in 1936. During World War II Sam worked for the U.S. Geological Survey in mineral exploration. In 1948, Sam returned to the University of Minnesota, and became Professor and Director of the Rock Analysis Laboratory the following year. He rejoined the U.S. Geological Survey in 1959 and was appointed as the first Branch Chief of the Branch of Isotope Geology. Sam returned to academia in 1964 when he went to Pennsylvania State University. He left PSU in 1965 and moved to the State University of New York at Stony Brook, where he stayed for 3 years. Restless yet again, he moved to Northern Illinois University in 1968 where he was a professor until his retirement in 1977. Sam’s final move was to Denver where he became an emeritus at the Colorado School of Mines. Sam died in 2000, less than a month before his 92nd birthday. In the late 1970’s, Geological Society of America Special Paper 182, which included seminal geochronological studies by Sam Goldich and coworkers on the Archean rocks of the Minnesota River Valley, was nearing completion. At this time various ILSG regulars began discussing the possibility of recognizing Sam for his pioneering work on the resolution of age relationships and thus the geology of Precambrian rocks in the Lake Superior region. Three members, R.W. Ojakangas, J.O. Kalliokoski and G.B. Morey, presented the idea to the ILSG Board of Directors in 1978. The Board approved the creation of an award, provided funding could be obtained. It was suggested that collecting one or two dollars at registration for a dedicated account would provide resources for striking the medal. A general request was made to the ILSG membership for donations and Sam himself offered a challenge grant to match the contributions. In total $4,000 was collected and thus began the work of creating the Goldich Medal. The initial Goldich Award was presented to Sam by G.B. Morey in 1979 and consisted of a large paper proclamation. For the actual medal, G.B. Morey consulted with the foundry on production details, while Dick Ojakangas and Jorma Kalliokoski worked on the design of the award, suggesting that it be given for “outstanding contributions to the geology of the Lake Superior region.” Simultaneously, a committee of J.O. Kalliokosi, W.F. Cannon, M.M Kehlenbeck, G.B. Morey, and G. Mursky developed the Award Guidelines that were approved by the ILSG Board. By 1981 all the elements of the Goldich Award had come together, and the second recipient, Carl E. Dutton, Jr., received the Goldich Medal for 50 years of significant contributions to the understanding of the geology of the Lake Superior region. Since the beginning, the Awards Committee has consisted of individuals representing industry, government and academia, with each member of the Committee serving for three years. The medal is now awarded every year at the annual ILSG meeting. Reference: Morey, G.B. and Hanson, G.N. (editors). 1980. Selected studies of Archean gneisses and Lower Proterozoic rocks, southern Canadian Shield. Geological Society of America, Special Paper 182, 175 p. Prepared by various Goldich Medal Awardees, 2007 - vii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Goldich Medal Guidelines (Adopted by the Board of Directors, 1981; amended 1999) Preamble The Institute on Lake Superior Geology was born in 1955, as documented by the fact that the 27th annual meeting was held in 1981. The Institute’s continuing objectives are to deal with those aspects of geology that are related geographically to Lake Superior; to encourage the discussion of subjects and sponsoring field trips that will bring together geologists from academia, government surveys, and industry; and to maintain an informal but highly effective mode of operation. During the course of its existence, the membership of the Institute (that is, those geologists who indicate an interest in the objectives of the ILSG by attending) has become aware of the fact that certain of their colleagues have made particularly noteworthy and meritorious contributions to the understanding of Lake Superior geology and mineral deposits. The first award was made by ILSG to Sam Goldich in 1979 for his many contributions to the geology of the region extending over about 50 years. Subsequent medallists and this year’s recipient are listed in the table below. Award Guidelines 1) The medal shall be awarded annually by the ILSG Board of Directors to a geologist whose name is associated with a substantial interest in, and contribution to, the geology of the Lake Superior region. 2) The Board of Directors shall appoint the Goldich Medal Committee. The initial appointment will be of three members, one to serve for three years, one for two years, and one for one year. The member with the briefest incumbency shall be chair of the Nominating Committee. After the first year, the Board of Directors shall appoint at each spring meeting one new member who will serve for three years. In his/her third year this member shall be the chair. The Committee membership should reflect the main fields of interest and geographic distribution of ILSG membership. The out-going, senior member of the Board of Directors shall act as liaison between the Board and the Committee for a period of one year. 3) By the end of November, the Goldich Medal Committee shall make its recommendation to the Chair of the Board of Directors, who will then inform the Board of the nominee. 4) The Board of Directors normally will accept the nominee of the Committee, inform the medallist, and have one medal engraved appropriately for presentation at the next meeting of the Institute. 5) It is recommended that the Institute set aside annually from whatever sources, such funds as will be required to support the continuing costs of this award. Nominating Procedures 1) The deadline for nominations is November 1. Nominations shall be taken at any time by the Goldich Medal Committee. Committee members may themselves nominate candidates; however, Board members may not solicit for or support individual nominees. 2) Nominations must be in writing and supported by appropriate documentation such as letters of recommendation, lists of publications, curriculum vita’s, and evidence of contributions to Lake Superior geology and to the Institute. 3) Nominations are not restricted to Institute attendees, but are open to anyone who has worked on and contributed to the understanding of Lake Superior geology. - viii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Selection Guidelines 1) Nominees are to be evaluated on the basis of their contributions to Lake Superior geology (sensu lato) including: a) importance of relevant publications; b) promotion of discovery and utilization of natural resources; c) contributions to understanding of the natural history and environment of the region; d) generation of new ideas and concepts; and e) contributions to the training and education of geoscientists and the public. 2) Nominees are to be evaluated on their contributions to the Institute as demonstrated by attendance at Institute meetings, presentation of talks and posters, and service on Institute boards, committees, and field trips. 3) The relative weights given to each of the foregoing criteria must remain flexible and at the discretion of the Committee members. 4) There are several points to be considered by the Goldich Medal Committee: a) An attempt should be made to maintain a balance of medal recipients from each of the three estates— industry, academia, and government. b) It must be noted that industry geoscientists are at a disadvantage in that much of their work in not published. 5) Lake Superior has two sides, one the U.S., and the other Canada. This is undoubtedly one of the Institute’s great strengths and should be nurtured by equitable recognition of excellence in both countries. Goldich Medal Committee Serving through the meeting year shown in parentheses Marcia Bjornerud, Academic member - Chair (2023-2026) Robert Cundari, Government member (2024-2027) Phil Larson, Industry member (2025-2028) 2026 Goldich Medal Recipient William (Bill) I. Rose Michigan Tech University, Houghton, Michigan - ix - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Citation for Goldich Medal Recipient William I. Rose It is my heartfelt honor to present the late William I. Rose (Bill) with the 2026 Institute on Lake Superior Geology’s Goldich Medal. Bill has made tremendous contributions to the field of geoheritage and to increasing public understanding of the value and global importance of Lake Superior geology. This highly significant phase of his career, despite being retired for most of it, came from a genuine desire to encourage people to “get outside and love it”, to increase their Earth science literacy, and to deepen their love of Lake Superior. This work is strongly aligned with the criteria and spirit of this distinguished award. Bill served for 41 years as a professor of geology and volcanology at Michigan Technological University, working alongside scientists from around the world. He mentored countless graduate students, many of whom became close friends and respected colleagues. He took immense pride in their accomplishments and in his role advancing global volcano research. The volcanology program he helped build at Michigan Tech has become one of the world’s leading departments, drawing students from around the globe and producing leaders in the field. In his transition to retirement, Bill’s research focus shifted to geoscience education and outreach. This new direction was rooted in his dedication to K-12 educators through projects like the Michigan Teachers Excellence Program (MiTEP) and other teacher professional development in the Keweenaw that focused on Lake Superior geology. Bill held teachers in very high esteem, recognizing them as multipliers and the heart of essential knowledge growth. Working with educators helped launch Bill’s commitment to the field of geoheritage, inspiring the multitude of initiatives and learning resources that he developed for both formal and informal learners within the Keweenaw and Lake Superior regions. The thoughtful design of these programs yielded a vast inventory of Keweenaw geosites that could be used to explore the ways Lake Superior geology guides and influences our lives and culture. Bill shared countless “geostories” with the Keweenaw community - an expression he coined, along with “geopoetry”. His enthusiasm and energy never waned, and he never told a story the same way twice. His stories have made the global significance of Lake Superior geology accessible to people and have helped them to see how geology has shaped their own identity, history, and culture - the very essence of geoheritage. These stories resonated with people, inspiring a sense of pride rooted in the geology of our place and understanding just how fascinating Lake Superior geology is. His stories have inspired others to share their own geostories in the Keweenaw community, such as the Keweenaw National Historical Park and the Carnegie Museum. Bill shared every geoheritage outreach resource he created for zero profit in order to help the Keweenaw thrive and to promote greater understanding of Lake Superior geology. Signage, books, geotours, boulder gardens, museum exhibits, concerts in the belly of an abandoned copper mine, geologic contributions to federal grant applications to support local conservation efforts, and the labyrinth Keweenaw Geoheritage website - all of these were given freely to support our community shift from an extractive economic past and to be forward-thinking and supportive of conservation, education, recreation tourism opportunities - all rooted in our rich geology. This generosity is punctuated by the family gift of Silver Island to the Keweenaw Land Trust - an example of Bill’s strong advocacy for the protection of Lake Superior geosites and the promise of continued public access and education. -x- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 At the very heart of Bill’s education and outreach work is community. Through this work he fostered relationships at the local, national, and global level. At the local level his efforts have united teachers, artists, scientists, outdoor recreation enthusiasts, conservation organizations, and tourists, all drawn together by a common curiosity of Lake Superior geology. Nationally, Bill played a vital and formative role in shaping the vision for geoheritage in the United States, contributing to numerous workshops hosted by the U.S. Committee for Geoheritage and Geoparks and the Geological Society of America. At the global level, the Keweenaw has achieved recognition as a leader in the US geoheritage movement through Bill’s pursuit of prestigious global designations. He spearheaded the designation of the Jacobsville Sandstone as one of the first Global Heritage Stone Resources in the world and the first in the United States, recognized by the International Union of Geological Sciences (IUGS) and the UNESCO’s International Geoscience Program. Bill also promoted the Keweenaw as a strong candidate to become the first UNESCO Global Geopark in the United States. Within both global and national communities, the Keweenaw is largely viewed as a Geopark. Bill’s active membership with the ILSG served as a bridge between the professional geoscience community and the broader public. He was a first or co-author on numerous abstracts and field guides presented at ILSG meetings, including the Geological Field Trip, Eastern Isle Royale, Michigan (2013) and the Self-guided geological field trip to the Keweenaw Peninsula, Michigan (1994). Bill was visionary and big thinking; this is clearly reflected in his research and many contributions to the training and education of both geoscientists and the broader public. Bill’s leadership in geoheritage and passion for education and outreach has deepened public understanding, appreciation, and desire to protect Lake Superior geology. I am brimming with gratitude to see Bill’s service honored with the prestigious Goldich Medal award. Submitted by Erika Vye Great Lakes Research Center, MTU Honoring the Pioneers of Lake Superior Geology (Adopted by the Board of Directors, 2016) Preamble At the suggestion of Gene LaBerge, the 2016 executive board agreed to implement a program to recognize historic pioneers in the understanding of geology in the Lake Superior region. Beginning with the 2017 annual meeting, nominations will be accepted from the membership for geologists whose work was conducted primarily before the inception of the Institute in 1955. Biographical sketches of those pioneers will be presented at future annual meetings so that all may appreciate the value of their contributions. Selection of nominees will be decided in part by the organizing committee of each year’s annual meeting, in consultation with the Board, to ensure equitable geographic representation in the selection process. Award Guidelines 1) Nominations from the membership will be submitted via the Institute web site and forwarded to the Chair of the next Annual Meeting. The nominations will be no more than half a page in length and will summarize the contribution of the nominee. 2) The Organizing Committee will select one or two individuals to be highlighted at the next Annual meeting and submit those names to the Board for approval. - xi - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 3) The nominator will be requested to prepare a brief presentation to be given during the next annual meeting with a summary to be included in the Proceedings volume. 4) Unsuccessful nominations will be kept by the Secretary for two years and forwarded to the next meeting Chair; these nominations may be resubmitted at a later date. The Board will review this award every five years. Pioneers of Lake Superior Geology 2017 Douglass Houghton (1809-1845) 2018-20 not presented 2021 Newton Horace Winchell (1839-1914) 2022 Thomas Leslie Tanton (1890-1971) 2023 Thomas Benton Brooks (1836-1900) 2024 Roland Duer Irving (1847-1888) 2025 Robert Bell (1841-1917) In Memoria William Ingersoll Rose (1944-2025) William Ingersoll Rose, aged 81, died at his home in Eagle Harbor, Michigan, on July 17, 2025. Born in Detroit, Bill moved with his family at age five to New Mexico, where his love of rocks and the Earth began. Bill spent his childhood exploring the desert, riding horses, swimming in the neighborhood pool, and working at a local television station. New Mexico planted the seeds of a lifelong fascination with geology. After high school, Bill attended Dartmouth College, where he received Bachelor’s and Ph.D. degrees. Professor Dick Stoiber, one of the pioneers of volcano research, recognized potential in the unpolished young man and offered him an opportunity to study volcanoes in Guatemala—a pivotal experience that would shape Bill’s life. Bill and his wife, Nanno, settled in Houghton in 1970 where Bill joined the faculty of Michigan Tech. Bill’s work as a volcanologist took him across the globe and occasionally, Nanno and his two sons were able to come along. Following that first trip to Guatemala, Bill developed a deep passion for understanding volcanic eruptions. His adventures throughout Central America, along with his love of its people and landscapes, led him to speak Spanish and immerse himself in local cultures. He devoted himself to forecasting volcanic eruptions to help protect people living near volcanoes. Bill served for 41 years as a Professor of geology and volcanology at Michigan Tech, working alongside scientists from around the world. He mentored countless graduate students, many of whom became close friends and respected colleagues. He took immense pride in their accomplishments and in his role advancing global volcano research. The volcanology program he helped build at MTU has become one of the world’s leading departments, drawing students from around the globe and producing leaders in the field. He was instrumental in establishing signature programs such as the International Masters in Volcanology and Geotechniques and the Peace Corps Master’s International program in Mitigation of Geologic Natural Hazards. In retirement, Bill remained active and engaged. He developed geoheritage materials, led tours of Isle Royale and the Keweenaw Peninsula, and supported teachers, artists, kayakers, hikers, bicyclists, and tourists in learning - xii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 about the region’s rich geological and cultural history. The Keweenaw has achieved recognition as a leader in the US geoheritage movement through Bill’s pursuit of prestigious global designations. He spearheaded the designation of the Jacobsville Sandstone as one of the first Global Heritage Stone Resources in the world and the first in the United States, recognized by the International Union of Geological Sciences and the UNESCO’s International Geoscience Programme. Bill also promoted the Keweenaw to become the first UNESCO Global Geopark in the United States. Due to his efforts, within both global and national communities, the Keweenaw is viewed as a Geopark by definition. Many of these geoheritage initiatives were presented at ILSG. His Field Trip Guidebook for Isle Royale: Keweenawan Rift Geology, co-authored with Justin Olson, is one of ILSG’s Special Publications. For his remarkable work in the Lake Superior region, his teaching, supervisory and outreach efforts, and support of ILSG, Bill was posthumously awarded the Samuel S. Goldich Medal in 2026. Bill treasured time with his children and grandchildren, especially during family vacations in Eagle Harbor. Always curious, he took the road less-traveled and delighted in whatever he discovered along the way. Richard Wayne (Dick) Ojakangas (1932 - 2025) Dr. Richard (Dick) Wayne Ojakangas died peacefully in his sleep on December 16, 2025 at the age of 93. Dick was born November 20, 1932, in Moose Lake, Minnesota, and grew up in Kettle River and Warba. He was very proud of his 100% Finnish heritage. After graduating from Grand Rapids High School, he enrolled as a business major at the University of Minnesota Duluth (UMD), intending to take over the family store in Warba after graduation. However, during his senior year, he took an introductory geology class from Dr. Robert Heller, and switched his major after the first lecture to geology. He joined the Reserve Officer’s Training Corps because he felt it was his patriotic duty to serve his country. After graduation, he was assigned to the USAF base in Upper Heyford, England. He married Finnish beauty Beatrice (Peaches) Luoma and they moved to England within one week after their wedding. Due to his geological expertise, Dick was assigned to be a Petroleum Supply Officer, fueling jets with highly toxic JP4 jet fuel. After two years in the Air Force, he continued his studies in geology, earning a master’s degree from the University of Missouri, and a PhD from Stanford University. Returning to Duluth, “Dr. OJ” enthusiastically taught geology at UMD for 38 years, where he was beloved by many hundreds of students. Dick was renowned as an entertaining and exceptional geology professor. He began each lecture with a Finn joke, and the punchlines were meticulously written on his calendar. His colleagues in the Geology Department were also his extended family and lifelong friends. He retired in 2002. Dick wrote or collaborated on more than 60 scientific publications and several books, including the highly acclaimed Minnesota’s Geology, and Roadside Geology of Minnesota. He was awarded the prestigious Horace T. Morse Award for Distinguished Teachers from the U of M, and received an honorary PhD from the University of Helsinki, Finland. A long-time member of the ILSG, Dick was awarded the Samuel S. Goldich Medal by the Institute in 1984. He was a fixture at annual meetings, leading field trips and giving presentations, either as himself or as one of his alter egos, like the Old Prospector or Herr Dr. Direktor Professor Wolfgang von Schlummerklutz from the World Panzerenkotklotzen Institute in Europe! Dick was a passionate traveler and photographer, doing geological research on all seven continents. His work in Antarctica as part of the United States Antarctic Research Program resulted in having Mount Ojakangas being named after him. In India, he found evidence of the first Archaean glaciation ever discovered. In Finland, he and a colleague were the first to determine the direction that glaciers moved through northern Europe. As a worldrespected geologist and an engaging, highly understandable speaker, he spread his enthusiasm for science by giving lectures on cruise ships from 1978 to 2017, feeding his obsession with traveling the world. Curious and inquisitive, Dick entertained many interests and hobbies. He lived an active life - running several - xiii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Grandma’s Marathon’s (all without training) and cross-country skiing (doing the Birkebeiner 54 km race in Wisconsin many times, also without training). Dick was an avid mushroom hunter on all continents. His wife said that he could ‘find mushrooms, whether they were there or not!’ Known for his generosity, humor, and warm personality, Dick made sure everyone felt included and always sought out strangers, who promptly became his friends. His trademark greeting “Hiya!” and farewell “Cheers!” are remembered fondly by his family and friends. Paul Willard Weiblen (1927 – 2025) Professor Paul Willard Weiblen, 98 years old, died peacefully in the presence of family on Tuesday, December 23, 2025 in St. Paul, Minnesota. PW, to friends, colleagues and students, was born in Miller, South Dakota in 1927. After graduation from high school in 1945, he entered the U.S. Army. After military service he returned to college and earned a B.A. degree at Wartburg College in Waverly, Iowa (1950), and an M.A. in History at the University of Minnesota (1952). PW came into geology in a roundabout way. Apparently, he was in Istanbul, Turkey working as a travel agent for American Express when he encountered a geologist exploring the world for uranium deposits. Consequently, he returned to the University of Minnesota in 1959 to pursue geology. He focused on the metamorphism of the Paleoproterozoic Thomson Formation of east-central Minnesota for his Master’s thesis (1962) and on the geology and petrology of the Bald Eagle intrusion of the Duluth Complex in northeastern Minnesota for his Ph.D. (1965). He stayed at the University in the Geology and Geophysics Department as an Assistant Professor (1965), Associate Professor (1969), Professor (1980), and Professor Emeritus (1997), teaching Minnesota geology and characterizing the minerals of the Duluth Complex with the Minnesota Geological Survey. He was hired specifically to organize and supervise the Department’s new Electron Microprobe Laboratory (1965-1980) in the Space Science Centre. He also served as Curator of the petrology collection (1970-1997) and supervisor of the scanning electron microscope facility (1970-1997). Over his 32 years as a faculty member, Paul’s analytical expertise and unbridled curiosity led him to pursue, and engage others, in many areas of research. The principal focus of his research was on the petrology and mineral deposits of the Duluth Complex. A highlight was a 1980 American Journal of Science paper, co-authored by Minnesota Geological Survey Chief Geologist G.B. Morey, that summarized the stratigraphy, petrology and structure of the Duluth Complex. Another significant area of interest in Paul’s career was lunar petrology. In the early 1970s, he and Edwin Roedder (USGS) confirmed the phenomenon of silicate liquid immiscibility by examining lunar glasses, and terrestrial basalts. In 1978-79, Paul served as lead curator of NASA’s Washington, D.C. lunar sample collection. The focus of Paul’s research in the latter part of his academic career and into his retirement was building and promoting the electric pulse disaggregator (EPD, or “the Zapper”). He was introduced to the EPD and its inventor, Nikolay S. Rudashevsky, during a visit to Russia in 1991.   Recognizing the potential of this instrument to create ultraclean mineral separates for a variety of applications, PW built and installed an EPD at U of M in 1992. He actively promoted it to other scientists who have used it to prepare samples for detrital zircon dating, mineral liberation analyses, and microfossil studies. As a teacher and student advisor, PW was engaging, approachable, and deeply committed to his students. He routinely taught undergraduate and graduate level Igneous Petrology and Optical Mineralogy and offered hands-on classes on electron microprobe analysis. His annual petrology field trips up the Gunflint Trail were legendary. As a graduate advisor, he was open to letting his 11 PhD and 13 MS students develop their own thesis projects, with topics that included igneous petrology; volcanology; structural, metamorphic and field geology; geochemistry, mineralogy, petrography, and economic geology. A particular source of pride was that all but one graduate thesis was based on the geology of Minnesota. PW was awarded the Goldich Medal from the Institute on Lake Superior Geology in 2004 for his lifelong commitment to promoting geologic studies of Minnesota. - xiv - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Ronald Parker Sage (1938 - 2026) Ronald Parker Sage, 87, of Kingsford, MI, passed away peacefully on January 28, 2026, after a battle with numerous health conditions. Ron was born on August 4, 1938, in Pontiac, Michigan. Ron graduated in 1960 with a BSc degree in geological engineering from Michigan Technological University in Houghton. While at MTU, Ron spent most of his free time collecting rocks and minerals in the copper and iron mining districts, earning him the nickname “Rocky”. He was a student of Kiril Spiroff, the “Mad Russian”. Ron held his Alma Mater in high esteem. In the early 1960s, Ron worked for three years as an engineer for the Shell Oil Company in west Texas. His duties included well siting, well logging, well workovers, and other production-related activities. In 1966, Ron graduated with a Master’s degree in Geology from the Colorado School of Mines. It was here that he was first exposed to alkalic rocks, his study topic and thesis being “Geology and Mineralogy of the Cripple Creek Syenite Stock, Teller County, Colorado”. This led to employment with Anaconda American Brass Ltd to investigate CuNi-PGE minerals in the Port Coldwell alkalic complex near Marathon, Ontario. During the summer of 1967, Ron searched for base metals in the Ely greenstone belt in northern Minnesota for Bear Creek Mining. It was in that year that he first met two other greats of Lake Superior geology, Ned Eisenbrey and Gene LaBerge. In 1969, Ron again worked for Anaconda American Brass Ltd., this time north of Lake Superior in the Schreiber greenstone belt, searching for gold and base metals. In the fall of 1969, Ron joined the Ontario Geological Survey, his professional home for over 30 years. Ron’s work for the OGS took him to many parts of the province, but never very far, and never for very long, from Lake Superior. He spent four years on a helicopter reconnaissance in Northern Ontario, then mapped the Slate Islands in Lake Superior, and next worked on a multi-year program to study alkalic rocks north of Port Coldwell along the northern extension of the Trans Superior Tectonic Zone and along the Kapuskasing Structural Zone. In 1978, Ron was assigned to the Michipicoten greenstone belt. Here he spent 10 years mapping Archean supracrustal rocks over approximately 540 square miles, with emphasis on the gold and base metal potential. In 1993, Ron was assigned to a province-wide program of kimberlite documentation to stimulate diamond exploration. Some of this work was again in the Michipicoten area, where diamond-bearing rocks had recently been discovered. Despite his busy professional schedule, Ron was able to complete his PhD degree in 1986 for a thesis submitted to Carleton University in Ottawa, entitled “Alkalic Rock Complexes and Carbonatites of Northern Ontario, and their Economic Potential.” Ron was a long-time ILSG supporter, giving presentations, leading field trips and Co-Chairing the annual meetings in 1987, 1997 and 2006. In 1997, Ron was recognized for his many contributions when he received the Samuel S. Goldich Medal from the Institute on Lake Superior Geology. Charles Edward (Charlie) Blackburn (1940 - 2026) Charlie passed away on Friday March 6, 2026 at the Royal Jubilee Hospital, Victoria, BC. Although he identified himself as a Welshman, having grown up in a small village near Cardiff, Wales, by an accident of fate during the early days of World War II, Charlie was actually born in Kidderminster, England. He went to Swansea University to complete his Bachelor of Science degree in geology. Charlie loved the summer field mapping excursions in Northern - xv - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Norway working towards his goal of becoming a professional geologist. Geology was always his passion and drawing maps, his gift. Charlie emigrated from Wales to Canada and undertook a Master of Science degree at the University of Western Ontario, London, Ontario where he met his wife of sixty years Christine (nee Spence) – also a recent UK immigrant. It was love at first sight. The couple were married after a two-month courtship. They left for Italy where Charlie studied the metamorphic puzzle of the Seisia-Lanzo zone in the Valle d’Aosta at the University of Padua, Italy. He liked that his office was right opposite the Cappella Della Scrovegni – famous for its Giotto frescoes. His time in Italy left him with an enduring love for the people and culture there. Charlie returned to Canada in 1969 and in 1970 accepted a position as a mapping geologist with the Ontario Geological Survey (OGS) in Toronto. As a field geologist, Charlie spent summers of his early career in the bush of northern Ontario and didn’t see too much of his family. As the children grew, Charlie saw the need to be with his family more and so accepted the position of Resident Geologist in Kenora, Ontario. Many of his over 75 OGS publications resulted from his mapping efforts in the Archean greenstone belts of the western Wabigoon Subprovince and other areas in the Kenora District. He was the lead author of the seminal review of the Wabigoon in the 1991 compendium, Geology of Ontario. In the early 90’s, he took a sabbatical from his Resident Geologist duties to return to mapping the Separation Lake area. Charlie retired from the OGS at age 60 after 30 years of service and, with his wife Christine, became co-founder of their consulting company, Blackburn Geological Services. Charlie Chaired the 1985 ILSG annual meeting in Kenora and was on the organizing committee for the 2002 annual meeting, also held in Kenora. He delivered papers and chaired sessions at many ILSG meetings and led field trips to the Separation Rapids rare-element pegmatite field and other locations in the Kenora District, of which he had an encyclopedic knowledge due to his years of mapping and documenting mineral occurrences in the Superior Province. Report of the Chair of the 71st Annual Meeting Amy Radakovich, Allison Severson, Eric Nowariak, Aaron Hirsch, Stacy Saari Mountain Iron, Minnesota The 71st Institute on Lake Superior Geology (ILSG) was held May 14 to 17, 2025 in Mountain Iron, Minnesota at the Mountain Iron Community Center. The meeting was sponsored by the State of Minnesota’s Iron Range Resources and Rehabilitation agency, Bayside Geoscience, the Geological Society of Minnesota, the Mesabi Range Geological Society, George Hudak Geosciences, PLLC, and the University of Minnesota Duluth’s (UMD) Swenson College of Science and Engineering Earth and Environmental Sciences department, as well as individual contributors Roger Anderson, Allan MacTavish, Dave Dahl, Tom Erickson, and Barry Frey. The meeting was cochaired by Amy Radakovich, Allison Severson, Eric Nowariak, and Aaron Hirsch of the Minnesota Geological Survey (MGS), and Stacy Saari of the Minnesota Department of Natural Resources (MNDNR). Patrice Cobin and Julie Stark of Michigan Technological University served as registrars for the meeting. The institute was attended by a total of 137 participants of which 25 were students. Generous donations from the following individuals helped provide a reduced registration and field trip price for students: Kate Clover, Jim and Isabel DeGraff, Tom Erickson, Tom Fitz, Aaron Hirsch, Paula Leier-Engelhardt, Bob Mahin, Vince and Susan Matthews, Jim Miller, Allison Severson, Mark and Lauri Severson, John Verhoeven, and Gerry White. The 71st meeting consisted of two full days of technical sessions, which ran from Thursday morning, May 15 through Friday afternoon, May 16th. The meeting also held pre-and post-meetingfield trips on May 14th and May 17th. A total of 51 presentations were subdivided into 8 technical sessions; 6 technical sessions for 26 oral presentations (of which 1 was presented by a student), and 2 poster technical sessions with a total of 23 poster presentations (of which 14 were presented by students). The chairs continued the previous meeting’s precedent of including two poster sessions to allow both attendees and judges more time to review the posters. The first th - xvi - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 presentation of the technical sessions was given by Mark Smyk (OGS - retired; Goldich Medalist in 2005) who gave the citation for Robert Bell, the 2025 Pioneer of Lake Superior Geology. Bell is the 6th person to be recognized for their contributions to Lake Superior Geology prior to the initiation of the ILSG. The technical sessions of the 71st annual meeting of ILSG were published in 2025 as Part 1 of Proceedings Volume 71 (95 pages). Five Doug Duskin Best Student Paper Awards were given for student oral and poster presentations as judged by the 2024 Student Paper Awards Committee chaired by Aaron Hirsch (MGS). PhD student poster awards were given to Zsusanna Allerton and Madelyn Banks. Undergraduate student poster awards were given to Celia Cortopassi and Lyndsie Vickers. Omar Khali Droubi received the best oral presentation award. The 71st ILSG also awarded 12 Eisenbrey Student Travel and Participation Awards to help defray the cost of travel to and participation in the ILSG professional meeting for undergraduate and graduate students. The awardees were Drew Casper, Haley Johannesen, Mary Elizabeth Shalifoe, Linsey Hula, Omar Khalil Droubi, Samara Gries, Renee Jeutter, Aidan Kwiatkowski, Celia Cortopassi, Lyndsie Vickers, Zsuzsanna Allerton, and Bekah Thomson. As usual, field trips were a highlight of the 71st ILSG. Mountain Iron’s close proximity to exposures of Archean, Paleoproterozoic, and Mesoproterozoic rocks made it a prime location to run numerous excellent field trips. The meeting offered 8 field trips which included 4 pre-meeting trips on Wednesday May 14, and 4 post-meeting trips on Saturday May 17. Seven field trips focused on the varied Precambrian geology of northeastern Minnesota, and one trip highlighted the unique Quaternary features of the region. Seven of the eight field trips were able to run, with one cancelled due to active wildfires in the field trip area. The remaining 7 field trips were well attended. There were 130 registrants for the field trips, excluding leaders, representing over 100 different individuals (some registrants took multiple trips). Pre-meeting trip 1 was a “Transect through the Quetico subprovince of northern Minnesota,” led by Eric Nowariak (MGS) and Mark Jirsa (MGS-retired). Pre-meeting trip 2 was led by Mark Severson (Natural Resources Research Institute, Teck - retired), Cullen Phillips (New Range Copper Nickel), and Kevin Boerst (Twin Metals Minnesota) and highlighted “Drill Core from three Cu-Ni deposits of the Duluth Complex.” Pre-meeting trip 3 asked the question “How do you make iron and/or manganese in Proterozoic iron formation?” and was led by Alex Steiner and Dean Peterson (Big Rock Exploration) and Latisha Brengman (University of Minnesota Duluth [UMD]). Pre-meeting trip 4 was led by George J. Hudak (University of Minnesota; George Hudak Geosciences, P.L.L.C) and Zsuzsanna Allerton and Annia Fayon (University of Minnesota) and highlighted “New geological insights into the genesis of iron ores at Lake Vermillion-Soudan Underground Mine State Park.” Post-meeting trip 5 traveled to numerous “Neoarchean alkalic intrusions in the Wawa and Quetico subprovinces” and was led by Terry Boerboom (MGS-retired) and Amy Radakovich (MGS). Mark (NRRI, Teck - retired), Allison (MGS), and Lauri (earth science teacher - retired) Severson planned to lead post-meeting trip 6 focused on a “Unique Keweenawan inclusion (Colvin Creek) in the Duluth Complex.” However, the trip was cancelled due to wildfire conditions, and participants were invited to join other trips or receive a refund. Post-meeting trip 7 led by Dean Peterson (Big Rock Exploration) and George Hudak (University of Minnesota; George Hudak Geosciences, P.L.L.C) visited numerous “Classic outcrops of northeastern Minnesota” Field trip 8 was led by Phil Larson (Vesterheim Geoscience, PLC), Andrew Breckinridge (University of Wisconsin - Superior), and Howard Mooers (UMD) and focused on Glacial Lake Norwood and the Koochiching Lobe.” Field trip guides were published in 2025 as Part 2 of the Proceedings Volume 71 (200 pages). A catered welcome reception was held at the Mountain Iron Community Center on Wednesday evening, May 14, after all of the pre-trips returned. The event was well attended, and offered a chance for meeting attendees to reconnect with colleagues and friends prior to the start of technical sessions. Steve Solkela provided entertainment for a portion of the evening. The annual ILSG social and banquet were hosted at the Mountain Iron Community Center on Thursday evening, May 15, 2025. Ninety-three people were in attendance at the sold-out banquet. After introductions - xvii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 and announcements, Mark Puumala announced the location of the 2026 meeting as Thunder Bay, Ontario. The program continued with ILSG awarding the prestigious Goldich Medal to the very deserving Robert Michael (Mike) Easton (Ontario Geological Survey), who unfortunately could not be present at the meeting. Wouter Bleeker (Geological Survey of Canada) provided the citation for Mike, highlighting Mike’s long tenure with the OGS, his impressive publication record, and his contributions to ILSG. Another highlight of the banquet was the keynote presentation by Pete Kero, P.E., Senior Environmental Engineer with Barr Engineering Co and visionary behind the award-winning Redhead Mountain Bike Park in Chisholm, Minnesota. His fascinating talk entitled “Mine to Mountain Bike Mecca: The story of the Redhead Mountain Bike Park” detailed the transformation of ten idled open pit iron mines in northeast Minnesota into a world-class recreation destination for mountain biking, hiking, and paddling. Kero fielded many questions from the engaged audience and sold and autographed his book Minescapes: Reclaiming Minnesota’s Mined Lands after the keynote presentation, which ended the banquet program. The Institute’s Board of Directors met on Thursday May 15, 2025 to discuss ILSG business and approve the 2026 meeting location. The meeting was attended by Amy Radakovich (Board Chair and Assistant Treasurer), Ted Bornhorst, Carsyn Ames, Peter Hollings (Secretary), and Mark Jirsa (Treasurer). Guests at the meeting were the meeting co-chairs Allison Severson, Eric Nowariak, Aaron Hirsch, and Stacy Saari and also Mark Puumala, the Chair of the proposed 2026 Thunder Bay meeting (approved by the board - see below). Michael Easton was unable to attend. Institute’s Board of Directors meeting notes were taken by ILSG Secretary Hollings, which are as follows: 1. Accepted report of the Chairs for the 70th ILSG, as published in the Proceedings volume, and minutes of last Board meeting, May, 2024 (Hollings). 2. Received and discussed 2024-2025 ILSG Financial Summary (Jirsa/Radakovich). Final approval tabled for Email vote after necessary revisions are made to balances as listed 3. Received, discussed, and accepted 2024-2025 report of the Secretary (Hollings). 4. Approved Alli Severson as on-going ILSG Board member and Pete Hinz and Mark Puumala as coChairs. 5. Discussed and approved appointing Amy Radakovich as the Institute Treasurer. This was subsequently approved by the Membership. Mark Jirsa was thanked for his 31 year service to the Institute. 6. Discussed and approved replacing Dean Peterson as the “member from industry” on Goldich Committee (end of term 2025) with Phil Larson. 7. Approved Thunder Bay as the site for the 72nd annual ILSG meeting. The meeting will be Chaired by Pete Hinz and Mark Puumala with tentative dates of May 19 to 23. 8. A number of future meeting locations were discussed including Grand Marais (Jim Miller), Baraboo (Esther Stewart & Carsyn Ames) and Marquette. 9. The revised Eisenbrey guidelines were discussed and approved with edits. Changes expand the list of expenses which are eligible for reimbursement from the Eisenbrey award (ex: registration fees, meals, lodging, and transportation are all now included) 10. There was discussion over the format and page limits for the abstracts. It was agreed that the two page limit would be maintained. 11. The cost of hosting the meeting registration through MTU was discussed. MTU currently charges 12% of the total registration sales as their fee. It was agreed that the hosts of each meeting would evaluate possible hosting options and pick the one that worked best for them. Puumala indicated that next year the hosts would likely go with a Canadian registrar so that registration fees could be charged in Canadian dollars 12. The cost of printing the Proceedings and Field Guide volumes was discussed. It was agreed that future meeting Chairs would explore the possibility of making the full printed volumes a paid option for participants - xviii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 and providing only the guides for individual trips. 13. The ongoing storage of ILSG poster boards and easels was discussed. MTU has stored them for the last ~10 years but can no longer offer to do that. Boards and easels were stored for the past year at the Minnesota Geological Survey, but there is no room for permanent storage there. It was suggested that the storage and transport of the posters and easels become the responsibility of the meeting hosts, such that after each ILSG meeting, the boards and easels would leave with the host of the following year’s meeting. This way storage and transport costs can be built into the next year’s meeting costs. Thunder Bay hosts do not need boards next year and did not want to take them across the border given recent border crossing issues. It was suggested that ILSG perhaps have two sets of boards and two sets of easels - one that resides in Canada and one that resides in the USA. Carsyn Ames volunteered to store the boards and easels at the Wisconsin Geological Survey for the next year, delaying the need to make a final decision. Our large, five-person committee allowed us to divide-and-conquer the innumerable tasks to make The 71st annual ILSG meeting a great success. We were proud to continue the long-standing tradition of bringing people together from many states and provinces to share and learn about the fascinating geology of the Lake Superior region, both in the meeting and ‘on the rocks.’ The co-chairs would like to thank the many people and organizations who made the meeting possible, including the Mesabi Range Geological Society and UMD students who ran the registration table and helped with merchandise sales, and the numerous individuals who offered to drive rental or personal vehicles on our fieldtrips. The Sawmill supplied all meeting and field trip food, Caribou provided coffee and tea for the field trips, and Peplinjack’s Bakery supplied the delicious field trip pastries. Lastly, we would like to thank the numerous generous donors who donated hundreds of rock and mineral specimens, books, and maps that made up the biggest and most profitable book sale and silent auction in ILSG memory. The sale and auction netted a total of approximately $4,500 which will be used to fund student participation at subsequent meetings. We look forward to seeing everyone next year in Thunder Bay! Respectfully submitted, Amy Radakovich, Allison Severson, Eric Nowariak, Aaron Hirsch, and Stacy Saari Co-chairs, 71st Institute on Lake Superior Geology Eisenbrey Student Travel Awards The 1986 Board of Directors established the ILSG Student Travel Awards to support student participation at the annual meeting of the Institute. The name “Eisenbrey” was added to the award in 1998 to honor Edward H. Eisenbrey (1926-1985) and utilize substantial contributions made to the 1996 Institute meeting in his name. “Ned” Eisenbrey is credited with discovery of significant volcanogenic massive sulfide deposits in Wisconsin, but his scope was much broader - he has been described as having unique talents as an ore finder, geologist, and teacher. These awards are intended to help defray some of the direct travel costs of attending Institute meetings, and include a waiver of registration fees, but exclude expenses for meals, lodging, and field trip registration. The number of awards and value are determined by the annual Chair in consultation with the Secretary and Treasurer. Recipients will be announced at the end of the annual meeting. The following general criteria will be considered by the annual Chair, who is responsible for the selection: 1) The applicants must have active resident (undergraduate or graduate) student status at the time of the annual meeting of the Institute, certified by the department head. 2) Students who are the senior author on either an oral or poster paper will be given favored consideration. 3) It is desirable for two or more students to jointly request travel assistance. 4) In general, priority will be given to those in the Institute region who are farthest away from the meeting location. - xix - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 5) Each travel award request shall be made in writing to the annual Chair, and should explain need, student and author status, and other significant details. Successful applicants will receive their awards during the meeting. Joe Mancuso Student Research Awards The 2005 Board of Directors established the ILSG Student Research Fund with $10,000 US from the Institute’s general fund to encourage student research on the geology of the Lake Superior region. A minimum of two awards of $500 US each for research expenses (but not travel expenses) will be made each year. Students are expected to present their research orally or during a poster session at an ILSG meeting. The award winners will also be automatically eligible for the Eisenbrey Travel Awards. To allow the fund to grow, the Fund will receive one-half of any additional proceeds from each annual meeting, after all other commitments and expenses are covered. • The ILSG Board of Directors will be responsible for selecting a minimum of two awards each year. The ILSG Treasurer will issue the awards. • The ILSG Student Research Fund is available for undergraduate or graduate students working on geology in the Lake Superior region. • The applications are due to the ILSG Secretary by August 31st of each year. Awards will be made by October 1st of each year. • Names of the award recipients will be announced at the next annual meeting and posted on the ILSG website. • Details of the application process can be found on the ILSG web site. • The proposal will need to be signed by the researcher’s supervisor. The 2012 Board of Directors approved modification of the fund’s name, adding “Mancuso” to reflect the many contributions of Joseph Mancuso to the organization and sizeable donations made in his name. “Doc Joe,” as he was known by his students, taught geology for 36 years at Bowling Green State University, Ohio. He advised many graduate students in field-oriented research, and frequently brought them to Institute meetings. Joe was the 2007 Goldich Medalist. In fall 2025, the ILSG Board of Directors selected two students to be granted research funding of $500 each from the Joe Mancuso Student Research Fund. The awardees were: Kathryn Akin, University of Minnesota- Twin Cities Alyssa Hellrung, University of Wisconsin Doug Duskin Student Paper Awards Each year, the Institute selects the best of student presentations and honors the presenters with a monetary award. Funding for the award is generated from registrations of the annual meeting, and from generous donations to the fund in honor of Doug Duskin—an exploration geologist and long- time friend of the Institute. The 2012 ILSG Board of Directors approved adding Doug’s name to the award to acknowledge his contributions and distribute those donations in a manner that would have pleased him. The Duskin Student Paper Committee is appointed by the Meeting Chair. Criteria for best student paper—last modified by the Board in 2001—follow: 1) The contribution must be demonstrably the work of the student. 2) The student must present the contribution in-person. 3) The Student Paper Committee shall decide how many awards to grant, and whether or not to give separate awards for poster vs. oral presentations. - xx - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 4) In cases of multiple student authors, the award will be made to the senior author, or the award will be shared equally by all authors of the contribution. 5) The total amount of the awards is left to the discretion of the meeting Chair in conjunction with the Secretary, but typically is in the amount of about $500 US (increase approved by Board, 10/01). 6) The Secretary maintains, and will supply to the Committee, a form for the numerical ranking of presentations. This form was created and modified by Student Paper Committees over several years in an effort to reduce the difficulties that may arise from selection by raters of diverse background. The use of the form is not required but is left to the discretion of the Committee. 7) The names of award recipients shall be included as part of the annual Chair’s report that appears in the next volume of the Institute. Student papers will be noted on the Program. 2026 Student Paper Awards Committee Emily Smyk - Bayside Geoscience Justin Jonsson - Ontario Geological Survey Nick Swanson-Hysell - University of Minnesota Board of Directors Board appointment continues through the close of the meeting year shown in parentheses, or until a successor is selected Peter Hinz and Mark Puumala, Co-Chairs (2026-2029) - Ontario Geological Survey, Retired Alli Severson (2025-2028) - Minnesota Geological Survey Ted Bornhorst (2024-2027) - Michigan Tech, Houghton Carsyn Ames (2023-2026) - Wisconsin Geological & Natural History Survey, Madison Amy Radakovich, Treasurer (2025-2028) - Minnesota Geological Survey Peter Hollings, Secretary (2024-2027) - Lakehead University Local Committee Chairs Peter Hinz and Mark Puumala - Ontario Geological Survey, Retired Organising Committee Robert Cundari - Ontario Geological Survey, Thunder Bay, Ontario Al MacTavish - Thunder Bay, Ontario Mark Smyk - Lakehead University, Thunder Bay, Ontario Pete Hollings - Lakehead University, Thunder Bay, Ontario Jim Miller - Thunder Bay, Ontario - xxi - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Field Trip Leaders and Guidebook Authors Field trips have been the mainstay of the ILSG since its inception 72 years ago. We give special thanks to the field trip leaders and guidebook authors who volunteered their time and talent in carrying that tradition forward. Trips 1 & 4: Classic” Geological Sites in the Thunder Bay Area - Mark Smyk (Lakehead University) and Mark Puumala (Geological Consultant) Trip 2: Geology of the Quetico Subprovince and Shebandowan greenstone belt north of Thunder Bay - Riku Metsaranta and Gaetan Launay (Ontario Geological Survey) Trip 3: Geological assemblages, regional structural framework and tectonic evolution of the Neoarchean Shebandowan greenstone belt - Dorothy Campbell, Justin Jonsson and Vittoria D’Angelo (OGS Resident Geologist Program) Trip 5: Archean Geology and Metallogeny of the Rainy Lake Wrench Zone - K. Howard Poulsen (Geological Consultant) Trip 6: Amethyst Deposits of Thunder Bay - Steve Kissin (Lakehead University) and Greg Paju (OGS Resident Geologist Program) - xxii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Technical Program Wednesday May 20 (Parking Lot G14, Lakehead University) 8:00 a.m. Field Trip 1: “Classic” Geological Sites in the Thunder Bay Area Leaders: Mark Smyk and Mark Puumala 8:00 a.m. Field Trip 2: Geology of the Quetico Subprovince and Shebandowan greenstone belt north of Thunder Bay Leaders: Riku Metsaranta and Gaetan Launay 8:00 a.m. Field Trip 3: Geological assemblages, regional structural framework and tectonic evolution of the Neoarchean Shebandowan greenstone belt Leaders: Justin Jonsson and Vittoria D’Angelo 5:00 p.m. Return of Trips 1-3 4:00 p.m. - 8.00 p.m. Registration (Faculty Lounge, Lakehead University) 6:00 p.m. - 9.00 p.m. Ice Breaker Social, Poster Setup and Core Shack (Faculty Lounge, Lakehead University) Thursday May 21 7:30 a.m. - 4:00 p.m. Registration (Faculty Lounge, Lakehead University) 8:30a.m. - 9:00 a.m. Introductory Remarks (Room UC0050, Lakehead University) Technical Session I NOTE: Asterisk * denotes a student eligible for a Best Student Paper Award Session Chairs: Mark Puumala and Jim Miller 9:00 a.m. Stephan, T., Phillips, N., and Hollings, P. Timing and conditions of magmatism, metamorphism, and strain partitioning in the western Shebandowan Greenstone Belt (Superior Province) 9:20 a.m. MacDonald, P., Hastie, E., Malegus, P., Kamo, S., Hamilton, M. and Marsh, J. Implications of recent geochronology on the regional geology and timing of gold mineralization in the Red Lake greenstone belt, Ontario 9:40 a.m. Hollings, P., Vrzovski, J., Cooke, D. and Gorner, E. Using epidote and chlorite mineral chemistry to extend the alteration footprint around the Hemlo Au deposit, N. Ontario 10:00 a.m. - 10:30 a.m. Coffee Break, Poster Session and Core Shack 10:30 a.m. Tiitto*, H., Phillips, N., and Stephan, T. Deformation processes in a mid-crustal strike-slip shear zone: Insights from the Archean Quetico Shear Zone, Superior Province, Canada 10:50 a.m. Sheshnev*, V., Hollings, P., Tolley, J., Angombe, M., Deller, M. and Stern, R. Whole Rock and Mineral Chemistry of the Eagle’s Nest Intrusion, McFaulds Lake Greenstone Belt, Ontario, Canada: Insights into the Origin and Paragenesis - xxiii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 11:10 a.m. Carlton*, K., Tikoff, B. and Nachlas, W. An introduction to the northwestern Huron Mountains of the Upper Peninsula, Michigan: field relations and preliminary structural interpretations 11:30 p.m. - 1:00 p.m. Lunch Break, Poster Session and Core Shack (ILSG Board Meeting by invitation) Technical Session II Session Chairs: Esther Stewart and Phil Larson 1:00 p.m. Salerno, R., Cannon, W. F., Thompson, J., Souders, A., Vervoort J. and Hillenbrand, I. Reassessing variations in metamorphism across the Penokean orogen in Northern Michigan: Part 1, new Pressure-Temperature-Time-Deformation constraints 1:20 p.m. Cannon, W. F., Salerno, R., Drenth, B. and Bedrosian, P. Reassessing variations in metamorphism across the Penokean orogen in Northern Michigan: Part 2, Reinterpreting metamorphic nodes 1:40p.m. Hirsch, A. Can we improve the bouguer gravity resolution in the Cuyuna Range? Increasing gravity measurements in a region of high gravity station density. 2:00 p.m. - 2:30 p.m. Coffee Break, Poster Session and Core Shack 2:30 p.m. Allerton, P. and Hudak, G. Characterization of hematite ore from former Ely mines, NE Minnesota 2:50 p.m. Steiner, R.A., Watson, N., Riley, J., Hammer, M., Thole, J., Feinberg, J., Sandri, H. and Savage, B. Oxidation to Ores: Petrological Insights into Supergene Manganese Enrichment at the Emily Deposit, Minnesota 3:10 p.m. Hagedorn, G. Ice flow history, surficial geology, and till composition of Georgia Lake area, northwestern Ontario Poster Session 3:30 - 5:00 p.m. 6:00 p.m Annual Banquet and Award Presentation (Faculty Lounge, Lakehead University) Announcement of 73rd Annual Meeting Location 2026 Goldich Award Presentation to Bill Rose 2026 Quiz night Meeting participants not registered for the banquet are welcome to attend the quiz night - xxiv - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Friday May 22 9:00 a.m. - 12:00 p.m. Registration Technical Session III Session Chairs: Shannon Zurevinski and Therese Pettigrew 8:30 a.m. Beyer, S., Cutts, J., Hnatyshin, D., Powell, J., Camacho, A., Cawood, T. and Drever, G. Preliminary geochronology of lithium pegmatites and host rocks, Archean Superior Province, northwestern Ontario 8:50 a.m. Quigley, A., Mahin, R., and Gamet, N. Critical Mineral Potential of the Watersmeet Gneiss Dome, MI USA 9:10 a.m. Bleeker, W. and Wodicka, N. Improved Precision and Better Accuracy: SHRIMP-II Detrital Zircon Analysis of Samples Across the Stratigraphy of the Midcontinent Rift 9:30 a.m. Easton, R.M. and Kamo, S. The Badgerow complex, a Midcontinent Rift-related REE-Zr-rich peralkaline intrusion in the Grenville Province near Verner, Ontario 9:50 a.m. - 10:20 a.m. Coffee Break, Poster Session and Core Shack 10:20 a.m. Nitescu, B., Torres, D., and Gaona, J.. Models of the regional gravity and magnetic anomalies associated with the Nipigon Embayment 10:40 a.m. Bain, W. and Hollings, P. Coeval silicate melt and PGE-bearing salt melt inclusions in the Thunder and Seagull intrusions, Ontario: An overview of evidence and data processing challenges 11:00 a.m. Drost, A. and Heggie, G. A new look at the Seagull mafic-ultramafic Intrusion and potential hydrogen and helium accumulations 11:20 a.m. Swanson-Hysell, N., Zhang, Y., Mohr, M. and Schmitz, M. Linking the Southwestern Laurentia large igneous province and rapid Duluth Complex emplacement through mantle plume dynamics 11:40 p.m. - 1:00 p.m. Lunch Break, Poster Session and Core Shack Technical Session IV Session Chairs: Wouter Bleeker and Peter Hinz 1:00 p.m. Smith, J., Kaski, K., Tschirhart, V. and Enkin, R. Integrating petrophysical data with full tensor magnetic gradiometry for improved interpretation and modelling of remanently magnetized intrusions in the Midcontinent Rift 1:20 p.m. Peterson, D., Steiner, A., Sweet, G. and Boucher, C. Physical Magmatic System Interpretation of the Marathon Cu-Pd Deposit, Coldwell Complex, Ontario 1:40 p.m. Smyk, E., Dolega, S., Churchley, J. and Flank, S. Optimizing data collection for better geological interpretations and adding value to your project - xxv - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 2:00 p.m. Lizzadro-McPherson, D., Vye, E., Degraff, J., and Rose, W. Interactive Geospatial Geoheritage: Efforts to Support Place-based Exploration and Digitally Preserve Keweenaw’s Geoheritage 2:20 p.m. - 2:50 p.m. Coffee Break, Poster Session and Core Shack 2:50 p.m. Degraff, J., Hiltunen, L., Lafreniere, D., Lizzadro-McPherson, D., Vye, E., Cowling, B., Bornhorst, T. and Rose, W. Digital Preservation and Enhanced Utility of Exploration Core Descriptions from the Keweenaw Copper District, Michigan: Progress toward a Map-based Web Portal 3:10 p.m. Stone, A., Lizzadro-McPherson, D. amd Vye E. Rocks and Roots: The Role of Geoheritage in Biodiversity Stewardship 3:30 p.m. Smyk, M., Hodge, J. and Robillard, C. Pukaskwa Redux: Revisiting and Reconnecting with Superior’s Wild North Shore 3:50 p.m Presentation of Best Student Paper Award and Eisenbrey Awards 5:00 p.m. Field Trip 5: Archean Geology and Metallogeny of the Rainy Lake Wrench Zone Leader: Howard Poulsen Parking Lot G14, Lakehead University Poster Presentations Akin*, K. and Swanson-Hysell, N. Constraining the 3-D Geometry of the Duluth Complex, MN, Using Magnetic Fabrics and Paleomagnetic Data Angombe, M., Phillips, N., Hollings, P., Stephan T., Sheshnev, V., Deller, M. and Smith, A. Decoding Shear Zone Evolution in the McFaulds Lake Greenstone Belt, Ontario: Constraints on CrystalPlastic Deformation and Timing from in-situ Titanite U–Pb Thermochronology Bilboe*, M., Zurevinski, S. and Conly, A. Quartz Trace Element and TEM Analysis of Selected Economic LCT Pegmatites Buchholz, T., Falster, A. and Simmons, W. Update to: a complex F-rich alkalic pegmatite in the pyroxene syenites of the Stettin Complex, Wausau Complex, Marathon County, Wisconsin Chaisson*, A., Smyk, M. and Zurevinski, S. Petrography and Geochemistry of the Mound Lake Pluton, Northwestern Ontario Duffy*, P., Brengman, L. and Eyster, A. Integrated X-Ray Diffraction and Petrography Document Carbonate Mineral Heterogeneity and Hematite Mineralization in the Upper Biwabik Iron Formation, MN Ellison*, K ., Cisneros, J., Eyster, A. and Brengman1, L. Comparing mineralogy along a surface to depth transect of the ~2.7 Ga North Limb Soudan Iron Formation, NE Minnesota - xxvi - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Erickson, S., Fayon, A., Allerton, Z. and Hudak, G. Middle school virtual field trip lessons materials for Archean formations of Lake Vermilion-Soudan Underground Mine State Park Gilberg*, N., Fralick, P. and Li, Z. Geochemical Constraints on Mn Cycling in the Paleoproterozoic Gunflint Formation Gosai*, M., Fralick, P. and Li, Z. Modified Sequential Iron Extraction Method for Analyzing Rare Earth Elements in Banded Iron Formations Grauch, V. and Heller, S. Time-to-depth conversion of seismic-reflection data from eastern Lake Superior and implications for the eastern arm of the Midcontinent Rift Harding*, M. and Hollings, P. Geochemistry, Petrogenesis, and Mineralization of the Makwa Deposit, Bird River Sill Hellrung*, A., Droubi, O., Ruggles, C. and Bonamici, C. Using Anisotropy of Magnetic Susceptibility and U-Pb Geochronology from the Bush Lake Granite, Florence County, WI to Understand Post-Penokean Continental Growth Jonsson, J. and Li, Z. Petrographic Study of Granular Iron Formation in the Gunflint Formation: Evidence for Well-Oxygenated Surface Waters Marin López*, V., Brengman, L., Eyster, A., Mitchell, J., Pu, X., Mangum, J. and Walker, P. Quantitative analysis of iron mineral composition and crystal sizes in the contact metamorphosed Biwabik iron formation and the Bald Eagle intrusion, NE, MN, USA Nowak*, R., Deering, C. and Essig, E. Origin of the World-Class Eagle, Eagle East, and Tamarack Ni-Cu-PGE Deposits and comparative analysis with other Midcontinent Rift- and Siberian Trap-related intrusions Nowariak, E. and Severson, A. Bedrock Geology of the Ericsburg NW, Ericsburg NE, Ray SW, and Ray SE Quadrangles, St. Louis and Koochiching Counties, Minnesota Paliewicz, C., Post, S. and Thakurta, J. Petrographic, geochemical, and mineralogical analyses of manganiferous iron formations and associated lithologies at the Cuyuna Range, central Minnesota Saini-Eidukat, B., Chittick, S. and Nesheim, T. Current geologic and geophysical research on the Precambrian basement of eastern North Dakota, USA Stewart, E., McNall, N., Hart, D., Ames, C., Chase, P., Stewart, E. and Graham, G. Subsurface mapping of the late Ordovician Maquoketa Group in eastern Wisconsin using airborne electromagnetic and well data Tolley, J. and Hollings, P. Variations in Olivine Major Element Composition Across the Midcontinent Rift System NOTE: Asterisk * denotes a student eligible for a Best Student Paper Award - xxvii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Saturday May 23 (Parking Lot G14, Lakehead University) 8:00 a.m. Field Trip 4: “Classic” Geological Sites in the Thunder Bay Area Leaders: Mark Smyk and Mark Puumala 8:00 a.m. Field Trip 6: Amethyst Deposits of Thunder Bay Leaders: Steve Kissin and Greg Paju 5.00 p.m. Return of Trips 4 & 6 Sunday May 24 (Parking Lot G14, Lakehead University) 5.00 p.m. Return of Trip 5 - xxviii - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Constraining the 3-D Geometry of the Duluth Complex, MN, Using Magnetic Fabrics and Paleomagnetic Data AKIN, Kathryn1 and SWANSON-HYSELL, Nicholas1 1 Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA The Midcontinent Rift developed within the interior of Laurentia during a period of extension and magmatism from 1109 Ma to 1084 Ma (Swanson-Hysell et al., 2019). Emplaced during the development of the Midcontinent Rift, the Duluth Complex is interpreted as the second-largest exposed mafic intrusive complex on Earth. The Duluth Complex is composed of an anorthositic series and a layered series of gabbro and troctolite cumulates (Figure 1; Miller et al., 2002). Many studies have been conducted on the geology, mineralization, structure, timing, and mechanisms of emplacement of the Duluth Complex and nearby Beaver Bay Complex and North Shore Volcanic Group, but there is still some uncertainty surrounding the thickness, and therefore overall volume, of the Duluth Complex. Figure 1: Map of the Duluth Complex field location in northeastern Minnesota. Red diamonds represent sampling locations from the August 2025 field season. Geological map data from Bauer (2022). The tilt of the Duluth Complex is not well-constrained in the anorthositic series, given the absence of macroscopic igneous foliation, so this research is focused on developing data on the magnetic fabrics of the Duluth Complex along a transect to constrain the igneous foliation and to use these data to develop new estimates of the tilt and thickness of the intrusion. Anisotropy of magnetic susceptibility (AMS) is sensitive to changes in mineral alignment and, therefore, is used to constrain igneous foliation, especially in samples that do not display an obvious macroscopic fabric in the field (Schmidt et al., 2007). Remanent magnetization data collected and compared with the expected directions of contemporaneous volcanics can also provide further insight into tilt. Together, the new susceptibility and remanence data will provide important petrophysical information for interpreting upcoming USGS aeromagnetic surveys currently being flown in -1- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 northeastern Minnesota. New constraints on the intensity of remanent magnetization and its ratio with susceptibility (the Koenigsberger ratio) will be added to the Rock Properties database maintained by the Minnesota Geological Survey (Chandler et al., 2011). REFERENCES Bauer, E.J., Jirsa, M.A., Block, A.R., Boerboom, T.J., Chandler, V.W., Peterson, D.M., Wagner, K.G., McDonald, J.M., Dengler, E.L., Meyer, G.N., and Hamilton, J.D., 2022, C-54, Geologic Atlas of Lake County, Minnesota: Minnesota Geological Survey: University of Minnesota Digital Conservancy, https://hdl.handle.net/11299/254822. Chandler, V.W., and Lively, R.S., 2011, Density, Magnetic Susceptibility, and Natural Remanent Magnetization of Rocks in Minnesota: An MGS Rock Properties Database: Minnesota Geological Survey, https://hdl.handle.net/11299/175580 Miller, J.D., Green, J.C., Severson, M.J., Chandler, V.W., Hauck, S.A., Peterson, D.M., and Wahl, T.E., 2002, RI-58 Geology and mineral potential of the Duluth Complex and related rocks of northeastern Minnesota:, https://hdl.handle. net/11299/58804. Schmidt, P.W., McEnroe, S.A., Clark, D.A., and Robinson, P., 2007, Magnetic properties and potential field modeling of the Peculiar Knob metamorphosed iron formation, South Australia: An analog for the source of the intense Martian magnetic anomalies? Journal of Geophysical Research: solid Earth, v. 112, doi:10.1029/2006JB004495. Swanson-Hysell, N. L., Ramezani, J., Fairchild, L. M., and Rose, I. R., 2019, Failed rifting and fast drifting: Midcontinent Rift development, Laurentia’s rapid motion and the driver of Grenvillian orogenesis: GSA Bulletin, vol. 131, pp. 913–940, doi:10.1130/b31944.1. Swanson-Hysell, N.L., Hoaglund, S.A., Crowley, J.L., Schmitz, M.D., Zhang, Y., and Miller Jr., J.D., 2021, Rapid emplacement of massive Duluth Complex intrusions within the North American Midcontinental Rift: Geology, vol. 49, pp. 185-189, https://doi.org/10.1130/G47873.1. -2- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Characterization of hematite ore from former Ely mines, NE Minnesota ALLERTON, P. Zsuzsanna1 and HUDAK, J. George1,2,3 1 2 3 Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455, USA Earth and Environmental Sciences, University of Minnesota, Duluth, MN 55812, USA George Hudak Geosciences P.L.L.C., Duluth, MN 55804, USA The hematite ore deposits located in the Vermilion Range in Ely, northeastern Minnesota, represent some of the highest-grade iron ores ever mined in the United States. These deposits occur within Neoarchean (~2.7 Ga) Algoma-type banded iron formations (BIFs) in the Ely Greenstone belt which is dominantly composed of greenschist facies metamorphosed volcanic, sedimentary and intrusive rocks. The ore bodies, exploited in underground mines such as the Zenith, Pioneer, Sibley and others, consist of steeply dipping, tabular to lens-shaped masses of massive hematite that replace jaspilitic BIF. These bodies are enclosed within greenstone wall rocks and are often localized along brecciated zones within a complex regional fold structure. Machamer’s 1968 study of the Zenith mine details the textural varieties of high-grade hematite ore formed by hypogene hydrothermal replacement of jaspilitic BIF. His petrographic and field descriptions identify five prominent ore textures that reflect stages of replacement, brecciation, cementation, and zoning. The characterization and documentation of these five textures at the Pioneer and Sibley mines are the focus of this research. Hematite ore samples utilized for this study were obtained from the Minnesota DNR Hibbing Core Library. Zenith mine ore samples were not available for re-analysis. Ore texture types described are consistent with the nomenclature developed by Machamer (1968). Type 1, the most abundant texture, is a dense, uniform material composed almost entirely of crystalline hematite, representing the primary massive replacement ore (Figure 1A). Type 2 texture consists of brecciated fragments of type 1 ore cemented by a later generation of secondary crystalline hematite, which commonly contains minute vugs lined with small hematite crystals and appear in a reticulated pattern resembling a boxwork (Figure 1B). Type 3 texture is similar to type 2 but features a cement composed dominantly of carbonate minerals (primarily ankerite or siderite) rather than hematite (Figure 1C). Type 4 texture is composed largely of carbonate minerals; it may contain fragments of earlier type 1 hematite material as well as earlier-formed carbonates, reflecting deeper or more advanced carbonate replacement (Figure 1D). Type 5 texture consists principally of magnetite with variable amounts of carbonate minerals, hausmannite (manganese oxide, Mn3O4) and pyrite; this type is generally non-merchantable due to its lower iron content or higher sulfur. The great bulk of the ore mined at Zenith (and similarly at Sibley mine) consisted of types 1 and 2, with lesser amounts of type 3. Many of the types preserve faint layering parallel to the ore-body walls, produced by alternating textural variations in hematite or by interlayering of massive hematite with more porous hematite or carbonates. Texture types 4 and 5 become more abundant with depth in the Zenith mine (Machamer, 1968). These five textures record a progressive hypogene upgrade of BIF to hematite ore that is generally similar to what has been observed in recent research at the Soudan mine (Allerton, 2025; Allerton et al., 2025). Upgrade processes include initial silica replacement by massive hematite, followed by repeated brecciation and multi-stage cementation, and downward transition to carbonate assemblages, producing the dense, low-impurity ore that made the Ely deposits economically significant (Machamer, 1968). -3- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Hematite ore textures from the Sibley and Zenith mines, Ely, MN. A) Type 1 texture showing dense crystalline “matrix” with primary hematite aggregates (white to off white, Hem 1) and vug spaces (black, V). B) Type 2 texture exhibiting brecciated Type 1 material (Hem 1 fragment outlined with white dashed line) cemented by secondary hematite crystals (Hem 2) with reticulated pattern and occasional minute silicates (light gray). C) Type 3 texture displaying brecciated Type 1 material (Hem 1) cemented by mostly carbonates (patchy dark gray, Crb) and some silicates (light gray, Sil). D) Type 4 texture presenting mainly carbonates (patchy light and dark gray, Crb), sporadic silicates (light gray, Sil), and hematite aggregates (Hem 1 fragment outlined with white dashed line) and stingers. REFERENCES Allerton, Z.P., 2025. Thermal and hydrothermal effects of Proterozoic events on Archean rocks in northeastern Minnesota, USA: University of Minnesota ProQuest Dissertations & Theses [Ph.D. thesis]. Allerton, Z.P., Courtney-Davies, L., Danišík, M., Hudak, G.J., Teyssier, C., Mitchell, J.T., and Larson, P., 2025. Hematite double-dating defines Proterozoic mineralization and thermal history of Archean banded iron formations in northeastern Minnesota, USA: Geology, https://doi .org /10.1130 /G53517.1. Machamer, J. F., 1968. Geology and origin of the iron ore deposits of the Zenith Mine, Vermilion District, Minnesota (Special Publication SP-2). Minnesota Geological Survey. -4- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Decoding Shear Zone Evolution in the McFaulds Lake Greenstone Belt, Ontario: Constraints on Crystal-Plastic Deformation and Timing from in-situ Titanite U–Pb Thermochronology ANGOMBE, Moses1, PHILLIPS, Noah2, HOLLINGS, Pete1, STEPHAN, Tobias1, SHESHNEV, Vlad1, DELLER, Mathew3 and SMITH, Andrew3 1 Department of Geology, Lakehead University, 955 Oliver Rd, Thunder Bay, P7B5E1, ON, Canada Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, 90089, California, United States of America 2 3 Wyloo, 1127 Premier Way unit 1, Thunder Bay, 90089, P7B 0A3, ON, Canada Constraining deformation conditions, kinematics and timing of shear zone activity is essential for determining whether mechanical processes concentrate and localize metal deposits. The McFaulds Lake Greenstone Belt in northern Ontario hosts some of Canada’s most prospective mineralization, including magmatic sulphide, chromite and volcanogenic massive sulphide (VMS)–type deposits. A robust reconstruction of the belt’s deformation history is hindered by an understudied, poorly exposed, arcuate, regionally extensive, dextral shear system including, the Webequie, Triple‑J, and McFaulds shear zones. This study integrates field-based structural observations, microstructural analysis, and in-situ titanite U–Pb geochronology to (1) resolve the kinematic architecture of the major shear zones, (2) constrain the crystal-plastic deformation mechanisms, and (3) determine the temperature and timing of deformation. Newly acquired kinematic results derived from field outcrop‑scale S–C fabrics and asymmetrically rotated porphyroclast microstructures indicate that the NW‑striking Webequie Shear Zone accommodated dextral‑reverse displacement, while the NE‑striking McFaulds and Triple-J Shear Zone are characterized by a dextral‑normal sense of shear. Deformed quartz in phyllonites and mylonites from all shear zones exhibits fine‑grained polygonal aggregates with a few subgrains and a weak crystallographic preferred orientation. These textures indicate that shearing was accommodated predominantly through diffusion‑creep–assisted grain‑boundary sliding processes. Five deformed titanite grains from mylonitic tonalite associated with the Triple‑J shear zone yielded U–Pb dates of ~2775 Ma and Zr‑in‑titanite temperatures of 530–640 °C. In contrast, eighteen euhedral to subhedral titanite grains yield dates between ~2768 and ~2812 Ma and Zr‑in‑titanite temperatures of 650–900 °C. All analyzed titanite grains show no significant difference in temperature or U–Pb dates between rims and cores. We infer that the younger U–Pb dates (~2775 Ma) recorded in deformed titanite constrains the timing of crystal‑plastic deformation, whereas the older, higher‑temperature dates (~2768–2812 Ma) from intact titanites reflect either metamorphic or crystallization. The overlap in deformation and crystallization ages for both deformed and undeformed titanites suggests that shearing in the McFaulds Lake Greenstone Belt was broadly synchronous with emplacement of the regional tonalite suite. These preliminary results show that both shear deformation and magmatism play a critical role in forming the McFaulds Lake Greenstone Belt and its critical mineral deposits. -5- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Coeval silicate melt and PGE-bearing salt melt inclusions in the Thunder and Seagull intrusions, Ontario: An overview of evidence and data processing challenges. BAIN, Wyatt1 and HOLLINGS, Pete 2 1 2 Department of Earth Sciences, Western University, 1151 Richmond St, London, ON N6A 5B7 Canada Department of Geology, Lakehead University, 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada The Seagull (~90km north-northeast of Thunder Bay) and Thunder (~12 km north-northwest of Thunder Bay) intrusions are two magmatic sulphide-bearing mafic-to-ultramafic intrusions formed during the early stages of Midcontinent rift (MCR) formation. Investigation of olivine crystals from both intrusions reveals abundant assemblages of polycrystalline silicate inclusions and coeval assemblages of hypersaline inclusions. Both inclusion types occur along primary growth zones in their host crystals and undergo partial homogenization at >700 °C. This indicates that these inclusions contain primary, orthomagmatic fluids trapped at magmatic conditions (i.e., immiscible silicate and salt melt). Scanning electron microscope (SEM) analysis shows that the silicate melt inclusions from both intrusions have similar bulk chemistry and host assemblages of feldspar-apatite-phlogopitebiotite-ilmenite-pyrrhotite with a coexisting volatile phase. Similarly, salt melt inclusions from both intrusions also had similar bulk compositions and comprise mixtures of NaCl-KCl with variable amounts of C- and B-bearing salts. The time-resolved laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) Figure 1: a., b., Photomicrograph of olivine-hosted coeval assemblages of silicate (SMI) and salt melt (HIS) inclusions from the Thunder (a) and Seagull (b) intrusions. c. Annotated backscatter electron (BSE) image of a silicate melt inclusion exposed at the surface of an olivine crystal. Alb=Albite; Bio=Biotite; Phl=Phlogopite; Apt=Apatite; Hbl=Hornblende; Po=Pyrhotite; Ill=Illmenite; Ol=Olivene d. BSE image of a salt melt inclusion exposed at the surface of an olivine crystal and accompanying energy dispersive spectroscopy maps showing the distribution of selected elements for the same area (right). -6- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 signals from unhomogenized salt melt inclusions from both intrusions consistently showed unambiguous, overlapping peaks for the following element groups: K-P-La-Ce-Ta-U-Th-Nb-RbSr-Ba-Nd-Li, Co-Ni-Cu-Zn-Ag-Pb-S, and Pd-Pt-Au-Sb-Bi. The overlapping peaks for base metals and S likely reflect the presence of crystalline sulphides. Likewise, the overlap of the PGE+Au and Sb-Bi suggests the presence of PGE-bearing antimonide and bismuthide minerals (i.e. PGM). This indicates that salt melts coexisted with silicate melts during the emplacement of both intrusions and were significantly enriched in base metals and PGEs. This data, along with observations of salt melt inclusions in other mafic-ultramafic intrusions (Mcfall et al., 2021; 2023), suggests that these fluids may be important transport media for Ni-Cu-PGE in orthomagmatic environments. Salt melt compositions derived from LA-ICPMS data had unusually high PGE concentrations in the 10s to 100s of ppm. These results should be treated critically, as reducing data from salt melt inclusions presents several technical challenges. These include uncertainty in determining a major element internal standard for salt inclusions and matrix mismatch between the inclusions and the external standard. ICPMS systems are also typically limited in their ability to analyze halogens, C, and S, which are typically major element components of salt melt inclusions (e.g. Xu et al, 2024; Bain et al., 2022). This talk will provide an overview of the geology of the Seagull and Thunder intrusions, present textural and geochemical data from coeval polycrystalline silicate melt and salt melt inclusion in both and discuss the various data reduction schemes being used on this data set. This talk will also discuss a general workflow for salt melt analysis using SEM and LA-ICPMS techniques. REFERENCES Bain, W.M., Lecumberri-Sanchez, P., Marsh, E.E., and Steele-MacInnis, M., 2022. Fluids and melts at the magmatichydrothermal transition, recorded by unidirectional solidification textures at Saginaw Hill, Arizona, USA. Economic Geology, doi:10.5382/econgeo.4952 McFall, K.A., McDonald, I., Yudovskaya, M.A., Kinnaird, J., Hanley, J.J., Kerr, M., and Tattitch, B., 2023. Carbonatedominated hypersaline brines and their importance for metal transport in magmatic and magmatic-hydrothermal critical mineral systems. AGU Fall Meeting, San Francisco, Volume of Abstracts, V44A-08 McFall, K.A., McDonald, I., Yudovskaya, M.A., Kinnaird, J., Hanley, J.J., Kerr, M., and Tattitch, B., 2022. High temperature (> 800° C) brine and sulphide melt interaction during the formation of Northern Bushveld magmatic sulphide Cu-NiPGE deposits. Goldschmidt Conference, Hawaii, Volume of Abstracts, #9496 Xu, X., Bain, W.M., Tornos, T., Hanchar, J.M., Lamadrid, H.M., Lehman, B., Xu, X., Steadman, J.A., Bottrill, R.S., Soleymani, M., Rajabi, A., Li, P., Tan, T., Shihong Xu, S., Locock, A.J., Steele-MacInnis, M., 2024. Magnetiteapatite ores record widespread involvement of molten salts. Geology. 52, 417-422. doi:10.1130/G51887.1 . -7- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Preliminary geochronology of lithium pegmatites and host rocks, Archean Superior Province, northwestern Ontario BEYER, Steve1, CUTTS, Jamie1, HNATYSHIN, Danny1, POWELL, Jeremy1, CAMACHO, Alfredo2, CAWOOD, Tarryn3, and DREVER, Garth4 1 2 3 4 Natural Resources Canada, Geological Survey of Canada, 601 Booth Street Ottawa, ON K1A 0E8 Canada University of Manitoba, 125 Dysart Rd Winnipeg, MB R3T 2N2 Canada University of British Columbia-Okanagan, 3247 University Way Kelowna, BC V1V 1V7 Canada Frontier Lithium Inc., 2614 Belisle Drive Val Caron, ON P3N 1B3 Canada With a combined resource estimated at 50 million tonnes Li grading 1.6% Li2O [1], the PAK and Spark lithium-cesium-tantalum (LCT) pegmatites in northwestern Ontario represent a major potential source of Li, as well as other rare metals such as Nb, Sn, Ta, Rb, and Cs. Together with other Li pegmatite showings in the region (Fig. 1), this suggests high Li prospectivity for the northwestern Superior Province. Better understanding of these significant but understudied pegmatites, together with their peripheral peraluminous granites and other host rocks, will help refine models of rare-metal-enriched pegmatite formation in Archean terranes, and lead to improved discovery success. Here we present multi-mineral geochronological data for the pegmatites and host rocks to clarify connections between pegmatite emplacement and regional tectonics. The crystallization ages of pegmatites and host rocks were investigated using U and Pb isotopes in zircon and monazite measured by SHRIMP. The oldest rock in the area is gabbro that hosts the Spark pegmatite, in which zircon gives an age of 2861 ±3 Ma. Although this unit is mapped as the 2925 Ma Setting Net assemblage of the Favourable Lake greenstone belt, the age is instead within error of the younger 2858 ±5 Ma Eastern Trout assemblage [2]. Zircon in the Pakeagama Lake granite, a biotite-muscovite-garnet peraluminous granite that hosts the PAK pegmatite, gives an age of 2727 ±4 Ma, the first reported age for this pluton. Zircon from coarse K-feldspar-muscovite-apatite-quartz pegmatite at PAK, and zircon from tonalite that hosts the Pennock Lake pegmatite 20 km northwest of PAK, yield ages of 2727 ±1 and 2728 ±4 Ma, respectively, which are the same age as the Pakeagama Lake granite within error. Similar Th/U ratios, indistinguishable ages, and some textural evidence suggests that PAK pegmatite zircon may be inherited from the Pakeagama Lake granite. An overgrowth on one zircon in Spark gabbro gives an age of 2683 ±6 Ma. Isotopes of Hf are used to trace the source of the melt from which the zircon crystallized, and were measured in situ using LA-MC-ICPMS in the same location as the SHRIMP spots. Zircon from gabbro hosting the Spark pegmatite have the most radiogenic εHf values of 5.30 ±0.33, intersecting the value of depleted mantle at 2.86 Ga. Zircon from the PAK pegmatite and tonalite hosting the Pennock Lake pegmatite are less radiogenic, having εHf values of 2.21 ±0.35 and 1.25 ±0.25, respectively, possibly suggesting mixing with older continental crust. Lastly, we examine the thermochronology of muscovite in pegmatite zones, and biotite and hornblende in host rocks and contact zones using Ar-Ar isotope systematics. Step heating age spectra for muscovite (n=10) in the PAK, Spark, and Pennock pegmatites, and the Pakeagama Lake granite, are all disturbed and yield integrated ages between 2532 and 2174 Ma. Hornblende (n=1) in gabbro at Spark gives a slightly disturbed age spectrum with a pseudo-plateau age of 2805 ±4 Ma. Biotite (n=3) in metavolcanics at Spark, and at the contact between the Spark pegmatite and metavolcanics, yield pseudo-plateau ages of 2447 and 2446 ±1 Ma, respectively, whereas biotite in the Pakeagama Lake granite yields a pseudo-plateau age of 1955 ±10 Ma, possibly suggesting partial disturbance of Ar systematics during the Trans-Hudson orogeny. In situ Ar-Ar ages in transects from grain edge to center in muscovite from the Spark pegmatite range from 2687 ± 16 Ma to 1933 ±42 Ma, the oldest age indistinguishable from the U-Pb zircon overgrowth age of 2683 ±6 Ma in Spark gabbro. It is possible this age (~2685 Ma) represents the emplacement of the Spark pegmatite. Taken collectively, these data indicate that the host rocks comprise both ~2861 Ma gabbro and ~2727 Ma granite and tonalite. Although pegmatite emplacement has not yet been directly constrained, it may have occurred together with a thermal pulse at ~2685 Ma, as recorded by Ar-Ar dates from muscovite in the Spark pegmatite, -8- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 and a zircon overgrowth in the host rock. Figure 1. Map showing the location of LCT pegmatites in northwestern Ontario and their host rocks. The area shown in the main map is indicated by the red box in the location map. LCT = lithium-cesium-tantalum; NRCan MRDEM = Natural Resources Canada medium resolution digital elevation model REFERENCES Accad, E., Bisaillon, C., Gagnon, D., Ibrango, S., Liskovych, V., Prévost, G., Sellars, E., and Vasquez, L., 2025. NI 43-101 Technical Report Feasibility Study – PAK Lithium Project, Mine and Mill in Northwestern Ontario, Canada. DRA Americas Inc. Corfu, F., Davis, D.W., Stone, D., and Moore, M.L., 1998. Chronostratigraphic constraints on the genesis of Archean greenstone belts, northwestern Superior Province, Ontario, Canada. Precambrian Research, 92, 277–295. -9- �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Quartz Trace Element and TEM Analysis of Selected Economic LCT Pegmatites BILBOE, Michael1, ZUREVINSKI, Shannon1, and CONLY, Andrew1 1 Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada. This study assesses geochemical and textural trends of economic LCT-type pegmatitic quartz using different analytical applications, namely laser ablation- inductively coupled plasma mass spectrometry (LA-ICP MS) trace element geochemistry, microscope-based laser induced breakdown spectroscopy (LIBS) and high-resolution transmission electron microscopy with- energy dispersive X-ray (TEMEDX) analyses. The study utilized samples from well-documented economic LCT pegmatites (Northwestern Ontario and Manitoba) to assess a variety of modern questions relating to trace element geochemistry. Specifically, this study observes geochemical trends in trace element composition of quartz that display spodumene-quartz intergrowth (SQUI) textures, extrapolates classification of SQUI textures (after Breasley, 2025) to the economic Pakeagama pegmatite (Ontario) and utilizes HR-TEM techniques to image potential Li-bearing nano inclusions hosted within quartz. Breasley (2021) outlined varieties of SQUI originating from unique crystallization sequences. In this study, SQUI from the Pakeagama pegmatite was compared to the recent proposed classifications to ensure consistency in texture classification can be met in different pegmatite systems. Few studies have targeted quartz trace element trends in Group 1 SQUI-bearing pegmatites. Trace element trends in SQUI should be properly understood to avoid improper conclusions when inferring mineralization trends outlined by Müller et al. (2021). Trends in SQUI-associated quartz trace elements were analyzed and compared with non-SQUI pegmatite quartz trace element trends using LA-ICP-MS and LIBS. It was found that few groups of trace elements, particularly Na and Ge, show weak to moderately depleted values with respect to the ratio of Li/Al specifically in quartz grains associated with SQUI (Figure 1). This is interpreted to be the result of trace elements present in the parent mineral (petalite) preferentially incorporating into spodumene rather than quartz during SQUI formation. Additionally, LIBS analysis suggests that elevated concentrations of Li are incorporated into micas and feldspars in the North Aubry sample, likely related to elevated trace element incorporation seen in quartz. Nanoinclusions (fluid and mineral) are thought to be a major contributor to trace element incorporation in quartz (Shah et al., 2022). TEM-EDX analysis was conducted to document and image potential nanoinclusions hosted in quartz. The analyzed portion of the North Aubry sample did not host nanoinclusions displaying any detected Li signatures, however, a decrepitated nanofluid inclusion, with detected sodium and chlorine, was identified (Figure 2). The results suggest that nanoinclusions, while present, may not necessarily contribute significantly to trace element concentrations of Li, Ti, Ge or Be in pegmatitic quartz (possibly due to their presence below detection limits), however, the observed nanoinclusions could suggest the potential Li-brine fluid fluid inclusions and this may be contributing to well-documented quartz trace element concentrations in quartz. REFERENCES Breasley, C. (2021). Lithium aluminosilicate formation and textural origins in evolved pegmatites: Insights from the Tanco Pegmatite, Manitoba and Prof Pegmatite, British Columbia. Doctoral Thesis, University of British Columbia. Müller, A., Keyser, W., Simmons, W. B., Webber, K., Wise, M., Beurlen, H., Garate-Olave, I., Roda-Robles, E., & Galliski, M. Á. (2021). Quartz chemistry of granitic pegmatites: Implications for classification, genesis and exploration. Chemical Geology, 584, 120507. Shah, S. A., Shao, Y., Zhang, Y., Zhao, H., & Zhao, L. (2022). Texture and Trace Element Geochemistry of Quartz: A Review. Minerals, 12(8), 1042. Young, T. (2023). Trace Element Geochemistry of Pegmatitic Quartz from the Superior Province, ON HBSc thesis, Lakehead University. - 10 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Ge (PPM) Versus Li/Al ratios in analyzed samples. Samples Pakeagama, Tanco and Frontier are SQUI-hosted quartz analyses. Data from three additional non-SQUI samples, Seymour, Georgia and Mavis Lake, were included to better highlight the role SQUI has on quartz trace element incorporation (Seymour, Georgia and Mavis Lake data from Young, 2024). Figure 2: TEM image of a nanoinclusion in quartz, identified in the North Aubry sample. EDX mapping of the inclusion detected Na and Cl. - 11 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Improved Precision and Better Accuracy: SHRIMP-II Detrital Zircon Analysis of Samples Across the Stratigraphy of the Midcontinent Rift BLEEKER, Wouter1 and WODICKA, Natasha1 1 Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada As part of on-going research on the evolution of North America’s Midcontinent Rift (MCR), its stratigraphy, and the detailed setting of its mineral systems, we continue our efforts to improve the age constraints on key geological features of the rift. In addition to many new and improved U-Pb ages on igneous units [e.g., 1,2], we are also undertaking detrital zircon dating of key stratigraphic units across the MCR stratigraphy, from bottom to top (Fig. 1), to resolve remaining questions of depositional ages and sediment provenance. We do so by using the SHRIMP-II ionprobe at the GSC in Ottawa (Fig. 2). With typical spot sizes of ~13x16 μm, fewer corrections during data processing, no down-hole parent-daughter fractionation, and the ability to do multiple, carefully placed spots (away from cracks Figure 1: Generalized stratigraphy of the MCR. Many key ages and mineral systems are indicated. Small red squares identify our detrital samples analyzed by SHRIMP. Figure 2: The SHRIMP-II lab at the Geological Survey of Canada, Ottawa. (SHRIMP: sensitive highresolution ion microprobe.) or other complexities) on grains of particular interest, the SHRIMP-II ionprobe yields significantly more precise and accurate data than more rapid laser ablation analysis, and a more rigorous check on concordancy [3,4]. A typical sample run will analyze 80–100 grains, with >90% of the results falling within the 95–105% concordancy interval (accuracy) used in final interpretation. With multiple spots (n=3–5) on key grains, the 2s uncertainty of weighted mean ages can be improved to ±5–15 Ma (precision). All of this does take a fair amount of machine time, with a typical spot analysis taking ~15 mins, and an entire sample run, including calibration on well-characterized zircon reference materials, more than 24 hrs. Analysis is done on polished grain mounts that are imaged in both BSE (backscatter) and CL (cathodoluminescence) mode prior to analysis to guide grain selection and spot location. Here we briefly discuss some initial results. One such result, on the high-energy “event layer” near the top of the Gunflint Formation, was presented at an earlier ILSG meeting [5]. It confirmed that this layer contains ejecta material from the Sudbury target area in the form of ca. 2460–2450 Ma zircons from the Creighton Granite and Copper Cliff Rhyolite. In the next sample up (Rove Formation greywackes), our results fail to identify any age peaks younger than ca. 1845 Ma, which we consider the maximum depositional age for the Rove Formation [cf. 6], i.e. entirely a Penokean foreland basin. - 12 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 There are hints of some younger grains, perhaps to as young as ca. 1805 Ma, but this requires further work. Interestingly, in addition to some Archean input, there is also one grain at ca. 2311 Ma of the reworked felsic ash material known from the upper Huronian Supergroup [see also ref. 5]. Thin sandstone layers intercalated with the Pillar Lake Volcanics basalt flows, near Armstrong, show youngest grains at ca. 1500 Ma, similar to our Sibley Group sandstone samples, and do not contain any of the abundant younger grains (and peaks) prominent in the basal MCR sandstones discussed below (see Fig. 3). This confirms our interpretation that these thin sandstone beds and the Pillar Lake Volcanics are part of basal Sibley Group rift volcanism and sedimentation at ca. 15001480 Ma, not a northern outlier of ca. 1.11 Ga MCR stratigraphy sensu stricto [cf. 7]. Three samples of the sandstone/quartzites (Bessemer, Nopeming, and Puckwunge formations) immediately below the onset of “Early Stage” basaltic volcanism yield generally similar results with youngest grains in the 1135–1100 Ma age range (weighted means), and strong peaks (modes) at ca. 1125 Ma, 1160–1140 Ma and various older ages (e.g., 1470 Ma, Wolf River Batholith), all the way to 3.3 Ga (Fig. 3). These are just some initial results and a full and complete analysis of all 12 samples will be presented elsewhere. SOME REFERENCES [1] [2] [3] [4] [5] [6] [7] Bleeker, W., Smith, J., Hamilton, M., Kamo, S., Liikane, D., Hollings, P., Cundari, R., Easton, M., and Davis, D., 2020. Geological Survey of Canada, Open File 8722, p. 7–35. DOI: 10.4095/326880. Smith, J., Bleeker, W., and Hamilton, M., 2026. GSA Bulletin, v. 138(3–4), p. 1419–1438. DOI: 10.1130/B37649.1. Stern, R.A., 1997. Geological Survey of Canada, Current Research 1997-F, p. 1–31. DOI: 10.4095/209089. Stern, R.A., and Amelin, Y., 2003. Chemical Geology, v. 197, p. 111–146. DOI: 10.1016/S0009-2541(02)00320-0. Bleeker, W., Wodicka, N., Kamo, S., Hamilton, M., Emon, Q., and Smith, J., 2024. 70th ILSG Meeting, Proceedings & Abstracts, Part I, p. 11–12. Heaman, L., and Easton R.M., 2006. Ontario Geological Survey, Miscellaneous Release, MRD-191, 78 p. Hollings, P., Smyk, M., Bleeker, W., Hamilton, M., Cundari, R., and Easton, M., 2021. Canadian Journal of Earth Sciences, v. 58(10), p. 1116–1131. DOI: 10.1139/cjes-2021-0012. Figure 3: Example of our SHRIMP-II detrital zircon results: probability density plot for the Bessemer Quartzite (BNB-18022), sampled just below the onset of basalt flows. Inset: images of youngest grains with 3 spots (repeated analyses at the same locality), yielding a weighted mean age of 1101±14 Ma. - 13 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Update to: a complex F-rich alkalic pegmatite in the pyroxene syenites of the Stettin Complex, Wausau Complex, Marathon County, Wisconsin BUCHHOLZ, Thomas1, FALSTER, Alexander2, and SIMMONS, William2 1140 12th Street North, Wisconsin Rapids, Wisconsin 54494, 1 MP2 Research Group, Maine Mineral and Gem Museum, PO Box 500, 99 Main Street, Bethel, Maine 04217, USA 2 The Stettin Complex is the oldest (1565 +3-5 Ma, Van Wyck 1994) and most alkalic of the four intrusions that comprise the Wausau Syenite Complex, and is composed of various syenite phases. This abstract is an update to studies of this dike reported in ILSG 2024 and 2025; interested readers are referred to those abstracts. As noted by Buchholz et al. (2025) relatively common soft, pale yellow to creamy to brown grains typically contain high Ti-Ce-Fe contents with traces of other elements, and were suspected to consist of an unidentified Ti-Ce4+-Fe phase. Hand-picked grains from several visually identical samples were analyzed using powder XRD to determine crystalline phases present. Results indicate the presence of only three crystalline phases: arfvedsonite, lucasite-(Ce), (CeTi2(O,OH)6) and cerianite(Ce), (Ce4+,Th)O2. To balance charges in lucasite-(Ce), Ce is likely present as Ce4+ and OH probably absent or negligible. The altered grains may have originally been a LREE-Ti-rich mineral such as chevkinite-(Ce) or aeschynite-(Ce) that were subsequently altered under oxidizing conditions, removing LREE3+ and Si (and altering Ce3+ to Ce4+), thus allowing the crystallization of lucasite-(Ce) and cerianite-(Ce). Oxidation states appear to have fluctuated during pegmatite crystallization, as Ce3+ rich minerals such as synchysite/parisite, britholite-group minerals, monazite-(Ce) and indeed sparse remnants of chevkinite-(Ce) are present in later crystallizing portions of the dike. The potential for britholite-group minerals was discussed by Buchholz et al. (2025), and since then two group minerals have been identified: fluorbritholite-(Ce) and britholite-(Ce). Both form small pale pink to whitish rounded masses in pockets and vugs. At a minimum EDS analysis is required to distinguish these two species, as well as distinguish them from visually similar synchysite/parisite series minerals. Although bismuthinite is known from thin veinlets crosscutting the pegmatite (Buchholz et al., 2025), native Bi has subsequently been found as masses in small interior zone vugs in the pegmatite. Standards-based EDS indicates the Bi contains small amounts of Te; approximately 2-3.5 wt. %. The Te (as Te2-) is probably present as small admixed grains of a Bi-Te mineral such as tellurobismutite, hedleyite or another Bi-Te species. Possible nacareniobsite-(Y) was found as an inclusion in a small aggregate of fergusonite-(Y). Standards-based EDS data show good agreement with the published composition of the species, but the small size of the grain (approx. 25 µm) and the scarcity of the mineral suggest more examples should be sought to confirm this data. Nacareniobsite-(Y) was first described in 2023 and is so far a one-locality mineral, suggesting this may be the second locality for this species. Recent thorough cleaning of fresher exposures has revealed that parallel joints or fractures are closely spaced across much of the pit exposure. All are parallel, near-vertical and roughly oriented WNW-ESE. Possible displacement is unknown at this time, but they suggest a degree of oriented stress may have affected portions of the pluton late in its cooling history or at sometime thereafter. REFERENCES: Buchholz, Thomas, Falster, Alexander, and Simmons, Wm, 2024. Preliminary mineralogy of a pegmatite in the pyroxene syenites of the Stettin Complex, Wausau Complex, Marathon County, Wisconsin (Abstract): Institute on Lake Superior Geology, 70th Annual Meeting, Part I, Program and Abstracts, 19-20. - 14 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Buchholz, Thomas, Falster, Alexander, and Simmons, William, 2025. A complex F-rich alkalic pegmatite in the pyroxene syenites of the Stettin Complex, Wausau Complex, Marathon County, Wisconsin (abstract): Institute on Lake Superior Geology, 71st Annual Meeting, Part I, Program and Abstracts, 15-16. Van Wyck, N. 1994. The Wolf River A-type magmatic event in Wisconsin: U/Pb and Sm/Nd constraints on timing and petrogenesis (abstract): Institute on Lake Superior Geology, 40th Annual Meeting, Part 1, Program and Abstracts, 81-82. - 15 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Reassessing variations in metamorphism across the Penokean orogen in Northern Michigan: Part 2, Reinterpreting metamorphic nodes CANNON, W. F.1, SALERNO, R.1, DRENTH, Benjiman J.2 and BEDROSIAN, Paul A.2 1 2 U.S. Geological Survey, Reston, VA U.S. Geological Survey, Denver, CO A classic study of regional metamorphism (James, 1955) documented variations in metamorphic grade in Paleoproterozoic sedimentary rocks across the Upper Peninsula of Michigan. James interpreted the spatial variations of index minerals as four discrete nodes of metamorphism with concentric zones, defined in pelitic rocks, ranging from chlorite to sillimanite grade (Figure 1). Those isograds are widely used up to the present day to characterize the Penokean metamorphism of the region. These concentric nodes imply localized sources of heat across the region rather than a more widespread source related to regional orogenic processes. Figure 1. Map showing isograds interpreted by James (1955) and distribution of metamorphic index minerals from James and later studies. Compilation of metamorphic index minerals in northern Wisconsin indicates that the high-grade metamorphism extends well west of the Watersmeet node as mapped by James. Widespread garnet occurrences observed in core drilled through Paleozoic cover rocks also show that metamorphism to at least garnet grade extends far east of the exposed Peavy node. Patterned area is proposed allochthon(s) which include the Iron River-Crystal Falls and Menominee iron ranges. Gray shaded region in SE is area of Paleozoic cover. We propose an alternative interpretation for the Watersmeet and Peavy metamorphic nodes and their implied discrete heat sources. The index mineral occurrences in Figure 1 show a belt, at least 250 km long, of metamorphism to garnet or higher grade including scattered occurrences of kyanite to about 50 km north of the Niagara fault. That belt is broken by a gap of about 50 km between the Watersmeet and Peavy nodes where rocks are mostly chlorite-grade sedimentary rocks. We suggest that the gap is a result of post-metamorphic northward emplacement of allochthons of low-grade rocks over the more highly metamorphosed rocks, and that the belt of high-grade rocks is continuous beneath the allochthons. The belt of high metamorphic grade rocks, thus, is a result of regional tectonic burial to mid- to lower crustal depths, and related heating during the climactic closing phase of the Penokean orogeny, rather than to largely speculative individual heat sources. More localized - 16 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 heating by contemporaneous intrusions likely caused some magnification of regional heating such as in the Peavy node (Roy, et al., 2025) The allochthonous nature of the Paleoproterozoic rocks was first proposed by Sims (1992) and supported by more recent work (i.e. Cannon and Ottke, 1999), and recently acquired aeromagnetic and electromagnetic data. The very close spacing of isograds inferred by James (1955), such as the southeastern edge of the Watersmeet node and southwestern edge of the Peavy node, would require extreme lateral temperature gradients that are difficult to reconcile with progressive heating from a central source. Those abrupt lateral changes in metamorphic temperatures are more consistent with a tectonic contact between the high-grade rocks and overthrust low-grade rocks. If that is correct, it has significant implications for the age of allochthon emplacement and the nature of post-Penokean tectonism in the region. The peak metamorphism of the Watersmeet and Peavy nodes is well constrained to 1837-1825 Ma at depths of 30-35 km (Roy, et al., 2025: Salerno, et al., in press). Emplacement of allochthons with low metamorphic grade directly atop these mid- to lower-crustal rocks implies that the high-grade rocks were largely exhumed before emplacement, and that overthrusting must have been a post-Penokean event. Rapid exhumation of active orogens has been documented in many places globally with rates measured in kilometers/million years, so exhumation observed in Michigan could have been accomplished in 10 million years or less. Thus, the suggested overthrusting could be only slightly younger than the generally accepted ~1830 Ma date for termination of Penokean deformation, nevertheless recording continued post-Penokean regional compressive tectonism in the region. REFERENCES Cannon, W.F., and Ottke, D., 1999. Preliminary digital geologic map of the Penokean (early Proterozoic) continental margin of Northern Michigan: U.S. Geological Survey Open-File report 99-547. James, H.L., 1955. Zones of regional metamorphism in northern Michigan: Geological Society of America Bulletin, v. 66, p. 1465-1488. Roy, Supratik, Holder, R.M., Jahandar, R., Brenner, D.C., Nelson, L.L. and Viete, D.R., 2025. Mantle heating drove shortduration Barrovian-type regional metamorphism during the Penokean orogeny, Michigan (USA) Geological Society of America Bulletin, https://doi.org/10.1130/B38653.1 Salerno, R., Cannon, W.F., Thompson, J., Souders, A., Vervoort, J., and Hillenbrand, I., in press. Unraveling protracted modification of Archean and Paleoproterozoic crust in central Laurentia, Penokean orogen, with garnet and accessory mineral geochronology and microstructural analysis: Geological Society of America Bulletin. Sims, P.K., 1992. Geologic map of Precambrian rocks, southern Lake Superior region, Wisconsin and northern Michigan: U. S. Geological Survey Miscellaneous Investigations Map I-2185, scale 1:500,000. - 17 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 An introduction to the northwestern Huron Mountains of the Upper Peninsula, Michigan: field relations and preliminary structural interpretations CARLTON, Kenz M.1, TIKOFF, Basil1, and NACHLAS, William O.1 University of Wisconsin–Madison, Department of Geoscience, 1215 West Dayton Street, Madison, Wisconsin 53706, USA 1 The Huron Mountains of the Upper Peninsula, Michigan, are part of a granite-greenstone terrane and likely represent part of the southern extent of the Superior Craton. Recent field mapping and microstructural analysis indicate the existence of an amphibolite basement intruded by compositionally variable granitoids. The amphibolite basement is a banded schist with a high amphibole content that may represent a strongly metamorphosed mafic protolith. The two plutons of this site each have rapidly varying appearances and expressions of fabrics, banding that varies from non-existent to thick gneissic, and variable compositions from monzogranite to quartz-rich tonalite lithologies. The contacts between the schist and granitoid plutons of this site vary in expression over relatively short distances and, in some cases, can be traced from a planar feature into a 50+ m wide transition zone. The relation between the granitoid and the amphibolites is intrusive, as a range of sizes of amphibolite inclusions can be found within the plutons, usually near the contacts. Mafic and felsic dikes are both abundant. Ongoing work to analyze bulk and trace element geochemistry and U-Pb geochronology will constrain the timeframe of geologic events, the tectonic origin of the groundmass (i.e., which terrane, protolith), and the source of plutonism. The pervasive regional fabric displays a general northwest strike/northeast dip; however, the foliation expression in outcrop is frequently inconsistent, with tens of degrees of difference in both strike and dip possible within 30 meters or less. In general, traceable exposures of the schist-pluton contacts are parallel or subparallel to foliation. Additional structures found in outcrops include mesoand micro-scale faults and meso-scale or larger shear zone features. In thin section, microstructures indicate solid-state deformation, including myrmekite, cuspate-lobate grain boundaries, and internal grain deformation. These analyses support the model of emplacement of quartz-rich plutons into a meta-mafic basement during regional shearing, in the northwestern Huron Mountains. - 18 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Petrography and Geochemistry of the Mound Lake Pluton, Northwestern Ontario CHAISSON, Amy1, SMYK, Mark1, and ZUREVINSKI, Shannon1 1 Department of Geology, Lakehead University, 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada Mound Lake lies approximately 90 km north-northeast of Thunder Bay and 25 km northwest of Nipigon. The Mound Lake Pluton is a 7 km-wide, ovoid, muscovite-bearing granite that has intruded Quetico metasedimentary rocks. It was first described by Hart (2005) and Hart et al. (2005) and thought to be a prospective fertile granite, capable of hosting or spawning rare metal mineralization (cf. Breaks et al., 2005). This study documents the petrography, mineral chemistry, and whole-rock geochemistry of the Mound Lake granitic rocks. The study utilized samples from an initial geochemical and geological reconnaissance program (Smyk, 2022). Thirty-one samples were collected from the pluton and another was collected from from a granitic pegmatite dyke in andalusite schist from the shore of Frazer Lake. Analytical methods included transmitted light microscopy, major and trace element whole-rock geochemistry, and quantitative mineral compositional analyses using Scanning Electron Microscopy- Energy Dispersive X-ray Spectroscopy (SEM-EDX) with Back Scattered Electron (BSE) imaging to characterize mineral textures and compositions. The Mound Lake granitic rocks host irregular pegmatitic patches and miarolitic cavities containing quartz and large, drusy K-feldspar crystals. Massive, medium-grained granitic rocks are crosscut by a variety of aplitic and pegmatitic dykes. Petrographic and mineral compositional analysis identifies the pluton as a two-mica granite, composed of K-feldspar, quartz, muscovite, biotite, and plagioclase, with accessory zircon, apatite, monazite, tourmaline and thorite. Plagioclase, whose compositions range from albite to oligioclase, locally exhibited Na-rich, albite rims. Biotite compositions were found to represent annite/siderophyllite endmembers. Perthitic exsolution and granophyric intergrowths exemplify late-stage crystallization, while sericitization and chlorite alteration are related to post-magmatic hydrothermal activity. The presence of granophyric intergrowths suggests that at least some portions of the magma experienced pronounced undercooling during the final stages of crystallization. Geochemical data confirm a peraluminous, S-type affinity (Alumina Silica Index of 1.05–1.31) with trace element signatures plotting in the Volcanic Arc Granite (VAG) and syn-collisional fields. Granitic rocks display moderate LREE enrichment and HREE depletion, with variable Eu anomalies reflecting the relative role of plagioclase fractionation and accumulation. The Mound Lake Pluton shows increased Li and Cs (+ Ce, Ta and Be) concentrations along its northern contact (Figure 1). Elevated Ce concentrations correlate with samples with higher monazite content. The consistently peraluminous nature and mineralogy (muscovite + biotite, + garnet) support the contention that the pluton is a product of metasedimentary melting, likely triggered by thermal relaxation following oblique accretion in the Superior Province (Chappell, 1999). A spodumene-bearing, granitic pegmatite dyke, discovered in 2023 (https://www.geologyontario.mines.gov.on.ca/mineral-inventory/ MDI000000003501), approximately 3 km north of the northern contact of the pluton, attests to the fertility of local granitic rocks. - 19 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1. Li (left) and Cs concentrations (right) across the Mound Lake pluton (data from Smyk, 2022). REFERENCES Breaks, F. W., Selway, J. B., and Tindle, A. G. (2005). Fertile Peraluminous Granites and Related Rare-Element Pegmatites, Superior Province of Ontario. Short Course Notes, 17, pp.87–125. Chappell, B. W. (1999). Aluminium saturation in I- and S-type granites and the characterization of fractionated haplogranites. Lithos, 46(3), pp.535–551. https://doi.org/10.1016/S0024-4937(98)00086-3. Hart, T.R. 2005. Precambrian geology of the southern Black Sturgeon River and Seagull Lake area, Nipigon Embayment, northwestern Ontario; Ontario Geological Survey, Open File Report 6165, 63p. Hart, T.R., Whaley, A.G. and Pace, A. J. 2005. Precambrian Geology of the Southern Black Sturgeon River–Seagull Lake– Disraeli Lake Area, Nipigon Embayment, Northwestern Ontario; Ontario Geological Survey, Preliminary Map P.3562, scale 1:50 000. Smyk, M. C. (2022). NI 43-101 Early-Stage Exploration Property Report, Mound Lake Property, Thunder Bay District, Ontario, Canada; Technical Report, 107p. https://www.geologyontario.mines.gov.on.ca/persistentlinking?assessment=20000022160. - 20 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Digital Preservation and Enhanced Utility of Exploration Core Descriptions from the Keweenaw Copper District, Michigan: Progress toward a Map-based Web Portal DeGRAFF, James, HILTUNEN, Lindsay, LAFRENIERE, Don, LIZZADRO-McPHERSON, Dan, VYE, Erika, COWLING, Bob, BORNHORST, Theodore, J., and ROSE, William (deceased) Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 U.S.A. The Michigan copper rush starting in 1843 at Copper Harbor (Fig. 1) led to 150 years of mining that produced ~7.5 x 106 MT of copper (1), attracted ~100,000 persons from 40 countries, and profoundly influenced understanding of Lake Superior geology, advances in mining technology, and the region’s pattern of life. Companies invested significantly in trenching, coring, and mining operations that generated an enormous body of geologic information. The U.S. Geological Survey (USGS) compiled much of this information in the 1950s as bedrock geology maps with supporting cross sections and reports. Available online in digital form, these map products are derived in large part from a substantial quantity of detailed paper records that are not easily accessed, including core descriptions from exploratory holes drilled from 1899 through the 1970s. Drilling records produced after the 1950s generally have not been used in later investigations also because of difficulty of access. Paper records and microfiche that degrade with time are stored at various locations (2-4), further complicating their use. A few years ago, we began a volunteer project to identify and gather such information into a digital image repository, to extract it into tabular databases, and to explore how to make it available (5) for use by scientists, industry, land-use planners, and the general public (Fig. 2). These early efforts led to a two-year project funded by a Save America’s Treasures grant (ST-256897-OMS-24) through the National Park Service, focused on drilling records in the Michigan Figure 1: Michigan’s native copper mining district with exploratory diamond-drill holes (DDHs) coded by information that is available. TBD – to be determined; WUP – Western Upper Peninsula. Technological University Archives. The current project has three phases: 1) scan all paper records of core descriptions, drafted vertical sections, and drilling metadata; 2) convert scanned records to character data and store in files with - 21 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 tabular formats; 3) create an online, GIS-based, search tool to provide access to the materials. Phase 1 of the project, now complete, has produced scanned core logs for 801 diamond-drill holes from 64 series. After the project was terminated in April 2025 and then reinstated in June, we prioritized Phase 3 to develop the online GIS-based search and delivery tool for scanned files in case funding was lost again. Functional design work is complete and implementation is being tested. Drill hole locations for the GIS-based map were digitized from USGS maps of the Keweenaw Peninsula and supplemented with data from Michigan’s EGLE website. A drillhole attribute table contains positional data, hole direction, total depth, and drilling metadata. Phase 2 of the project is ongoing and involves extracting character data from PDF files and creating tabular data for each core description. We are investigating optical character recognition to extract character data combined with AI tools to organize the data into prescribed tabular formats. This has proven successful for high-fidelity records but requires human checking and editing to ensure the accuracy of extracted data. Less well preserved records may require humans to transcribe them and manually enter characters into the tables. Upon making these MTU records available to others in an online format, we hope to extend this work to similar records in Acknowledgements: We thank the U.S. National Park Service for the grant that makes this work possible. Casey Koch and Gwen Martin performed nearly all of the document scanning. This work is possible because of the foresight of many late geologists who gathered and preserved the original paper records. Figure 2: Potential uses of the database upon completion. the other archives. REFERENCES 1. 2. 3. 4. 5. Bornhorst, T.J. and Barron, R.J., 2011, Copper deposits of the western Upper Peninsula of Michigan, in Miller, J.D., Hudak, G.J., Wittkop, C., and McLaughlin, P.I., eds., Archean to Anthropocene: Field Guides to the Geology of the Midcontinent of North America: Geological Society of America Field Guide 24, p. 83–99, doi:10.1130/2011.0024(05). Keweenaw National Historical Park, 2016, Calumet & Hecla Records – 00019/004.02.01.03-007 Microfiche Drill Core Log Library: Calumet, Michigan, U.S. Department of the Interior, National Park Service, on microfiche (accessed August 2016). White, W.S., 1985, “Unpublished diamond drillhole core logs”: U.S. Geological Survey, Field Records Collection, Boxes 282, 287-290. Michigan Technological University Archives, 2025, Major Mining Company Collections MS-001, MS-002, MS080, MS-635: J. Robert Van Pelt and John and Ruanne Opie Library, Houghton, Michigan (accessed December 2025). DeGraff, J.M. and Rose, W.I., 2020, Digital capture and preservation of historic mining data from the Keweenaw copper district, Michigan: GSA Abstracts with Programs, v. 52, no. 5, doi: 10.1130/abs/2020NC-348035. - 22 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 A new look at the Seagull mafic-ultramafic Intrusion and potential hydrogen and helium accumulations DROST, Abraham 1 and HEGGIE, Geoff 2 1 2 Rift Minerals Inc. 1113 Jade Court, #102, Thunder Bay, Ontario P7B-6V3 Canada Pursuit Geosciences, 245 Nicholetts Road, Murillo, Ontario P0T-2G0 Canada The mafic-ultramafic Seagull intrusion located approximately 80km northeast of Thunder Bay, Ontario and forms part of the Paleoproterozoic 1.1 Ga Midcontinental Rift which extends in an arcuate shape from Iowa through Lake Superior into Michigan (Fig. 1). The intrusion was intruded into the Archean Quetico Metasedimentary Terrain and transects a portion of the Sibley Group Metasedimentary rocks. The Quetico Terrain is dominated by deep water turbidites accumulated in a forearc basin between adjacent volcanic terranes, that underwent inversion during crustal accretion. Partial melting of the Quetico Terrane at depth resulted in the generation and emplacement of S-type melts at shallower levels with both uranium occurrences and LCT pegmatites present (Fig. 2). Figure 1. Geological and geophysical interpreted extent of the 1.1 Ga Midcontinent Rift centered on Lake Superior. Distribution of major rock types shown along with location of Seagull Project (Rift Minerals) and Topaz Project (helium: Pulsar Helium) Figure 2. Geology map of the Lake Nipigon area. Archean basement terrains shown in the legend. 1.1Ga Midcontinent Rift rocks shown in purple with early olivine bearing intrusions outlined in red. Uranium occurrences identified are demarked by yellow and orange circles from Ontario OMI database. Historic exploration between 1998 and 2012 on the Seagull Intrusion included airborne and ground geophysical surveys and approximately 20,000m of diamond drilling. The geology of the Seagull intrusion is characterized by mafic-ultramafic rocks, with in-excess of 700 m of variously serpentinized olivine cumulate rocks, predominantly lherzolites and pyroxenites (Fig. 3). This exploration work identified disseminated to semi-massive sulphide mineralization containing nickel, copper and platinum group elements along parts of the intrusion’s basal contact and as reef-type mineralization. Additionally, the exploration operator at the time reported the presence of naturally occurring gases at pressure. Histoically, the intrusion was targeted for orthomagmatic mineralization, without attention being paid to the presence of gas. With the discovery of an unconventional helium reservoir within the MCR, the prospectivity of the area has pivoted, resulting in new ideas in explored areas. Serpentinization is well known as an alteration process that generates hydrogen. The presence of ubiquitous uranium and LCT pegmatite occurrences in the Archean basement metasedimentary rocks of the Quetico Terrain are a potential source of helium (Fig. 2). Lithostatic pressures, structural plumbing and concentration gradients can potentially result in downward migration of generated gases (Strauch et al, 2023). - 23 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 3. East-West cross-section through the Seagull intrusion as interpreted from diamond drilling. Modified from East West Resources (2002). Figure 4. Cross section through inversion model of the Ambient noise tomography (ANT) survey completed by Sisprobe (2024). Historical drill traces shown in white. Cross section at AZ of 027° facing NNW. In 2024, Rift Minerals completed an ambient noise tomography (ANT) survey with Sisprobe to refine the internal geometry of the Seagull intrusion and to identify subsurface velocity contrasts interpreted to reflect lithological and alteration variations. Integrated interpretation of drilling and geophysical data sets, including ANT velocity modelling, has been used by Rift to refine the interpreted geometry of the Seagull intrusion and underlying basement. The ANT velocity section (Fig. 4) is of high statistical quality and agrees well with stratigraphic variations identified in drilling. An unexplained low velocity interval within or beneath high velocity Quetico basement rocks below the Seagull Intrusion, topping at ~1250m, is being targeted for high pressure gas reservoir potential (Fig. 4). Rift Minerals and its funding partner Anteros Metals Inc. initiated a drill program in 2026 to test the deep lower velocity feature with drill hole RM26-01. The drill hole intersected disseminated to locally weakly net-textured, orthomagmatic sulphide mineralization in the basal cumulate sequence of the Seagull intrusion grading:* • 7.25 metres from 587.00 to 594.25 m grading 1.58 g/t Pt+Pd (0.72 part per million Pt and 0.86 ppm Pd), with 294 ppm copper and 2,168 ppm nickel; • 1.00 m from 606.25 to 607.25 m grading 2.27 g/t Pt+Pd (1.02 ppm Pt and 1.25 ppm Pd), with 1,660 ppm Cu and 2,080 ppm Ni. * Weighted-average results using a 0.5-gram-per-tonne-platinum-plus-palladium cut-off During the drilling of hole RM26-01 pressurized gas was encountered at a depth of approximately 877m within a narrow fault zone in the Quetico basement rocks. The 877-metre occurrence is located approximately 100m southwest from drill hole WM01-08, which reportedly encountered pressurized and flammable gas at a similar stratigraphic level when drilled in 2001. The significance, continuity and composition of the gas remain under evaluation. REFERENCES Strauch, B., Pilz, P., Zimmer, M and Hierold, J., 2023. Hydrogen Migration through natural rocks – an experimental approach. Harvard University – EGU23, the 25th EGU General Assembly, held 23-28 April, 2023 in Vienna, Austria (https://egu23.eu) - 24 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Integrated X-Ray Diffraction and Petrography Document Carbonate Mineral Heterogeneity and Hematite Mineralization in the Upper Biwabik Iron Formation, MN DUFFY, Paige1, BRENGMAN, Latisha1, and EYSTER, Athena2 Department of Earth and Environmental Sciences, University of Minnesota Duluth, Heller Hall 1114 Kirby Drive, Duluth, MN 55812, USA 1 Department of Earth and Climate Sciences, Tufts University, Lane Hall, 2 North Hill Road, Medford, MA 02155, USA 2 Core LWD-99-1 preserves the ~1.9 Ga Biwabik Iron Formation located near the Virginia horn, outside the contact metamorphic aureole associated with the intrusion of the Duluth Complex ca. 1.1 Ga. In this study, X-ray diffraction (XRD) and petrographic data are used to: (1) characterize carbonate mineral heterogeneity; and (2) evaluate depositional and post-depositional mineral assemblages. Emphasis was placed on identification of Fe2+ bearing carbonates (e.g., ankerite, siderite) and hematite-magnetite relationships. To minimize contamination and weathering effects, outer surfaces were removed during processing, and veins were avoided. Samples were cut, dried, then crushed to a uniform powder using a SPEX ShatterBox. XRD analyses were performed using a PANalytical X’Pert diffractometer, with data collected in θ-2θ geometry over a range of 5-65 degrees, sufficient to capture all minerals of interest. Analysis of diffraction data was done using X’Pert HighScore (Malvern PANanalytical) software. XRD analysis of 24 samples documents the presence of multiple different carbonate and oxide minerals throughout core LWD-99-1. Carbon was detected in 92% of analyzed samples, with 77% associated with carbonate minerals. All carbonate phases identified petrographically and with scanning electron microscopy (Duncanson et al., 2024) were also detected by XRD, indicating strong agreement between methods. Siderite is the most common carbonate phase, occurring in 41.7% of samples, followed by ankerite at 33.3%, dolomite in 20.8%, kutnohorite in 16.7%, and calcite in 6.3%. Carbonate mineral distribution greatly varies by informal stratigraphic unit. Siderite is prevalent in the Lower Slaty, Lower Cherty, and Upper Slaty, whereas kutnohorite (a calcium manganese carbonate) only occurs in the Upper Cherty. Calcite is restricted to the uppermost part of the Upper Slaty while dolomite and ankerite are most abundant in the Upper Cherty but also appear once in the Lower Cherty and twice in the Upper Slaty. Overall, carbonates are more abundant in the Upper Slaty and Upper Cherty compared to the Lower Slaty and Lower Cherty. Within the Upper Slaty, siderite occurs in 42.9% of samples, ankerite in 28.9%, dolomite in 28.6%, and calcite in 14.3%. In the Upper Cherty, siderite and ankerite each occur in 50% of the samples, dolomite in 20%, and kutnohorite in 40%. These distributions highlight a clear variation of carbonate minerals in the upper portions of the stratigraphy. Additionally, preliminary XRD and petrographic observations of iron oxide minerals suggest an overall increase in hematite occurrence in the Upper Cherty and the Lower Cherty, with petrographic data indicating magnetite is more prevalent in slaty units. Such transitions towards increasing carbonate mineral diversity and increasing hematite up section could link to depositional changes in the system or post-depositional oxidation reactions. Post-depositional mineral reactions and accounting of ferrous: ferric iron ratios are of critical interest as they preserve a record of fluid: rock interaction driven by multiple geologic events. Some redox reactions that involve siderite and magnetite are of broader interest for tracking hydrogen production or stimulation potential (Geymond et al., 2023; 2025). Ongoing work includes detailed accounting and mapping of mineral distributions and mineral reactions across the lateral extent of the iron formation. - 25 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: XRD analysis of LWD-99-01 Sample MIR 17-11 taken from the Upper Cherty showing variation in carbonate mineralogy (ankerite (00-033-0282), dolomite (00-036-0426), kutnohorite (00-043-0695), and siderite (00-029-0696)). REFERENCES Duncanson, S., Brengman, L., Johnson, J., Eyster, A., Fournelle, J., Moy, A., 2024. Reconstructing diagenetic mineral reactions from silicified horizons of the Paleoproterozoic Biwabik Iron Formation, Minnesota. American Mineralogist, 109, 339-358. Geymond, U., Briolet, T,. Combaudon, V., Sissmann, O., Martinez, I., Duttine, M., Moretti, I., 2023. Reassessing the role of magnetite during natural hydrogen generation. Front. Earth Sci. 11, 1169356. Geymond, U., Truche, L., Sissmann, O., Kubaniova, D., Recham, N., Martinez, I., 2025. Mineralogical changes and H2 generation yield during hydrothermal alteration of a magnetite-siderite assemblage. Journal of Geophysical Research: Solid Earth, 130, 8. - 26 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 The Badgerow complex, a Midcontinent Rift-related REE-Zr-rich peralkaline intrusion in the Grenville Province near Verner, Ontario EASTON, Robert Michael1 and KAMO, Sandra L.2 Earth Resources and Geoscience Mapping Section, Ontario Geological Survey, retired, 933 Ramsey Lake Road, Sudbury, Ontario P3E 4W1 1 Jack Satterly Geochronology Laboratory, Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1 2 The Badgerow complex (Lumbers 1975; Easton 2025) is located approximately 8.5 km north of the community of Verner within the northern Nepewassi domain of the Grenville Province (Easton 1992). The main part of the complex is roughly circular, approximately 4.5 by 3.5 km in size (Figure 1), and is only weakly deformed, with a narrow gneissic margin and a massive to slightly foliated interior. It consists predominantly of pink weathering, medium-grained monzogranite with less than 5% mafic minerals (sample 24RME-3047). Near the eastern margin of the complex, fine-grained monzogranite veins crosscut medium-grained gabbro of the complex containing relict pyroxene cores rimmed by amphibole. The monzogranite was sampled for geochemistry and U-Pb geochronology because of the relatively undeformed nature of these rocks, and the fact that the complex is the only near-circular pluton within Nepewassi domain. Approximately 600 m northeast of the near-circular body, Lumbers (1975) included an approximately 6 km long, up to 1 km wide, lens of gneissic syenite as part of the Badgerow complex. Well-exposed along Highway 575 (Figure 1), the lens is a homogeneous, medium-grained, gneissic amphibole syenite (sample 24RME-3052) hosted by migmatites. Given its mineralogy, and its greater degree of deformation, the lens was assumed to be older than the granitic rocks. It is unclear why Lumbers (1975) included it in the Badgerow complex. Preliminary geochemical results from the complex were reported in Easton (2025, 2026). Sample 24RME-3052 (Figure 2) is peralkaline and has niobium, yttrium, zirconium and total rare earth Figure 1. Simplified geological map of the Badgerow complex in the Grenville Province north of Verner (from Easton 2025). Sites sampled for geochemistry and for U/ Pb geochronology are indicated. Figure 2. Chondrite-normalized rare earth element plot for granitoid samples mentioned in the text (from Easton 2025). Remember the y-axis scale is logarithmic, so the difference between samples 24RME-3047 and 24RME-3052 is larger than it might appear (e.g., La normalized is 97 ppm for sample 24RME-3047 but 1866 ppm for sample 24RME-3052). Sample 24RME-1114 is an undeformed monzogranite exposed near Noelville. Normalizing values of Sun and McDonough (1989) were used. - 27 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 contents (164, 155, 4800 and 1936 ppm, respectively) that are some of the highest recorded for any igneous rock sample from the Grenville Province of Ontario. There are some similarities between sample 24RME-3052 and the West Bay migmatitic monzonite body to the south of Verner (Easton 2014). Key differences are that the West Bay body samples do not show a europium anomaly (Figure 2) nor are they peralkaline. It is unclear if the gneissic syenite was originally an intrusive or a volcanic rock. If volcanic, it has a comendite composition. In contrast, granite sample 24RME-3047 has a much lower total rare earth content (Figure 2). Preliminary U–Pb chemically abraded-isotope dilution thermal ionization mass spectrometric results on zircons have been obtained from samples 24RME-3047 and 24RME-3052. Zircons from sample 24RME-3047 are discordant and lie along a reference line anchored between 1097 and 2700 Ma. The most concordant zircon from sample 24RME-3052 gives a 207Pb/206Pb age of 1106 Ma (igneous based on Th/U). This age is older than Grenvillian metamorphism in Nepewassi domain (1030-980 Ma, Easton 2026), but similar to the Early Stage of Midcontinent Rift magmatism (11101104 Ma, Smith et al. 2026) and the Rb-Sr age of a mantle-xenolith bearing lamprophyric breccia at Elliot Lake (1112.8±4.95 Ma, Legros et al. 2024). Both these potential Midcontinent Rift-related intrusions lie along the northwest-southeast rifting trend of the Early Stage of magmatism, despite their location east of any previously described Midcontinent Rift magmatism. These new results suggest that other Midcontinent Rift-related intrusions may be present in the Sault Ste-Marie to North Bay area. REFERENCES Easton, R.M. 1992. The Grenville Province; Chapter 19 in Geology of Ontario, Ontario Geological Survey, Special Volume 4, Part 2, p.713-904. ——— 2014. Geology and mineral potential of the Nepewassi domain, Central Gneiss Belt, Grenville Province; in Summary of Field Work and Other Activities, 2014; Ontario Geological Survey, Open File Report 6300, p.16-1 to 16-12. ——— 2025. Zirconium and rare-earth element potential of a Grenville Province gneiss north of Verner, northeastern Ontario; in Summary of Field Work and Other Activities, 2025; Ontario Geological Survey, Open File Report 6421, p.10-1 to 10-7. ——— 2026. Geological, geochemical, geophysical and petrographic data from the Wanup area, Grenville Province, northeastern Ontario; Ontario Geological Survey, Miscellaneous Release—Data 397. Legros, H., Czas, J., Luo, Y., Woodland, S., Sarkar, C., Shirey, S.B., Schulze, D, and Pearson, D.G. 2024. Post‑Archean Nb‑REE‑U enrichment in the Superior craton recorded in metasomatised mantle rocks erupted in the 1.1 Ga Midcontinental Rift event; Mineralium Deposita, v.59, p.373-396. Lumbers, S.B. 1975. Burwash area, districts of Nipissing, Parry Sound and Sudbury; Ontario Department of Mines, Geological Report 116, 158p. Accompanied by Map 2271, scale 1:126 720. Smith, J.W., Bleeker, W. and Hamilton, M. 2026. The 1093 Ma Crystal Lake Intrusion: A nickel-copper mineralized intrusion emplaced during the younger southwest–northeast rift phase of the Midcontinent Rift (North America); Geological Society of America, Bulletin, published online Oct 15, 2025, 20p. Sun, S-S. and McDonough, W-F. 1989. Chemical and isotopic systematics of oceanic basalts: Implications for mantle compositions and processes; in Geological Society of London, Special Publication No.42, p.313-345. - 28 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Comparing mineralogy along a surface to depth transect of the ~2.7 Ga North Limb Soudan Iron Formation, NE Minnesota. ELLISON, Kimberly1, CISNEROS, John Alex1, EYSTER, Athena2, and BRENGMAN, Latisha1 Department of Earth and Environmental Sciences, University of Minnesota Duluth, Heller Hall, 1114 Kirby Drive, Duluth, MN 55812, USA 1 Department of Earth and Climate Sciences, Tufts University, Lane Hall, 2 North Hill Road, Medford, MA 02155, USA 2 The Lake Vermilion-Soudan Underground Mine State Park in Northeast Minnesota is home to the classic 2.7 Ga Algoma-type Banded Iron Formation - a type of authigenic, chemical sedimentary rock known to record past ocean chemistry. Here, we compare multiple generations of mineralization in the Soudan Iron formation to evaluate the relative timing of oxidation reactions. Recent U-Pb and (U-Th)/He hematite geochronology places new age constraints on iron mineralization of microplaty hematite, documenting that this generation of hematite post-dates initial deposition by over 1 billion years (Allerton et al., 2025). Distinguishing between initial mineral formation and later overprinting is critical for reconstructing paleowater-rock interactions within the Soudan system. The goal of this work is to compare drill core and outcrop records from the north limb of the Soudan fold to samples from the mineralized portion of the Soudan mine, with a focus on building a spatial map documenting these oxidation reactions. To evaluate mineral reactions in the Soudan Iron formation, we combine transmitted and reflected light petrography with X-Ray Diffraction (XRD), focusing on a vertical transect of samples from drill core 26501 from the north limb of the Soudan Iron Formation, comparing these samples to nearby surface outcrop samples, and mine samples from the fold hinge to the west. Preliminary results indicate shallow core samples (28.5 to 95 feet) contain dominant mineral assemblages of quartz, calcite, magnetite, hematite, and minimal iron silicates, while deeper samples (129 to 394 feet) mainly contain quartz, magnetite, carbonate, chalcopyrite, and iron silicate assemblages, lacking visible hematite. To compare optical data to XRD data, we prepared powdered whole rock samples using standard cutting and crushing techniques for XRD scanning at positions ranging from 2θ = 5° to 2θ = 65°. Resulting peaks were matched to mineral reference patterns provided by the X’Pert HighScore analysis software and compared to observed mineralogy of thin section samples from drill core 26501. XRD results confirm the presence of quartz, magnetite, and hematite in shallow drill core samples, and an assemblage of quartz, magnetite, and iron silicates in deeper drill core samples. Combined, petrographic data and XRD data indicate hematite is confined to shallow drill core samples. This observed trend continues in petrographic data from surface outcrop samples near the same location, which also contain abundant hematite. The absence of hematite at depth in drill core samples, combined with the top-down nature of the hematite distribution, could indicate minor amounts of hematite locally formed from surface oxidation distal to the mine site. Next steps include more detailed paragenesis work in combination with larger-scale mapping of the spatial distribution of hematite in drill core along the north limb of the Soudan iron formation towards the historic mine site which sits at the fold hinge. Mapping the extent of multiple generations of oxidation reactions can help document past fluid-rock interactions and allows for identification of preserved ferrous iron-containing assemblages at depth in the iron formation. Such ferrous-iron-containing phases may record depositional information and are of interest for potential natural or stimulated hydrogen generation. - 29 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1.) Petrographic photomicrographs and X-ray Diffraction patterns of the Soudan iron formation from core 26501. (A) Reflected light image of sample 26501-28.5, a shallow (28 feet depth) banded iron formation sample with quartz and hematite. (B) Cross-polarized light image of sample 26501-191, a deeper iron formation sample (191 feet), that contains quartz, calcite, magnetite, and iron-silicate mineral phases. (C) XRD analysis of sample 26501-28.5 (28 feet depth) with peaks that match mineral reference patterns of quartz, magnetite, and hematite. (D) XRD analysis of sample 26501-242 (242 feet depth) with peaks that match mineral reference patterns of quartz, magnetite, and iron silicates. REFERENCES Duncanson, S., Brengman, L., Johnson, J., Eyster, A., Fournelle, J., Moy, A., 2024. “Reconstructing diagenetic mineral reactions from silicified horizons of the Paleoproterozoic Biwabik Iron Formation, Minnesota”. Mineralogical Society of America, Volume 109, Number 2, American Mineralogist, https://doi.org/10.2138/am-2022-8776. Geymond, Ugo, Briolet, T., Combaudon, V., Sissmann, O., Martinez, I., Duttine, M., Moretti, I., 2023. “Reassessing the Role of Magnetite during Natural Hydrogen Generation”. Frontiers in Earth Science, Volume 11, Frontiers, 10.3389/ feart.2023.1169356. Zsuzanna, P. Allerton, Courtney-Davies, L., Danisik, M., Hudak, G., Teyssier, C., Mitchell, J., Larson, P., 2025. “Hematite double-dating defines Proterozoic mineralization and thermal history of Archean banded iron formations in Northeastern Minnesota, USA”. Geology, Volume 53, page 11, Geological Society of America, https://doi. org/10.1130/G53517.1. - 30 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Middle school virtual field trip lessons materials for Archean formations of Lake VermilionSoudan Underground Mine State Park ERICKSON, Stephanie S.1, FAYON, Annia2 , ALLERTON, Zsuzsanna1,2, and HUDAK, George2,3,4 1 2 3 4 Curriculum and Instruction, University of Minnesota School of Earth and Environmental Science, University of Minnesota, Minneapolis, MN 55455, USA School of Earth and Environmental Science, University of Minnesota, Duluth, MN 55812, USA George Hudak Geosciences P.L.L.C., Duluth, MN 55804, USA The Lake Vermilion-Soudan Underground Mine State Park located in St. Louis County, Minnesota provides unique opportunities to learn about Archean geology and mineral resources of northern Minnesota. Archean rocks exposed in the park consist of a series of mafic lava flows and intrusive rocks interlayered with classic banded iron formation, iron ore, felsic tuffs, and chloritesericite schists (Hudak et al., 2014, Hudak and Peterson, 2014; Peterson et al., 2016) and record deformation associated with the accretionary growth of the Superior craton. A cross-section through the stratigraphy can be observed along a trail through part of the east side of the park. The trail is in the planning stages and is in collaboration with the state park. The purpose of this project is to enhance formal and informal Earth science education in Minnesota. After consultation with local secondary teachers the project expanded to include a virtual field trip with an accompanying lesson as part of the formal education portion of the project. In 2019 Minnesota revised their science standards (Minnesota Department of Education, 2019). These changes marked a significant change in the pedagogical practices aligned with national trends such as Next Generation Science Standards (NGGS) (NGSS Lead States, 2013). There are a number of shifts in instruction teachers are challenged to make when implementing these standards including using phenomenon based instruction (BSCS Science Learning, 2017; Reiser et al., 2021). Phenomenon based instruction engages students in a series of lessons arranged in a cohort storyline around a real world, observable events. An additional challenge facing Minnesota educators was moving Earth science in from 8th grade to 6th grade. According to survey data collected from the Minnesota Earth Science Teachers Association many 6th grade teachers did not feel prepared to teach Earth science content. A combination of lack of high quality instructional materials for Minnesota phenomenon and gaps in the required background knowledge are some factors contributing to these findings. This project provided teachers with high quality instructional materials that are aligned with the 2019 Minnesota State Science Standards for 6th grade teachers. Three, 45-minute lessons were designed to address the stratigraphy standard. The goal for the students is to tell the geological story of the park. The first lessons take students on a virtual walk through the park stopping at six significant outcrops along the way (Figure 1). At each stop students are making observations of the rock outcrops and hand samples while also asking questions. The second lesson, using information about rock formation, processes the map and picture of core samples taken from locations in the park (Figure 2) while applying principles of deformation and stratigraphy. formations and thus the early geologic history of the Earth. The lessons conclude with students writing a story of the Archean formations and thus the early geologic history of the Earth. - 31 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: The first two stops orient students to the park and where they learn about the park’s iron mining history including an open pit and a trip down to a deep mine. After emerging from the underground mine they make three stops at outcrops: the classic BIF outcrop, the schist in BIF outcrop, and Ely Greenstone pillow basalts. The final stop is to make observations of tuff and the lower section of the Ely greenstone from rocks found on the “ground.” (after Peterson et al., 2016 ) Figure 2: Virtual core samples that students use to correlate and deduce the order the rocks are formed in. Each core sample comes from a point of the map in figure 1. These are not actual core samples rather simplified samples that allow students to correlate the stratigraphy of the area. REFERENCES BSCS Science Learning. (2017). Guidelines for Assessing Instructional Materials that Exemplify the NGSS. https://bscs.org/ reports/guidelines-for-assessing-instructional-materials-that-exemplify-the-ngss/ Hudak, G. J., and Peterson, D. M., 2014, Non-Ferrous Mineralization Associated with the Wawa-Abitibi Terrane and Duluth Complex Cu-Ni-PGM Deposits, Northeastern Minnesota: Society of Economic Geologists, Guidebook Series, v. 47, 150 p. Hudak, G. J., Radakovich, A., Pignotta, G., and Schwierske, K., 2014, Field Trip 2 – A Walk in the Park – Neoarchean Geology of Lake Vermilion State Park: Institute on Lake Superior Geology, Proceedings Volume 60, Part 2 – Field Trip Guidebook, p. 37-75. Minnesota Department of Education. (2019). 2019 Minnesota Academic Standards in Science. https:// education.mn.gov/mdeprod/idcplg?IdcService=GET_FILE&dDocName=MDE086711 &RevisionSelectionMethod=latestReleased&Rendition=primary NGSS Lead States. (2013). Next generation science standards: For states, by state. The National Academies Press. Washington D.C. Peterson, D.M., Hudak, G.J., Radakovich, A., Pignotta, G., and Schwierske, K., 2016, Geologic Map of Lake Vermilion/ Soudan Underground Mine State Park: Precambrian Research Center Map PRC/Map-2016-01, 1:10,000 scale. Reiser, B. J., Novak, M., McGill, T. A. W., & Penuel, W. R. (2021). Storyline units: An instructional model to support coherence from the students’ perspective. Journal of Science Teacher Education, 32(7), 805–829. https://doi.org/10 .1080/1046560X.2021.1884784 - 32 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Geochemical Constraints on Mn Cycling in the Paleoproterozoic Gunflint Formation GILBERG, Nolan1, FRALICK, Philip1, and LI, Zhiquan1 1 Department of Geology, Lakehead University, 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada Iron formations (IFs) are iron-rich (>15% Fe) and siliceous (>20 wt.% SiO2) chemical sedimentary rocks that precipitated from seawater. Most IFs were deposited between 2.80 and 1.85 Ga during the Neoarchean and Paleoproterozoic, followed by a near one-billion-year hiatus before reappearing in the Neoproterozoic. The Gunflint Formation in the Animikie Basin, overlain by the siliciclastic Rove Formation, is composed mainly of IFs, chert, carbonates, and minor siliciclastic sediments deposited during the Paleoproterozoic (~1.88 Ga), and represents the final major episode of IF deposition. Therefore, investigating the source materials and redox conditions of the Gunflint Formation is key to understanding this transitional period in the marine environment. This study conducts a high-resolution stratigraphy and chemostratigraphy study of a 142.9-meterdeep drill hole (MC-1-89), located south of Thunder Bay in the Gunflint Iron Range. Samples were taken in short intervals of ~1-5 meters along the drill core, where 55 samples were analyzed for major, trace and rare earth (REE+Y) element concentrations through ICP-OES and MS. All samples from drill core MC-1-89 consists of IFs (often magnetite, hematite rich, or jaspilite), chert, carbonates, and siliciclastic rocks (often fine sandstone and argillaceous mudstone). IFs contain a total Fe content ranging from 15-36%. MnO values are enriched in the upper and lower portion of the hole (0.30, 0.57 wt.% respectively), while depths 30-90m show an average of 0.10 wt.%. Samples with >1 wt.% Al2O3 and >0.1 wt.% TiO2 are excluded for REE+Y analysis due to potential detrital contamination. The rest of the samples do not show correlation of REE+Y with Al2O3 + TiO2 (R2 < 0.1), suggesting the REE+Y system is authigenic. All samples display positive Eu/Eu* (1.18 – 3.14, average ~1.83), suggesting a strong hydrothermal input. Moreover, most of the samples display a depletion of LREE, enrichment of HREE, along with high Y/Ho ratios (average of 30.4), suggesting marine signatures. All these features are typical of global Paleoproterozoic IFs. A key distinction between the Gunflint Formation and other Paleoproterozoic IFs is the presence of positive Ce anomalies in many samples, which contrasts with most Archean and Paleoproterozoic IFs. Ce/Ce* values decline with depth (0.35 – 1.92, average =1.32). The elevated Ce might be related to the cycling of Mn oxides in the water column, but further detailed work is still needed to better constrain the mechanism. - 33 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Modified Sequential Iron Extraction Method for Analyzing Rare Earth Elements in Banded Iron Formations GOSAI, Meghna, FRALICK, Philip, and LI, Zhiquan Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1 Canada Banded iron formations (BIFs) are chemically precipitated sedimentary rocks characterized by alternating iron-rich and silica-rich layers, formed predominantly in Precambrian marine environments. Rare earth elements (REEs) are among the most used geochemical tools for understanding the origin and deposition of iron formations and other iron oxide–rich sedimentary rocks, because the precipitation of ferric iron oxyhydroxides can adsorb signatures from the water column and thus preserve a seawater REE signature. However, BIFs that formed in shallow-marine settings often contain detrital material, thereby affecting the bulk rock geochemistry. For instance, detrital input may elevate light REEs and suppress yttrium (Y) anomalies, complicating interpretation. Sequential extraction of different iron phases (e.g., magnetite, iron carbonates, and iron sulphides), developed by Poulton and Canfield (2004), was used to accurately determine the composition of ironbearing minerals without interference from detrital materials. However, the chemical solutions used in this process introduce additional dissolved ions, thereby increasing total dissolved solids (TDS) and making it difficult to analyze low REE concentrations using ICP-MS. Therefore, this study aims to develop a method to reduce the introduced TDS while still extracting enough REEs for detection by ICP-MS. Six concentrations (10%, 20%, 40%, 60%, 80%, and 100%) of an ammonium oxalate monohydrate and oxalic acid solution were used for sequential extraction. This solution was used to selectively extract magnetite from two types of samples: (1) magnetically selected magnetite grains, and (2) bulk rock powder from the same sample. The extracted iron solutions were then analyzed for REE anomalies for interpretation. Sample patterns were compared to determine the minimum concentration required to introduce additional elements into the solution without resulting in a high dilution factor. The patterns were also compared with those from Dolega’s (2018) bulk-rock acid digestion to assess any improvements in REE patterns. The results and comparison indicate that the REE patterns show the greatest improvement at a solution concentration of 40%. However, one concern is the absence of a positive Y anomaly, which differs from the original bulk rock data (Dolega, 2018). It is likely that reprecipitation causes the interference with Y, but further work is still needed for this investigation. REFERENCES Dolega, S., 2018. Geochemistry of Shallow and Deep Water Archean Meta-Iron Formations and Their Post-depositional Alteration in Western Superior Province, Canada. Unpbl. MSc thesis, Lakehead University, Department of Geology. Poulton, S.W., and Canfield, D.E., 2005. Development of a Sequential Extraction Procedure for Iron: Implications for Iron Partitioning in Continentally Derived Particulates. Chemical Geology, 214, 209–221. - 34 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Time-to-depth conversion of seismic-reflection data from eastern Lake Superior and implications for the eastern arm of the Midcontinent Rift GRAUCH, V.J.S.1, and HELLER, Samuel J.2 1 2 U.S. Geological Survey, MS 973, Federal Center, Denver, CO 80225 U.S. Geological Survey, MS 939, Federal Center, Denver, CO 80225 Seismic-reflection data were acquired in the mid 1980s along several lines across eastern Lake Superior by industry and the Great Lakes International Multidisciplinary Program on Crustal Evolution (GLIMPCE) (Fig. 1). The lines form part of a larger network of crossing lines over the entire lake, which can be used to develop three-dimensional geologic models of the Mesoproterozoic Midcontinent Rift that lies below. To better interpret these lines, we developed velocity models to convert seismic reflections versus two-way travel time (TWTT) to reflections versus depth. In addition, the velocity models themselves provide insights into the structure of the Midcontinent Rift by recognizing common velocity ranges for certain rock types (Grauch, 2023). Figure 1. Seismic-reflection lines overlain on Bouguer gravity for eastern Lake Superior. Gravity map from Anderson and Grauch (2018) is displayed in color shaded-relief, with illumination from the northeast. Lake Superior shores are outlined in black. Digital data are publicly available for lines A, F, and G, collected as part of GLIMPCE. Digital data were derived for the industry lines (LS-15, LS-25, LS-26, and LS-36) by scanning published images from McGinnis and Mudrey (2003) and estimating the location parameters. Velocity model development was guided by (1) bathymetric data, providing thickness of the lowvelocity water column; (2) previous shallow seismic-reflection studies targeting the top of bedrock below glacial till and lake sediments; (3) previous refraction studies, which provide information on depth and compressional velocity at interfaces of large velocity contrast; and (4) correlations across multiple lines, allowing independent constraints on individual lines to influence modeling on crossing lines. In addition, digital data for the GLIMPCE lines were analyzed using common midpoint gathers to check the accuracy of the modeled velocities. Gravity anomalies provided qualitative guidance on broad velocity variations. The velocity models consist of intervals of constant velocity bounded by prominent horizons recognized in the seismic-reflection TWTT sections before time-to-depth conversion. After - 35 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 conversion, the resulting reflection sections versus depth show similar overall geometry compared to the TWTT sections, although structural relief is more subdued. Thus, several qualitative aspects of the results are similar to those observed by previous workers (e.g., Cannon et al., 1989; Mariano and Hinze, 1994; Samson and West, 1994). For example, lines that cross the lake from SW to NE are interpreted to show a symmetric basin of fairly uniform basalt thickness except at the edges of the basin, where the basalts rise and thin and are expressed by pronounced gravity highs (Fig. 1). The thickness of the overlying sedimentary section increases toward the middle of the basin to 7–9 km and the underlying volcanic section is locally folded. In contrast, the velocities derived from the modeling indicate different rock types than anticipated from the previous interpretations at the edges of the basin. The upturned basalt edges have been previously interpreted as basalt layers thrust over the younger Jacobsville Sandstone, with sharply rounded reflection patterns considered as thrust rollovers on lines LS-26 and LS-36 between the crossings with LS-15 and LS-25 (Mariano and Hinze, 1994). Where these authors interpret Jacobsville Sandstone under thrust faults, the models indicate velocities on the order of 6.0 km/s instead of the expected velocity range of 3.0–4.5 km/s for this unit (Grauch, 2023). The higher velocities are consistent with those of igneous or basement rocks instead. An alternate interpretation is that the upturned edges represent the vestiges of magmatic feeder zones and the sharply rounded reflection patterns represent igneous intrusions. The zones may be faulted and folded due to the later compressional regime that affected the region. REFERENCES Anderson, E.D., and Grauch, V.J.S., 2018, Updated aeromagnetic and gravity anomaly compilations and elevationbathymetry models over Lake Superior: U.S. Geological Survey data release, https://doi.org/10.5066/F7F18X8S. Cannon, W.F., Green, A.C., Hutchinson, D.R., Lee, M.W., Milkereit, B., Behrendt, J.C., Halls, H.C., Green, J.C., Dickas, A.B., Morey, G.B., Sutcliffe, R.H., and Spencer, C., 1989, The North American Midcontinent rift beneath Lake Superior from GLIMPCE seismic reflection profiling: Tectonics, v. 8, p. 305–332. doi: 10.1029/TC008i002p00305. Grauch, V.J.S., 2023, Compressional-wave seismic velocity, bulk density, and their empirical relations for geophysical modeling of the Midcontinent Rift system in the Lake Superior region: U.S. Geological Survey Scientific Investigations Report 2023-5061, 60 p. https://doi.org/10.3133/sir20235061. Mariano, J., and Hinze, W. J., 1994, Structural interpretation of the Midcontinent Rift in eastern Lake Superior from seismic reflection and potential-field studies: Canadian Journal of Earth Sciences, v. 30, p. 619–628. McGinnis, L.D., and Mudrey, M.G., Jr., 2003, Seismic reflection profiling and tectonic evolution of the Midcontinent rift in Lake Superior: Wisconsin Geological and Natural History Survey MP 91-2. https://wgnhs.wisc.edu/pubs/000480/. Samson, C., and West, G. F., 1994, Detailed basin structure and tectonic evolution of the Midcontinent Rift System in eastern Lake Superior from reprocessing of GLIMPCE deep reflection seismic data: Canadian Journal of Earth Sciences, v. 31, p. 629–639. - 36 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Ice flow history, surficial geology, and till composition of Georgia Lake area, northwestern Ontario HAGEDORN, Grant1 Ontario Geological Survey, Ministry of Energy and Mines, 933 Ramsey Lake Road, Sudbury, ON P3E 6B5 Canada 1 During the last glaciation, the Lake Superior basin was covered by the Laurentide Ice Sheet. The ice sheet advanced over the landscape, eroding the substrate and depositing a variety of sediments including till (a common sample medium for mineral exploration) and glaciofluvial sand and gravel (a common source of aggregates). During deglaciation, glacial lakes inundated the landscape depositing successions of silt and clay, which can act as a barrier for mineral exploration and infrastructure development. As such, the Ontario Geological Survey completed a three-year field mapping program which measured striations and landforms to decipher different ice flow directions, mapped the surficial geology around the Georgia lake pegmatite, and collected regional scale till samples to identify mineral prospectivity (Figure 1). These data hold broad applications for regional mineral exploration and land use planning / resource management decisions for local communities. Striation and landform mapping were used to determine the relative age and direction of ice flow over the region. A southwest flow is pervasive across mafic uplands, suggesting this was the paleoflow direction during thickest ice cover (Arrows labeled 1 in Figure 1). As the ice sheet thinned, it became more topographically-controlled resulting in southward ice flow in lowlands, and westward ice flow on mafic uplands (Arrows labeled 2 in Figure 1). Finally, a late-stage re-advance out of the Lake Superior basin created northwestward striations and landforms in the areas around Thunder Bay (Arrows labeled 2 in Figure 1). Surficial mapping completed in the Georgia Lake area indicate more sediment than previously identified although the sediments are mostly thin (>2 m). Till is common at surface and many new small eskers have been mapped. Glacial lake sediments are present, and at a higher elevation than previously indicated. Postglacial organic accumulations are also abundant over the landscape, specifically over poorly-drained substrates like till and glaciolacustrine silt and clay. Till samples were also collected as part of the project and analyzed for till matrix geochemistry and indicator minerals. Till compositions indicate two units differentiated based on bedrock provenance. One till contains southwest transported carbonate material while the other contains locally sourced bedrock material. Lithium material transported southwest from the Georgia Lake pegmatite is also clearly identified in both the geochemistry and indicator mineral data. Further work is being completed on the till samples to indicate prospectivity of the region for other deposits. - 37 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Study area for the project. Highways and towns are labeled. Ice flow directions indicated by white arrows with the corresponding flow event as the number beside (1: older, 2: younger). Surficial geology mapping area is indicated by the dash box. Till sample locations are circles. - 38 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Geochemistry, Petrogenesis, and Mineralization of the Makwa Deposit, Bird River Sill HARDING, Myles1 and HOLLINGS, Pete1 1 Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, On P7B 1J4, Canada. The Maskwa West-Dumbarton layered mafic-ultramafic intrusion is located approximately 145 km northeast of Winnipeg, Manitoba and is host to the Ni-Cu-PGE Makwa Deposit. The intrusion is related to the 2743 ± 0.5 Ma Bird River Sill (BRS; Scoates and Scoates, 2013) which is approximately 15-25km long and is made up of several separated ~800m thick differentiated mafic-ultramafic intrusive bodies. The Maskwa West-Dumbarton intrusion is emplaced into the mafic metavolcanic MORB-type massive to pillowed basalt Northern Lamprey Falls Formation (Mealin, 2008, Duguet et al., 2009). After the discovery of the Maskwa deposit in 1975, a year later 332,000 tonnes of nickel copper ore was mined in a shallow open pit (Grid Metals Corporation, 2024). In 2004 Mustang Minerals (now Grid Metals Corporation) acquired the property and have since completed extensive drilling and geophysical surveys targeting PGE mineralization. The approximately 5 km long Maskwa West-Dumbarton intrusion is composed of a ~500m thick upper gabbro-anorthositic section and a ~500m thick lower section of metaperidotite-metapyroxenite (Mustang Minerals Corp., 2014). The intrusion has been metamorphosed to the lower amphibolite facies (Coats and Buchan, 1979) with primary igneous textures Maskwa West-Dumbarton obscured or completely overprinted by alteration. The Makwa deposit is a conventional basal accumulation type magmatic sulphide deposit with the highest grade mineralization hosted within the lowest portion of the ultramafic series (Grid Metals Corporation, 2024). The deposit is comprised of a magmatic assemblage of disseminated to net textured and semi-massive pyrrhotite-pentlandite-chalcopyrite as well as low sulphide platinum group minerals (PGM) mineralization (Grid Metals Corporation, 2024). The open pit resources at Makwa are indicated to be 14.2 million tonnes with 0.48% nickel, 0.11% copper, 0.02% cobalt, 0.37 g/t palladium, and 0.10 g/t platinum (Grid Metals Corporation, 2024). The most recent up to date resource estimate for the high-grade zone indicates 4.8 million tonnes with a grade of 0.89% nickel and a 1.26% nickel equivalent (Grid Metals Corporation, 2024). The purpose of this project is to characterize the stratigraphy of the Maskwa-Dumbarton body and Ni-Cu-PGE mineralization. Assess the effects of alteration on the mineralogy, trace element geochemistry, and ore remobilization. A fence of five drill holes covering the stratigraphy of the intrusion were selected for this project where 151 core samples were collected. Forty polished thin sections were cut in representative areas for petrographic and scanning electron microscope (SEM) analysis. 141 of those samples were selected for whole rock geochemical analysis. A combination of petrographic and geochemical analysis was used to characterize the Makwa mafic and ultramafic rocks. Primary mineralogy is almost entirely replaced (Fig. 1) therefore preserved relict cumulus textures along with whole rock geochemistry are utilized to determine primary mineralogical composition. The Makwa ultramafic samples dominantly plot as Mg-rich cumulates within the komatiite field (Fig. 2) displaying a trend of Fe-enrichment highlighting strong fractionation. The results of this study will be used to determine the evolution, geotectonic setting, and sulfur source of the sulphides. REFERENCES Coats, C. J. A., & Buchan, R. (1979). Petrology of serpentinized metamorphic olivine, Bird River Sill, Manitoba. Canadian Mineralogist, 17, 847–855. Duguet, M., Gilbert, H.P., Corkery, M.T. and Lin, S. (2009): Geology and structure of the Bird River Belt, southeastern Manitoba (NTS 52L5 and 6): reprinted with revisions; in Report of Activities 2006, Manitoba Science, Technology, Energy and Mines, Manitoba Geological Survey, p. 170–183. Grid Metals Corp. – Combined Makwa and Mayville Project, Technical Report NI 43-101 – June 14, 2024 - 39 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Mealin, C. A., & University of Waterloo. Department of Earth Sciences. (2008). Geology, geochemistry and Cr-Ni-Cu-PGE mineralization of the Bird River sill evidence for a multiple intrusion model. University of Waterloo. Mustang Minerals Corp. – Combined Makwa and Mayville Project, #2098 Technical Report NI 43-101 – April 30, 2014 Scoates, J. S., & Scoates, R. F. J. (2013). Age of the Bird River Sill, southeastern Manitoba, Canada, with implications for the secular variation of layered intrusion-hosted stratiform chromite mineralization. Economic Geology and the Bulletin of the Society of Economic Geologists, 108(4), 895–907. Figure 1. Photomicrograph (XPL) of Makwa peridotite displaying mesh-textured serpentine replacing metamorphic blade shaped olivine in net-textured sulphides. Figure 2. Jensen Cation Plot highlighting Makwa Mg-rich cumulates dominantly within the komatiite field displaying Fe and Al-enrichment trends highlighting strong fractionation. - 40 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Using Anisotropy of Magnetic Susceptibility and U-Pb Geochronology from the Bush Lake Granite, Florence County, WI to Understand Post-Penokean Continental Growth HELLRUNG, Alyssa1, DROUBI, Omar Khalil1, RUGGLES, Claire1, and BONAMICI, Chloë1 Department of Geosciences, University of Wisconsin-Madison, 1215 W. Dayton Street, Madison, Wisconsin, 53706, USA 1 The Bush Lake granite in Florence County, Wisconsin, is well suited to constrain the timing of granitic magmatism relative to Proterozoic deformation events as the youngest intrusion in the Dunbar Gneiss Dome. The Dunbar Gneiss Dome is south of the Niagara fault zone, which marks the suture of the Pembine-Wausau terrane to the Superior craton during the 1.85 Ga Penokean orogeny (Schulz and Cannon, 2007). This suture may have been reactivated during later orogenic events, such as the ca. 1.75 Ga Yavapai orogeny, the ca. 1.65 Ga Mazatzal orogeny, and/or the ca. 1.45 Ga Baraboo orogeny. Emplacement and deformation of the Bush Lake granite determined through U-Pb geochronology, microstructural analysis, and anisotropy of magnetic susceptibility (AMS) fabric data provides insight into the tectonic history of the region. The Bush Lake granite is a weakly peraluminous biotite granite that contains quartz, plagioclase, megacrystic alkali feldspar, and accessory allanite, zircon, titanite, and apatite. Microstructures in the Bush Lake granite indicate variable solid-state deformation, including interlobate grain boundaries and undulose extinction in quartz, as well as grain size reduction of quartz and feldspar. Magnetic mineralogy, which informs the AMS fabric, is dominated by paramagnetic biotite with trace magnetic oxides. AMS fabrics generally record NW-SE striking foliations and moderately plunging to subvertical lineations (Figure 1), which are consistent with predominantly NE-SW shortening at a high angle to the Niagara fault zone and associated vertical thickening of the crust. Based on solid-state deformation microstructures, this magnetic fabric formed after emplacement and crystallization of the unit and records a younger period of deformation than previously thought. Cathodoluminescence (CL) imaging shows that most Bush Lake zircons preserve oscillatory zoning of likely magmatic origin, though many zircon crystals also have irregular, disturbed zoning and low-CL regions consistent with alteration. The Bush Lake granite was previously interpreted to have intruded at ~1835 Ma as a late-stage intrusion of the Paleoproterozoic Penokean orogeny, coeval with other nearby granites (Sims et al., 1985). Based on U-Pb SIMS analyses of zircon, the Bush Lake granite is interpreted to have emplaced at 1749 ± 1 Ma, making it coeval with the 1754 ± 11 Ma Amberg granite, ~28 km southwest (Holm et al., 2005), rather than the more proximal ~1835 Ma granites in the Dunbar Gneiss Dome. Solid-state deformation recorded by the Bush Lake granite may signify a broader regional deformation event in northern Wisconsin after 1750 Ma, possibly related to re-activation of the Niagara Fault Zone during the Yavapai orogeny or later events. REFERENCES Holm, D. K., Van Schmus, W. R., MacNeil, L. C., Boerboom, T. J., Schweitzer, D., and Schneider, D., 2005. U-Pb zircon geochronology of Paleoproterozoic plutons from the northern midcontinent, USA: Evidence for subduction flip and continued convergence after geon 18 Penokean orogenesis. Geological Society of America, 117(3/4), 259-275. Schulz, K. J., and Cannon, W. F., 2007. The Penokean orogeny in the Lake Superior region. Precambrian Research, 157(14), 4-25. Sims, P. K., Peterman, Z. E., and Schulz, K. J., 1985. The Dunbar Gneiss-granitoid dome: Implications for early Proterozoic tectonic evolution of northern Wisconsin. Geological Society of America Bulletin, 96, 1101-1112. - 41 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Simplified geologic map of the Bush Lake pluton (pink) in Florence, Wisconsin, with sample locations plotted and colored by average magnetic susceptibility [SI]. Lower hemisphere equal area net projections bordering the map show the AMS foliation plane and lineation at each site for each specimen. At each site, ≥ 2 rock samples are collected from different parts of the outcrop to test for slumping. Sample BL07 is an example of a failed test with two distinct sample groupings and does not provide reproducible data. - 42 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Can we improve the bouguer gravity resolution in the Cuyuna Range? Increasing gravity measurements in a region of high gravity station density. HIRSCH, Aaron1 1 Minnesota Geological Survey, University of Minnesota, 2609 Territorial Road, St. Paul MN 55114 In East-central Minnesota, the Cuyuna-Penokean orogen is made up of deformed Precambrian rocks of the Penokean-Fold-Thrust belt and adjacent terranes. This complexly folded and thermally overprinted region hosts the 2nd largest known manganese occurrences in the US (Cannon et al., 2017) and has been mined intermittently since the early 1900s. Despite decades of mining, mapping the geology is difficult with most of the bedrock overlain by thick glacial sediments from multiple glacial advances. Mapping of this critical resource and the surrounding region has relied on very limited outcrops, historical mining records, drill core, and geophysical datasets. The Minnesota Geological Survey (MGS) houses state-wide aeromagnetic, gravity, and rock property geophysical datasets that are a key tool in mapping the bedrock geology. The MGS gravity database consists of over 60,000 variably spaced measurements (Chandler et al., 2010). In the Cuyuna-Penokean area, specifically the areas around the Emily District, North Range, and parts of the South Range, the average gravity measurement spacing is ~1.6km with select areas at 0.8-1km. Station spacing of this density is generally considered very good coverage for regional geologic modeling. Due to the complex geology of the area, the MGS set out to determine if increased gravity data will further improve the geophysical resolution and subsequent geologic mapping. Over three field seasons, as part of an Earth Mapping Resources Initiative (Earth MRI) funded project, 210 new gravity points were measured, processed, and added to the gravity database. Gravity stations were tied to an existing base station, and three new field base stations were created in the area to reduce gravity loops. Measurements were prioritized along five transects perpendicular to structure: 2 North-South and 3 Northwest-Southeast profiles. Due to the varying age and accuracy of the gravity database and base stations, tie-point measurements were made at existing gravity station locations for comparison and if any corrections were needed. Multiple comparisons were made between the original and updated datasets with raw 2D Bouguer gravity profiles and gridded Bouguer gravity and second vertical derivatives analyzed (Blakely, 1996). An increase in gravity measurement density resulted in variable differences along profiles resulted in less smoothing and small shifts in slope in some regions but little to no difference in others. Both Bouguer and 2nd vertical derivative gravity grids showed significantly less variability due to inherent smoothing from the minimum curvature gridding process. Two-dimensional modeling was also performed to assess the impact of increased gravity measurement density to geologic mapping. REFERENCES Blakely, R. J.,1996, Potential Theory in Gravity and Magnetic Applications (441 p.). Cambridge: Cambridge University Press. Cannon, W.F., Kimball, B.E., and Corathers, L.A., 2017, Manganese, in chapter L of Schulz, K.J., DeYounge, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources of the United States – Economic and environmental geology and prospects for future supply: USGS Professional Paper 1802, p. L1–L28. Chandler, V. W., Lively, R. S., and Wahl, T. E., 2010, Gravity and Aeromagnetic Data Grids of Minnesota, Minnesota Geological Survey, http://purl.umn.edu/92939 - 43 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Bouguer gravity map of the Emily District, North Range, and South Range. Black dots are the existing gravity stations. Triangles are the new gravity stations. Circle in bottom left corner is the base station used for this study. Gravity values range from -14.9 - -67.8 mGals. - 44 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Using epidote and chlorite mineral chemistry to extend the alteration footprint around the Hemlo Au deposit, N. Ontario HOLLINGS, Pete1, VRZOVSKI, Joseph1, COOKE, David2, and GORNER, Emily1 1 2 Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, P7B 5E1, Canada CODES, University of Tasmania, Private Bag 79, 7001, Hobart, Australia The Hemlo deposit is a world class Archean Au deposit situated in Northern Ontario, Canada with historic production of >21 Moz of Au over 35 years of continuous operation. The deposit has a strike length of ~3 km with a well-documented alteration footprint surrounding mineralization. LA-ICPMS analyses of epidote, chlorite and pyrite from within and surrounding the deposit (Fig. 1) have identified major and trace element variations in mineral chemistry that allow for the discrimination of deposit-proximal and deposit-distal signatures. Epidote compositions vary with distance from Hemlo, with the highest concentrations of As and Sb in epidote proximal to the mineralized zones. Anomalous trace element compositions in epidote can be detected up to 1.5 km further than the mapped alteration footprint. Chlorite also displayed variation in trace elements with deposit-proximal chlorite displaying exponentially higher Ti/Sr and V/Co values than deposit-distal and intrusion-related chlorite. The Ti/Sr ratio for chlorite expanded the geochemical footprint of the Hemlo deposit by up to 1 km. Pyrite displayed anomalous enrichments in a number of elements, with Au, Te and As proving to be the most effective pathfinder elements in pyrite as they were detected at anomalous concentrations up to 2.5 km from the deposit. Several post-mineralization intrusions that surround the deposit were evaluated using epidote and chlorite chemistry to assess whether they generated any false positive geochemical anomalies. The distal post-mineralization intrusions have epidote with consistently low As and Sb concentrations and elevated Fe/Al values relative to deposit-related epidote and can be easily distinguished. Intrusion- Figure 1. Location of samples collected for this study - 45 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 related chlorite displayed low Ti/Sr and V/Co values relative to the deposit chlorite and was also found to be more enriched in Fe relative to deposit-proximal chlorite. These results indicate that the postmineralization intrusions did not produce false positive mineral chemistry anomalies. Variations in chlorite Fe-Mg content can be tracked spectrally using the position of the diagnostic 2250 nm absorption feature. Chlorite displays a range of wavelengths from 2240 – 2256 nm throughout the Hemlo district. Chlorite with lower wavelengths (< 2248 nm) display lower average Fe/Mg (<1) values whereas chlorite with longer wavelengths (> 2252 nm) display higher Fe/ Mg (>1) values. Spectral variations 1550 nm absorption feature of epidote can be used to track compositional variations between the Fe-(epidote) and Al-(clinozoisite) epidote group endmembers. Epidote throughout the Hemlo area displayed a range of wavelengths from 1540 – 1564 nm. These variations in spectral features of epidote could be correlated to epidote major element variations with wavelengths > 1550 nm having on average lower Fe/Al values (< 0.8), whereas wavelengths < 1448 nm displayed average Fe/Al values of ~1. The systematic variations in syn-mineralisation epidote and chlorite compositions around Hemlo suggests that methods developed for investigating geochemical footprints defined by green rock alteration around porphyry systems may also be applicable to Archean orogenic gold deposits. - 46 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Petrographic Study of Granular Iron Formation in the Gunflint Formation: Evidence for WellOxygenated Surface Waters JONSSON, Justin1 and LI, Zhiquan2 Ontario Geological Survey, Ministry of Energy and Mines, Suite B002, 435 James St. South Thunder Bay, ON P7E 6S7 Canada 1 2 Department of Geology, Lakehead University, 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada Granular iron formation (GIF) exhibits distinct features compared to banded iron formation (BIF), being characterized by granule-rich textures and commonly interpreted as detrital, with some grains derived from sedimentary reworking of iron-rich clays, mudstones, arenites, and even stromatolites. Other granules consist of concentric hematite cortices that likely precipitated from Fe(II)-rich waters upon interaction with oxygenated shallow seawater. Previous studies have demonstrated that GIF provides valuable insights into shallow marine environments, as physical energy from waves, tides, and storms is largely restricted to depths above the storm wave base. The 1.88 Ga Gunflint Formation comprises both BIF and GIF, along with chert, carbonates, and minor siliciclastic materials, deposited on a storm-dominated continental shelf. In this study, we examine the petrography of GIF from the lower Gunflint Formation to identify evidence for redox variations in a shallow marine environment. Thin sections of the GIF commonly exhibit oolitic textures, with subordinate peloids and oncoids. Ooids and oncoids are typically composed of hematite, whereas peloids commonly consist of a chert core with hematite rims. Most granules display well-developed concentric hematite cortices, suggesting that iron oxides were directly precipitated from an Fe(II)-rich water column. The grains are not uniformly in contact with one another; instead, many appear to be suspended within the matrix, indicating co-deposition of granules with silica gel. Approximately 30% of the matrix consists of carbonate material, which is randomly distributed within the chert matrix. Hematite grains in the GIF exhibit platy to needle-like morphologies, with grain sizes generally less than 15 µm. Most grains fall within the 1–5 µm range, suggesting an authigenic origin. Some ooids contain manganese carbonates within their inner rims, similar to those observed in the matrix, indicating Mn enrichment in bottom sediments. Our findings suggest that during the early depositional stage of the Gunflint Formation, bottom sediments of the surface water were enriched in Mn, indicating that surface waters were sufficiently oxidizing to promote the precipitation of Mn oxides. However, subsequent early burial of organic matter may have facilitated Mn reduction. Importantly, redox conditions in the shallow marine environment appear to have been oxidizing enough to preserve Fe oxides, but not sufficiently oxidizing to retain Mn oxides. The occurrence of bacterial reduction suggests an increase in organic carbon burial during this time, potentially associated with enhanced primary productivity; however, further investigation is required. - 47 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Interactive Geospatial Geoheritage: Efforts to Support Place-based Exploration and Digitally Preserve Keweenaw’s Geoheritage LIZZADRO-MCPHERSON, Daniel J.1, VYE, Erika C.1, 2, DeGRAFF, James M.2, and ROSE, William I.2 The Great Lakes Research Center, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 USA 1 Department of Geological and Mining Engineering Sciences, Michigan Technological University, 630 Dow Environmental Sciences, 1400 Townsend Drive, Houghton, MI 49931 USA 2 The Keweenaw Peninsula, renowned for many superlatives – world’s largest native copper deposit, first major industrial mining complex in the United States – continues to inspire scientists, historians, and the general public. Ongoing geoheritage efforts enable these groups to explore the deep connections between the underlying geology, landforms, mining industry, and the people working and living on this land for over a millennia. Geoheritage uses a structured approach to identify, manage, and protect geosites and areas with geologic features of significant scientific, educational, cultural, or aesthetic value. Grassroots efforts, spearheaded by Bill Rose, have raised awareness and elevated the prestige of Keweenaw Geoheritage on the global stage despite lacking any formal designation. Bill’s efforts with others to create the first U.S. Geoheritage Park is still in the development stage, while other efforts led by Michigan Technological University (MTU) personnel are helping to bring Bill’s dream to fruition through two geospatial projects: 1) the Keweenaw Geoheritage Geodatabase and companion webGIS-viewer; and 2) Preservation, Indexing, and Enhanced Utility of Historic Copper Mining Drill Hole Records. The Keweenaw Geoheritage geodatabase and webGIS-viewer serve as a living atlas designed to facilitate ways of understanding relationships people hold with the Keweenaw’s geology. The publicly accessible interactive map explores how geology influences education, conservation, and sustainable economic development initiatives in the region (Fig. 1). Each geosite provides a) a brief description of how the site contributes to Keweenaw’s Geoheritage, b) a 360-view, and c) a description of the scientific, educational, cultural, economic, and aesthetic significance of the site (Lizzadro-McPherson & Vye, 2024). This effort supports the co-stewardship of cultural heritage, restoration of legacy mining sites, conservation issues, and the development of economic opportunities based on the region’s globally significant geology. The diamond drill hole (DDH) project aims to digitally preserve at-risk paper core logs, map DDH locations and details, and produce a robust database with a webGIS-based finding aid. The DDH core records document the more recent history of exploratory drilling by the copper mining industry (1899-1970) and contain information still relevant to geological research and exploration for critical minerals. The inventory of records is a tabular database of transcriptions of down-hole data from each scanned core log. An interactive webmap-based finding aid with PDF records and tables of interval descriptions on an open access data portal is in development. These innovative, interactive, geospatial resources aim to enhance scientific inquiry and broaden public engagement and exploration of Keweenaw’s iconic geologic landscape. REFERENCES Lizzadro-McPherson, D.J., and Vye, E.C. (2024). Keweenaw Geoheritage Geodatabase. Michigan State Geological Survey; U.S. Geological Survey, National Cooperative Geologic Mapping Program (Award #G23AC00285 FY23). - 48 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Fig. 2: Diamond drill hole record (left) and mapped surface location with metadata for Suffolk Exploration drilling campaign (right). Fig. 1: Keweenaw Geoheritage Viewer with pop-up displaying the core geoheritage values of the geosite at Great Sand Bay, Keweenaw County, MI. Fig. 2: Diamond drill hole record (left) and mapped surface location with metadata for Suffolk Exploration drilling campaign (right). - 49 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Implications of recent geochronology on the regional geology and timing of gold mineralization in the Red Lake greenstone belt, Ontario MACDONALD, Peter1, HASTIE, Evan1, MALEGUS, Paul2, KAMO, Sandra3, HAMILTON, Mike3 and MARSH, Jeff4 Earth Resources and Geoscience Mapping Section, Ontario Geological Survey, 933 Ramsey Lake Rd, Sudbury, ON P3E 6B5, Canada 1 2 Resident Geologist Program, Ontario Geological Survey, 227 Howey St, Red Lake, ON P0V 2M0, Canada Jack Satterly Geochronology Laboratory, Department of Earth Sciences, University of Toronto, 22 Ursula Franklin St, Toronto, ON, M5S 3B1, Canada 3 Mineral Exploration Research Centre, Harquail School of Earth Sciences, Laurentian University, 935 Ramsey Lake Rd, Sudbury, ON P3E 2C6, Canada 4 As part of the Ontario Geological Survey’s Red Lake bedrock mapping compilation project, geochronology samples were collected from the Red Lake gold camp to improve the ages of volcanic assemblages, sedimentary units and intrusive suites. Eighteen samples were analyzed using ID-TIMS and LA‑ICP‑MS uranium/lead methods on zircon grains. The new ages suggest significant revisions to the geographic presence and/or stratigraphy of the Balmer, Ball, Trout Bay and Confederation assemblages; as well as expanding the regional presence of the Huston conglomerates and identifying the presence of English River terrane sedimentation in the Uchi Subprovince. Newly dated intrusions from throughout the belt refine the timing of synvolcanic, syntectonic, and post‑tectonic magmatism, along with improving the known timing of early gold mineralization and later remobilization. Geochronology from the LP Fault highlights a sequence of felsic and porphyritic intrusive magmatism that is coeval with known gold mineralizing events in the main camp. - 50 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Quantitative analysis of iron mineral composition and crystal sizes in the contact metamorphosed Biwabik iron formation and the Bald Eagle intrusion, NE, MN, USA. MARIN LÓPEZ, Valentina1, BRENGMAN, Latisha1, EYSTER, Athena,2 MITCHELL, Jennifer3, PU, Xiaofei4, MANGUM, John4, and WALKER, Patrick4 Department of Earth and Environmental Sciences, University of Minnesota Duluth, Heller Hall, 1114 Kirby Drive, Duluth, MN 55812, USA 1 2 Department of Earth and Climate Sciences, Tufts University, Lane Hall, 2 North Hill Road, Medford, MA 02155, USA Characterization Facility and the Department of Earth and Environmental Science, University of Minnesota, Twin Cities, S-104 John T. Tate Hall, 116 Church Street Se, Minneapolis, MN 55455, USA 3 4 The National Laboratory of the Rockies, 15013 Denver West Parkway, Golden, CO 80401 Integrated experimental, theoretical, and field data demonstrate the potential viability of hydrogen production via subsurface fluid-rock interaction in systems with significant ferrous iron content (Mayhew et al., 2018; Ellison et al., 2021; Geymond et al., 2022; 2023; 2025; Templeton et al., 2024). As olivine is a key mineral of interest for hydrogen generation either through natural water-rock interaction, or engineered production, we focus on quantifying mineral compositions, crystal size distributions, and modal mineralogy in lithologic units from northeast Minnesota to enable future quantification of hydrogen production feasibility. Units of focus are the troctolitic portion of the Bald Eagle Intrusion (BEI; drill core LOD-6, n=16 samples), and the olivine-rich contact metamorphosed Biwabik iron formation (drill cores 8041 and 8016, n=12 and 13 samples respectively). Olivine and serpentine crystal size distributions (CSD) were quantified using image-based analysis. Combining 2D CSD measurements from BEI depths 970, 1091, and 1212.5 feet (n = 407 crystals from 3 samples; Figure 1A) yielded 8.0% partially serpentinized olivine, and 35.2% fully serpentinized olivine, with the remaining 56.8% of the sample composed of plagioclase, oxides, and minor phases external to olivine crystals. Olivine compositions (Fo76) are similar across BEI samples from multiple depths. In addition to olivine, BEI samples contain pyroxenes, labradorite, and titanium-bearing magnetite and ilmenite, with serpentine-group minerals present along key fracture sets. Reaction boundaries between olivine and serpentine were observed using transmission electron microscopy (TEM; Figure 1B, C). Serpentines are either amorphous or nano-crystalline with variations in crystallinity dependent on orientation in the fracture. Banding was observed in both Focused Ion Beam sections within serpentines proximal to olivine edges (Figure 1C). In metamorphosed Biwabik iron formation samples, olivine compositions are iron-rich (Fo12). In addition to olivine, meta-iron-formation samples contain quartz, oxides, sulfides, pyroxenes, amphiboles, chlorite, mica, calcite, with minor amounts of garnet, plagioclase, serpentine, and accessory phases. CSD analysis of metamorphosed iron formation sample 8016-271 (n = 190 crystals from 1 sample) yielded 55.3% olivine. Next steps include comparison of 2D CSD analyses with 3D X-ray computed tomography data. Overall, the presence of abundant olivine indicates the area could be of interest for future hydrogen generation. To quantify hydrogen generation potential, heterogeneity between serpentinized and un-serpentinized zones should be quantified to extend data from the mineral to the intrusion and formation scale, in addition to connecting hydrologic, geomechanical, and geochemical parameters to mineral data. Next steps include workflow modifications to improve scalability, and application of the workflow to the contact metamorphism Biwabik iron formation. - 51 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1. Image-based CSD analysis and Transmission electron microscopy images for sample LOD-6-1212.5. A) Traces of olivine and serpentine crystals in thin section with mineral proportions calculated using CSD analysis after Higgins, 2000. B) STEM image of reaction boundary between olivine and serpentine. C) TEM image of serpentine and olivine boundary. Top right diffraction pattern of serpentine with a green oval around planes (001) and (002) where the brightest area shows direction of growth of serpentine. Green arrows show crystal orientation. Bottom right diffraction pattern of olivine. REFERENCES Ellison, E. T., Templeton, A. S., Zeigler, S. D., Mayhew, L. E., Kelemen, P. B., Matter, J. M., et al. (2021). Low-temperature hydrogen formation during aqueous alteration of serpentinized peridotite in the Samail ophiolite. J. Geophys. Res. Solid Earth 126, e2021JB021981. doi:10.1029/2021JB021981. Geymond, U., Briolet, T., Combaudon, V., Sissmann, O., Martinez, I., Duttine, M., & Moretti, I. (2023). Reassessing the role of magnetite during natural hydrogen generation. Frontiers in Earth Science (Lausanne), 11. https://doi.org/10.3389/ feart.2023.1169356 Geymond, U., Truche, L., Sissmann, O., Kubániová, D., Recham, N., & Martinez, I. (2025). Mineralogical changes and H2 generation yield during hydrothermal alteration of a magnetite-siderite assemblage. Journal of Geophysical Research: Solid Earth, 130, e2024JB030724. https://doi.org/10.1029/2024JB030724 Higgins, M. (2000). Measurement of crystal size distributions. American Mineralogist , 85 (9): 1105–1116. https://doi. org/10.2138/am-2000-8-901 Mayhew, L. E., Ellison, E. T., Miller, H. M., Kelemen, P. B., and Templeton, A. S. (2018). Iron transformations during low temperature alteration of variably serpentinized rocks from the Samail ophiolite, Oman. Geochimica Cosmochimica Acta 222, 704–728. doi:10.1016/j.gca.2017.11.023 Templeton, A. S., Ellison, E. T., Kelemen, P. B., Leong, J., Boyd, E. S., Colman, D. R., & Matter, J. M. (2024). Low-temperature hydrogen production and consumption in partially-hydrated peridotites in Oman: implications for stimulated geological hydrogen production. Frontiers in Geochemistry, 2. https://doi.org/10.3389/fgeoc.2024.1366268. - 52 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Models of the regional gravity and magnetic anomalies associated with the Nipigon Embayment NITESCU, Bogdan1, TORRES, David Santiago1, and GAONA, Jorge Mario1 1 Department of Geosciences, Universidad de los Andes, Cra. 1 Nº 18A - 12 Bogotá, Colombia The Nipigon Embayment, a region dominated by Proterozoic rocks around Lake Nipigon, extends northward for approx. 150 km into the Superior craton from the Nipigon/Thunder Bay region on the northern shore of Lake Superior. The Embayment is characterized by the presence of intruded maficultramafic rocks and diabase sills dating from the early magmatic stage of Keweenawan rifting in Lake Superior (Heaman et al., 2007). The relationship between the Nipigon Embayment and the MCR has long been a topic of scientific investigation. Various researchers proposed that the Nipigon Embayment represents a viable candidate for a possible third branch of the MCR system (e.g., Hinze and Chandler, 2020), based on various lines of evidence, such as the existence of mafic-ultramafic igneous rocks in the upper crust with geochemical and geochronological similarities to the MCR rocks (e.g., Heaman et al. 2007; Hollings et al., 2007), and the anomalous upper mantle beneath the region reflected in weak seismic anisotropy (Ola et al., 2016), low velocity (Frederiksen et al., 2007; 2013; Foster et al., 2020), and electrical resistivity (Ferguson et al., 2005). However, some investigators suggest that the Nipigon Embayment is related to pre-existing structures, arguing against this region representing a third branch of the MCR due to its lack of Keweenawan extensional features (e.g., Hart and MacDonald, 2007). In this contribution, the gravity and magnetic regional anomalies associated with parts of the Nipigon Embayment are evaluated, both qualitatively, using various filters, and quantitatively, using 2.5D forward modelling. The positive mass anomalies that account for the regional gravity highs in the area covered by the Nipigon sills are equivocal and could be related either to Nipigon magmatic rocks or to covered older rocks bodies, such as Archean mafic-ultramafic intrusions and greenstone belts. If it is assumed that some of these anomalies are related to the Nipigon magmatic rocks, then the gravity models suggest the existence of structures that may have acted as feeders for the emplacement of the Nipigon Embayment mafic-ultramafic intrusive bodies and diabase sills. The Figure 1: 2.5D forward model of the Bouguer gravity anomaly along an W-E profile in the northern part of the Nipigon Embayment, assuming that the cause of the anomaly is related to Nipigon magmatic rocks. Density values: Nipigon magmatic rocks 2.89 g/cc; greenstone belt mafic rocks 2.9 g/cc; granitoid and tonalite 2.64 g/cc; background 2.67 g/cc. - 53 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 magnetic models of the regional magnetic anomalies indicate the presence of a significant subsurface volume of highly magnetic rocks within the Nipigon Embayment crust. These results are compatible with the interpretation of this region as a segment of the crust affected by magmatism in the initiation stage of the MCR, possibly as an incipient, undeveloped part of the rift controlled by pre-existing structures. REFERENCES Ferguson, I.J., Craven, J.A., Kurtz, R.D., Boerner, D.E., Bailey, R.C., Wu, X., Orellana, M.R., Spratt, J., Wennberg, G., Norton, M., 2005. Geoelectric response of Archean lithosphere in the western Superior Province, central Canada. Phy. Earth Planet Int. 150, 123–142. https://doi.org/10.1016/j.pepi.2004.08.025 Foster, A., Darbyshire, F., Schaeffer, A., 2020. Anisotropic structure of the central North American Craton surrounding the Mid-Continent Rift: Evidence from Rayleigh waves. Prec. Res. 342, 105662. https://doi.org/10.1016/j. precamres.2020.105662. Frederiksen, A.W., Miong, S.K., Darbyshire, F.A., Eaton, D.W., Rondenay, S., Sol, S., 2007. Lithospheric variations across the Superior Province Ontario, Canada: Evidence from tomography and shear wave splitting. J. Geophys. Res-Earth 112, 1–20. https://doi.org/10.1029/2006JB004861. Frederiksen, A.W., Bollmann, T., Darbyshire, F., van der Lee, S., 2013. Modification of continental lithosphere by tectonic processes: A tomographic image of central North America. J. Geophys. Res-Earth 118, 1051–1066. https://doi. org/10.1002/jgrb.50060. Hart, T.R., MacDonald, C.A., 2007. Proterozoic and Archean geology of the Nipigon Embayment: Implications for emplacement of the Mesoproterozoic Nipigon diabase sills and mafic to ultramafic intrusions. Can. J. Earth Sci. 44, 1021–1040. https://doi.org/10.1139/e07-026. Heaman, L.M., Easton, R.M., Hart, T., MacDonald, C.A., Hollings, P., Smyk, M., 2007. Further refinement to the timing of Mesoproterozoic magmatism Lake Nipigon region, Ontario. Can. J. Earth Sci. 44, 1055–1086. https://doi. org/10.1139/e06-117. Hinze, W.J., Chandler, V.W., 2020. Reviewing the configuration and extent of the Midcontinent rift system. Prec.Res. 342, 105688. https://doi.org/10.1016/j.precamres.2020.105688. Hollings, P., Hart, T., Richardson, A., MacDonald, C.A., 2007a. Geochemistry of the Mesoproterozoic intrusive rocks of the Nipigon Embayment, northwestern Ontario: Evaluating the earliest phases of rift development. Can. J. Earth Sci. 44, 1087–1110. https://doi.org/10.1139/e06-127. Ola, O., Frederiksen, A.W., Bollmann, T., van der Lee, S., Darbyshire, F., Wolin, E., Revenaugh, J., Stein, C., Stein, S., Wysession, M., 2016. Anisotropic zonation in the lithosphere of Central North America: Influence of a strong cratonic lithosphere on the Mid-Continent Rift. Tectonophysics 683, 367–381. https://doi.org/10.1016/j.tecto.2016.06.031. - 54 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Origin of the World-Class Eagle, Eagle East, and Tamarack Ni-Cu-PGE Deposits and comparative analysis with other Midcontinent Rift- and Siberian Trap-related intrusions NOWAK, Robert1, DEERING, Chad1 , and ESSIG, Espree1 Department of Geological and Mining Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA 1 The 1.1 Ga Mesoproterozoic Midcontinent rift hosts the Eagle, Eagle East, and Tamarack Ni-CuPGE deposits and Embayment Prospect. These deposits are hosted by ultramafic igneous rocks and have some of the highest Ni-Cu grades on Earth. We use new bulk-rock data and published datasets (bulk-rock, mineral chemistry, and isotopic analyses) to examine major, minor, and trace element trends of both Midcontinent rift-related alkaline and tholeiitic intrusions (Nowak et al., 2025). In addition, we compare the geochemical data to local kimberlite-hosted lower-crustal xenoliths and local igneous (Archean) and sedimentary (Paleoproterozoic) country rocks. We found the peridotite magma compositions dominantly consist of primitive mantle compositions with varying abundances of subduction-related components, alkaline-transitional melts, and local country rock contaminates (e.g., Baraga and Animikie Basin sediments). The subduction-related components are interpreted to be derived from previous Archean and Paleoproterozoic subduction events and likely hosted within the sub-continental lithospheric mantle. Importantly, these subduction-related components are also interpreted to have acted as oxidizing agents within the melt, stabilizing sulfate (+2 FMQ (fayalite–magnetite–quartz) to FMQ) while inhibiting sulfide crystallization as the magma ascended through ~50 km of the Superior craton. This study largely corroborates the previous findings with respect to the contribution of local country rock contamination to the Eagle–Tamarack peridotite host rocks, which is estimated to be minimal (<5%). However, the incorporation of <5% reductive pelitic siltstone contamination results in strong shifts in the oxygen fugacity of the peridotite melt, from +2 FMQ to slightly below FMQ, as determined from spinel Fe3+/∑Fe ratios (Figure 1). This shift in oxygen fugacity resulted in the transition from total sulfate (+2 FMQ) to sulfate + sulfide (<+2 FMQ to FMQ) to total sulfide (<FMQ). This shift in oxygen fugacity is a key contributor to the formation of Ni-Cu-PGE-rich massive sulfides within the Eagle peridotite. This study presents an expanded geochemical interpretation for the exploration of Midcontinent rift-related Ni-Cu-PGE deposits to include peridotites with subduction-like signatures and contaminated via <5% reductive sedimentary country rocks. Based on these findings, we also comparatively analyze geochemical samples from Figure 1: Downhole profiles of drillhole 03EA034 of Fe3+/∑Fe ratios of spinel (Ding et al., 2010); with oxygen fugacity estimates (relative to FMQ) this study), Ni, Cu, and S (all in wt%; this study), and the relative proportion (%) of compositions (eclogite, amphibolite, subducted sediment, alkaline-transitional, and Baraga Basin sediments) used to reconstruct the multielement compositions of Eagle peridotite. Analytical error (accuracy; 1σ) is estimated to be smaller than the symbol size. - 55 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Midcontinent rift-related prospective intrusions and Siberian-Trap-related intrusions in order to better determine economic vs. subeconomic host rock signatures. REFERENCES Ding, X., Li, C., Ripley, E.M., Rossell, D., Kamo, S., 2010, The Eagle and East Eagle sulfide ore-bearing mafic-ultramafic intrusions in the Midcontinent Rift System, upper Michigan. Geochronology and petrologic evolution. G3 Geochem. Geophys. Geosyst., 11, p.1-22. Nowak, R., Deering, C., and Essig, E., 2025, Origin of the World-Class Eagle, Eagle East, and Tamarack Ni-Cu-PGE Deposits. Minerals, 15, 871. https://doi.org/10.3390/min15080871 - 56 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 BEDROCK GEOLOGY OF THE ERICSBURG NW, ERICSBURG NE, RAY SW, AND RAY SE QUADRANGLES, ST. LOUIS AND KOOCHICHING COUNTIES, MINNESOTA NOWARIAK, Eric and SEVERSON, Allison Minnesota Geological Survey, University of Minnesota – Twin Cities, 2609 Territorial Road St. Paul, MN, USA New geologic mapping presented here portrays the Precambrian bedrock geology and tectonic history of the axial zone of the Quetico subprovince across four 7.5’ quadrangles in portions of eastcentral Koochiching County and far western St. Louis County, Minnesota. The map records the Neoarchean deposition, deformation, metamorphism, and migmatization of turbiditic sediments, along with the intrusion of the granitic rocks of the Vermilion Granitic Complex during the accretion of the Wawa subprovince to the southern margin of the Superior Province, and continuing through the intrusion of the Paleoproterozoic Fort Frances dike swarm. The metasedimentary rocks of the Quetico subprovince, now predominantly biotite schist, granofels, and migmatite, have been subject to at least four successive contractional and transpressional deformation styles documented in the map area. The map pattern and dominant structural grain of bedrock is controlled by structures associated with D2 and D3 deformation. D2 deformation produced map-scale, tight to isoclinal F2 folds with well-developed ENE-WSW-striking subvertical S2 axial-planar foliation. D3 deformation coincides with the development of ENE- and NW-trending ductile shear zones with dextral motion. F3 folds are coaxial to F2 folds and manifest as isoclinal refolds and reorientations of D2 structures. D4 deformation post-dates the dominant D2 and D3 deformational events and is represented by steeply plunging broad, open folds and NNW-trending fault and fracture zones. New geochemical analyses illustrate rocks of the Vermilion Granitic Complex are generally calkalkaline, weakly peraluminous to metaluminous, magnesian granitoids with minor amphibole-rich dioritic to gabbroic rocks. Based on geological and geochemical features, the Vermilion Granitic Complex can be subdivided into groups with distinct lithologies, geochemistry, and magma sources. Tonalites, trondhjemites, and granodiorites (TTG) of the Early Magmatic Suite are distinctly more sodic than the younger Lac La Croix Suite granitoids. Compared to the Early Magmatic Suite, Lac La Croix Suite granitoids are relatively more alkalic, more aluminous, and have steeper REE profiles. Quetico metasedimentary rocks and the Vermilion Granitic Complex have been subject to at least two metamorphic events recording the burial, uplift, and intrusive history of the subprovince. M1 metamorphism is likely contemporaneous with D2 and early D3 deformation, based on the presence of syn- and post-kinematic, inclusion-rich porphyroblasts. Peak metamorphic conditions reached amphibolite facies during M1 and have been constrained to 525-575°C with pressures exceeding 6 kbars based on phase equilibrium modeling outside the thermal influence of the Lac La Croix Suite. Proximal to the Lac La Croix granite, M1 metamorphic features have been overprinted by a hightemperature, low-pressure event, M2, presumably due to the intrusion of voluminous granitoids of the Lac La Croix Suite during the waning stages of D3 deformation. M2 metamorphism manifests as inclusion-poor garnet, sillimanite-, cordierite-, and andalusite-bearing assemblages in metasediments and granitic orthogneisses. - 57 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1. A. Plutonic rock classification of igneous rocks in this study, after Enrique and Esteve, 2019. B. 2ACNK (2* molar Al2O5/(CaO+Na2O+K2O), Na2O/K2O, 2 FMSB (2*(FeOtot+MgO)wt.%*(Sr+Ba)wt.%) source identification diagram, of Laurent and others (2014). Fields for TTG (T), continental or C-type (C), and metasomatized mantle or M-type (M) granitoids from Moyen (2019) have been added. C. Alumina Saturation plot after Barton and Young (2002) for all intrusive units within the map area. - 58 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Petrographic, geochemical, and mineralogical analyses of manganiferous iron formations and associated lithologies at the Cuyuna Range, central Minnesota PALIEWICZ, Cory1, POST, Sara1, and THAKURTA, Joyashish1 Natural Resources Research Institute (NRRI), University of Minnesota Duluth, 5013 Miller Trunk Hwy, Duluth, MN 55811 USA 1 The Paleoproterozoic Cuyuna Range of central Minnesota hosts one of two significant manganese deposits in the United States and contains anomalously high manganese concentrations (up to ~50 Wt. % Mn) when compared to other Banded Iron Formations in the Lake Superior region (Cannon et al., 2017). The area was highly deformed and metamorphosed during the Penokean Orogeny and encompasses the Emily District at edge of the Animikie Basin to the north, and the North and South ranges which occur within the older fold and thrust belt to the south (Boerboom and Chandler, 2004; Southwick et al., 1988; Morey, 1990). Although the area has a rich history of iron mining and ongoing manganese exploration, many questions remain regarding the occurrence, nature, and mechanisms of manganese mineralization. This work includes new petrographic, lithogeochemical, and mineralogical data collected and analyzed from 201 drill core samples from 37 drill holes across the Emily District, North Range, and South Range (Figure 1). The regional pilot study is part of a larger USGS Earth Mapping Resources Initiative to map and better-constrain the mineral potential of the region. We emphasize the lithologic variability of mineralized iron formations throughout the range, but especially within the Emily District, which from past studies is known to be most-enriched in Mn-content. Cuyuna iron formations generally range from cherty to slaty (thick bedded to thin bedded / granular to non-granular) with manganiferous units extending from enriched (5-10% Mn), manganiferous (>10 % Mn) and highly manganiferous (>35 % Mn). Although textural and mineralogical differences of mineralized units vary widely with increasing grade, the variability and significance of non-enriched lithologies throughout the Cuyuna Range also offer insights regarding possible sources or mechanisms of mineralization, especially when taken within the context of recently integrated historic drill logs and prior works (e.g., McSwiggen et al., 1995). Textural and mineralogical variation among mineralized units exhibit many signs of hydrothermal modification during manganese enrichment. Many grains have been replaced with manganese oxides and hydroxides in both cherty and slaty iron formations and the occurrence of vugs associated with other hydrothermal accessory minerals such as carbonates, epidote, micas, and clays, along with abundant sieved and altered grains indicate that many pulses of variable hydrothermal activity likely resulted in disequilibrium of most preserved mineral assemblages. Non-mineralized units such as graywackes are typically highly altered to sericite and kaolinite and pyritic graphitic argillites have been observed to exhibit non isochemical characteristics illustrating high mobility of Fe and Mn. The occurrence of silicified and oxidized zones as they relate to variations of grade are also characterized along with variability of downhole changes of Mn, Fe, SiO2, Al2O3, and LOI plotted as split logs which also show changes of Co, Cu, and Zn to further assess the possibility of other critical minerals associated with manganese. - 59 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Geologic map after Boerboom and Chandler (2004; 2022) showing drill hole locations sampled in Crow Wing and Aitkin Counties, central Minnesota. REFERENCES Boerboom, T.J., and Chandler, V. W., 2004, Plate 2 - Bedrock Geology, in Setterholm, D. R. Geologic atlas of Crow Wing County, Minnesota, MGS County Geologic Atlas, C-16 Part A, 1:100,000. Boerboom, T.J., and Chandler, V. W., 2022, Plate 2 - Bedrock Geology, in Bauer, et al., 2022. Geologic atlas of Aitkin County, Minnesota, MGS County Geologic Atlas, C-52 Part A, 1:200,000. Cannon, W.F., Kimball, B.E., and Corathers, L.A., 2017, Manganese, in chap. L of Schulz, K.J., DeYoung, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources of the United States—Economic and environmental geology and prospects for future supply: USGS Professional Paper 1802, p. L1–L28. McSwiggen, P.L., Morey, G.B., and Cleland, J.M., 1995, Iron-formation protolith and genesis, Cuyuna range, Minnesota: Minnesota Geological Survey Report of Investigations 45, 54 p. Morey, G.B., 1990, Geology and manganese resources of the Cuyuna iron range, east-central Minnesota: Minnesota Geological Survey Information Circular 32, 28 p. Southwick, D.L., Morey, G.B., and McSwiggen, P.L., 1988, Geologic map (scale 1:250,000) of the Penokean orogen, central and eastern Minnesota, and accompanying text: Minnesota Geological Survey Report of Investigations 37, 25 p., 1 pl. - 60 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Physical Magmatic System Interpretation of the Marathon Cu-Pd Deposit, Coldwell Complex, Ontario PETERSON, Dean1, STEINER, R. Alex1, SWEET, Gabriel1, and BOUCHER, Chanelle2 1 2 Big Rock Exploration, 2505 West Superior Street, Duluth, MN 55806. Generation PGM Inc., 100 King Street West, Toronto, ON M5X 1B1. The goal of geologic mapping and/or drill core logging in mafic magmatic ore deposits is to not just know what the lithology is at a specific outcrop and/or drill hole interval, but to know with some confidence where you are in the mineralized intrusion, i.e., within the overall magmatic system. Generation Mining (GenM) contracted Big Rock Exploration (BRE) to reevaluate the Coldwell Complex hosted Marathon Cu-Pd deposit using a magmatic system approach. Mineralized mafic intrusions are typically composed of three principal minerals, plagioclase-olivinepyroxene along with various proportions of apatite, Fe-Ti oxides, and Fe-Cu-Ni sulfides. Variations in mineralogic estimates of the three principal minerals by many geologists over decades of time can be the difference between calling a rock an anorthosite, a gabbro, a troctolite, or a peridotite. In deposit areas with decades upon decades of exploration history, these basic lithologic calls by many different geologists can directly influence how a mafic magmatic ore deposit is interpreted and/or modeled. Problems in interpretation can come to the forefront when drill hole intervals are logged strictly by lithology and subsequently digitally assigned a LithCode. Another method of logging and interpreting mineralized mafic intrusions is to approach it from the physical process side, i.e., as a magmatic system. Utilizing a magmatic system approach begins with an understanding of the initial conditions of the system. Initial conditions include the intrusive geometry and Figure 1. Schematic model of the magmatic architecture of the Marathon Cu-Pd deposit. - 61 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 flow paths, the lithology of the footwall, hangingwall and sidewall rocks, and the magmas composition, crystallinity, plagioclase-olivine phenocryst content, trace element signature and sulfide content. In general terms, mafic intrusions have slower moving marginal boundaries, which are commonly xenolithrich, surrounding a faster flowing and xenolith-poor ‘clean’ central core. Magmatic shearing is induced by the differential velocity, from margin to core, in which magmas intrude can lead to pronounced local mineralogical variability in the outcome. For example, phenocryst sorting leads to modal layering, and kinetic sieving processes raises large particles, which can be phenocrysts, autoliths and/or xenoliths, upwards in the intrusion. The rocks formed in these mafic magmatic systems, though largely governed by the initial conditions, locally can vary by associated chemical, thermal, and momentum boundaries. BRE coupled these magmatic first principals with GenM assisted field work and drillhole relogging to reevaluate the Marathon Cu-Pd deposit magmatic system. A schematic model of the interpreted magmatic system at the Marathon Cu-Pd deposit is presented in Figure 1, and stratigraphic profiles depicting the historic lithology-based coding (Lith Codes) and recently proposed magmatic systems approach coding (Unit Codes) is given in Figure 2. This talk will highlight many of BRE’s research findings on the Marathon Cu-Pd deposit magmatic system. Figure 2. The proposed magmatic system approach Unit Codes (left) versus the historic GenM Lith Codes (right) assigned to the rocks of the Marathon Cu-Pd deposit. Rectangular arrows point to how logged lithologies can be assembled into discrete magmatic system units of the Marathon Series. - 62 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Critical Mineral Potential of the Watersmeet Gneiss Dome, MI USA QUIGLEY, Ashley1, MAHIN, Robert1, and GAMET, Nolan1 1 Michigan Geological Survey, 416 Avenue C, Gwinn, MI 49841U.S.A. Precambrian gneisses and schists on the northern margin of the Watersmeet Dome in Michigan’s Upper Peninsula are unusually enriched in rare earth elements, fluorite and incompatible elements including U, Th, Hf, and Zr (Barovich et al., 1991; Sims, 1990). Rocks are mainly Archean gneisses and amphibolites although elevated REEs, fluorite and incompatible elements are associated with a gneiss and schist unit of possible Paleoproterozoic age (Barovich et al., 1991). The area is within Earth Mapping Resources Initiative (EMRI) critical mineral focus areas for both IOCG/ IOA and Magmatic REE deposits (Dicken and others, 2022). The Michigan Geological Survey (MGS) conducted detailed geologic mapping and sampling, as well as collected geophysical and geochronological data. An RS-230 BGO gamma-ray spectrometer was used to take over 600 total gamma (K/U/Th) measurements from outcrops. Additionally, an unmanned aerial vehicle (UAV), high resolution magnetic survey was flown. A previously undescribed magnetic, fine-grained schist comprised 85% of the highest total REE samples (high of 1659 ppm TREE). The schists are associated with magnetite and fluorite and coincide with a kilometer-wide central magnetic anomaly, as well as a three kilometer, roughly east-west trending, sinuous anomaly. In plots, granitoids, gneisses, and schists show three distinct populations. Group 1 clusters in the VAG-syn/COLG field, has no europium anomaly and average 72 ppm TREE. Group 2 is transitional between VAG-syn/ COLG and WPG, has a marked europium depletion, and contains an average of 136 ppm TREE. Group 3 is enriched in REE with an average 711 ppm TREE, plots in the WPG/A-Type granite field and has moderate europium depletion. All three groups are peraluminous. Group 3 rocks include enriched REE magnetic schists, magnetic granitoids, and gneisses all of which are located in proximity to each other as well as to magnetic highs. Highly fractionated, non-peralkaline felsic granites can have geochemical characteristics which overlap those for typical A-type granites Figure 1: Map showing the location of the Watersmeet project area. - 63 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 (Whalen and others, 1987). Some fractionation is indicated in Group 1 and Group 2 rocks by a semicontinuous trend of decreasing Zr, Nb, Ce, and Y. Group 3, however, displays no such evidence of fractionation, which is typical of A-Type granites. Numerous REE, F, Th, and/or U-bearing silicate, oxide and carbonate minerals including fluorite, thorite, pyrochlore, allanite, columbite, parasite, and yttrialite were identified using SEM within alteration halos along fractures and occasionally within veins. Zircons with strong pleochroic halos are common, particularly within biotite grains but also observed with amphiboles. The presence of fluorite and REE bearing-fluorocarbonates indicate that REE enrichment was facilitated, at least in part, by fluorine-rich hydrothermal fluids. Preliminary, unpublished U-Pb zircon geochronology indicate that all units are Archean and the previous proposed Paleoproterozoic ages may represent a thermal resetting event. REFERENCES Barovich, K.M., Patchett, P.J., Peterman, Z.E., and Sims, P.K., 1991. Neodymium Isotopic​Evidence for Early Proterozoic Units in the Watersmeet Gneiss Dome, Northern​Michigan. U.S. Geological Survey Bulletin 1904-G: G1-G7. ​ Dicken, C.L., Woodruff, L.G., Hammarstrom, J.M., and Crocker, K.E., 2022, GIS,​supplemental data table, and references for focus areas of potential domestic resources​of critical minerals and related commodities in the United States and Puerto Rico (ver.2.0, April 2024): U.S. Geological Survey data release, https://doi.org/10.5066/P9DIZ9N8. Pearce, Julian & Harris, Nigel & Tindle, Andrew. (1984). Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks. Journal of Petrology. 25. 956-983. 10.1093/petrology/25.4.956.​ Sims, P.K., 1990, Geologic map of Precambrian rocks, Marenisco, Thayer, and​ Watersmeet 15-minute quadrangles, Gogebic and Ontonagon counties, Michigan, and​ Vilas County, Wisconsin: U.S. Geological Survey Miscellaneous Investigations Series Map​I-2093, scale 1:62,500.​ Whalen, J.B., Currie, K.L. & Chappell, B.W. A-type granites: geochemical characteristics, discrimination and petrogenesis. Contrib Mineral Petrol 95, 407–419 (1987). https://doi.org/10.1007/BF0040220. - 64 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Current geologic and geophysical research on the Precambrian basement of eastern North Dakota, USA SAINI-EIDUKAT, Bernhardt1, CHITTICK, Steve2, and NESHEIM, Timothy2 1 2 Dept. of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58102 USA North Dakota Geological Survey, Grand Forks, ND 58202 USA In the entirety of the state of North Dakota, no crystalline basement is exposed due to Phanerozoic sedimentary cover. Regional geophysical mapping, combined with lithological data and radiometric dates, have correlated the Wabigoon and Wawa subprovinces of the Superior Craton into eastern North Dakota (Figure 1). However, understanding of the geologic and the geophysical characteristics of the basement in this region is, with some exceptions, relatively poor compared to many other areas (Figure 2). Figure 1: Map of North Dakota Precambrian geology, RRVD drill core locations, and proposed survey area (black outline). Open symbols: geochronology samples. Base map from Sims et al. (1991). Figure 2: Regional aeromagnetic map, and proposed survey area (blue outline), showing the difference in resolution between ND and MN. (The NE corner of ND does already have higher quality aeromagnetic data.) - 65 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 The North Dakota Geological Survey (NDGS), working with the Earth Mapping Resources Initiative (Earth MRI) of the U.S Geological Survey (USGS) (www.usgs.gov/special-topics/earthmri), and North Dakota State University are undertaking a renewed initiative to obtain high quality geochronologic, geochemical, geophysical, and radiometric data over eastern North Dakota. Depth to basement is on the order of a few hundred meters in eastern ND, but increases to thousands of meters westward underneath the Williston Basin. For that reason, the focus of the initiative is on the eastern region where depth to basement is less than 1000 m. As part of Earth MRI, the USGS is planning to carry out a high-resolution airborne magnetic and radiometric survey in eastern North Dakota, to be flown in 2026-27. The survey will be designed to meet complementary needs related to geologic mapping and mineral resource research. The survey design is being coordinated with the NDGS to provide complete coverage of a region that crosses the boundaries of multiple subprovinces and greenstone belts within the Archean Superior Province. The mineral systems of interest in the survey area include Mafic magmatic, Porphyry Sn, and Metamorphic. Potential critical mineral commodities include Cr, PGE, Au, Co, graphite, REE, Li, Ta, and Sn. There is additional potential for Mn, Ni, Cu, Fe, Mg, and Cs. Samples of drill core from the 1977 Red River scientific drilling project (Moore, 1978; Kelley, 1980; Beaudry et al., 2024, Pereira et al., 2024), and from other cores, will undergo geochemical, geochronological, petrological, and geophysical investigation. Portable XRF analysis for trace elements is underway, as is a gravimetric survey of eastern ND by the NDGS. REFERENCES Beaudry, C., Hess, M., Pereira, C., Saini-Eidukat, B., 2024, Petrology and geochemistry of Precambrian basement rocks in Walsh County, North Dakota. ILSG Abstr. and Proc., v.70, part 1, p. 6-7. Kelley, L.I., 1980, Kaolinitic weathering zone on Precambrian basement rocks, Red River Valley, eastern North Dakota and northwestern Minnesota. M.S. Thesis, University of North Dakota. 85 pp. Moore, W. L., 1978. A preliminary report on the geology of the Red River Valley Drilling Project, eastern North Dakota and northwestern Minnesota: Bendix Field Engineering Company Subcontract H77-059-E, 292p. https://www.osti.gov/ biblio/6538603 doi:10.2172/6538603 Pereira, C., Nesheim, T., Vervoort, J.D., and Saini-Eidukat, B., 2024, Major element geochemistry and first zircon U-Pb age dates of Precambrian basement rocks in eastern North Dakota. ILSG Abstracts and Proceedings, v.70, part 1, p.74-75. Sims, P.K., Peterman, Z.E., Hildenbrand, T.G., and Mahan, S., 1991, Precambrian Basement Map of the Trans-Hudson Orogen and adjacent terranes, northern Great Plains, U.S.A.: USGS Miscellaneous Investigations Series Map, I-2214. DOI: 10.3133/i2214 - 66 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Reassessing variations in metamorphism across the Penokean orogen in Northern Michigan: Part 1, new Pressure-Temperature-Time-Deformation constraints SALERNO, R.1, CANNON, W. F.1, THOMPSON, J. M.2, SOUDERS, A. K.2, VERVOORT J.3, and HILLENBRAND, I.2 1 2 3 U.S. Geological Survey, Reston, VA 20192, USA U.S. Geological Survey, Denver, CO 80225, USA Washington State University, Pullman, WA 99163, USA The Penokean orogeny (1890-1830 Ma) represents the earliest collisional event in a long subduction sequence active throughout the Paleoproterozoic to Mesoproterozoic along Laurentia’s southern margin. Traditionally, spatial variations in metamorphic grade in the Penokean orogenic belt were described as three “nodes” (Fig. 1) and ascribed to the main accretionary phase which ended at 1830 Ma. However, the swath of younger 40Ar/39Ar cooling ages at ~1750 Ma across the terrane suggests later collisional episodes also played an important role in modifying the Penokean orogenic belt (Schneider et al., 1996). This observation, coupled with newly mapped younger structures by recent geophysical surveys, raises questions about which features are truly Penokean in origin, and which reflect later overprinting by younger tectonic events (Drenth et al., 2021). Elucidating the causes and timing of post-Penokean modification of crust in central Laurentia is key for accurately reconstructing the outward growth of proto-North America throughout the Proterozoic. We have used multiple geochronometers and isotope systems to unravel the metamorphic evolution of the Penokean orogenic belt. New geochronology and thermodynamic modeling of metasedimentary rocks reveal variations in the timing of metamorphism and subsequent cooling histories between metamorphic nodes (Fig. 1). Directly adjacent to the Niagara fault zone, rocks in the Peavy node have garnet Lu-Hf ages of 1837±7 Ma, reflecting the age of granulite facies metamorphism in the lower crust. Overlapping garnet Sm-Nd (1830±65 Ma) and apatite U-Pb (1822±28 Ma) ages indicate rapid exhumation of these lower crustal rocks near the end of the Penokean orogeny. In contrast, rocks in the Watersmeet and Republic nodes, located farther inboard from the paleomargin, reflect later lowergrade amphibolite facies regional metamorphism after the end of the Penokean orogeny, from 1825±5 to 1782±15 Ma. Unlike the Peavy node, these samples have offset Lu-Hf and Sm-Nd ages reflecting the different closure temperatures of the two isotope systems in garnet. Dispersed Lu-Hf and Sm-Nd ages indicate prolonged residence of these rocks at mid-crustal depths and correspond with protracted cooling paths of 1-3°C/Mya, until final exhumation began at ~1750 Ma. Our results illustrate that the metamorphic nodes in the Penokean orogenic belt do not reflect the same conditions or cooling histories, and do not all represent the same tectonic event. Instead, our data reveal a sequence where early granulite facies metamorphism and rapid exhumation are linked with the end stages of the Penokean orogeny and are restricted to the belt of high-grade rocks north of the Niagara fault. Regional amphibolite facies metamorphism persisted after, requiring continued crustal thickening following both the accretionary phase of the Penokean orogeny and exhumation of deep crustal rocks. The implications of this are two-fold. 1) The metamorphic nodes in the Penokean orogenic belt are not cogenetic but rather reflect different tectonic events and different times. 2) Post-Penokean regional metamorphism followed by widespread uplift and cooling after ~1750 Ma represent significant modification of the Penokean orogenic belt throughout Geon-17. More broadly, younger overprinting on this terrane reveals that outboard tectonic activity following the Penokean orogeny played a major role in the modification of Paleoproterozoic and Archean crust in central Laurentia. - 67 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Top, generalized geologic map showing metamorphic nodes in the Penokean orogen in northern Michigan and sample locations in our study (map after Tinkham and Marshak, 2004). Bottom, temperature-time diagrams showing cooling histories of garnet-bearing rocks in three metamorphic nodes. Microstructures indicate deformation during uplift at ~1750 Ma proceeded after peak metamorphism. 40Ar/39Ar data are from previous studies and references are compiled in Salerno et al. (2026). REFERENCES Drenth, B.J., Cannon, W.F., Schulz, K.J., and Ayuso, R.A., 2021, Geophysical insights into Paleoproterozoic tectonics along the southern margin of the Superior Province, central Upper Peninsula, Michigan, USA: Precambrian Research, v. 359, doi:10.1016/j.precamres.2021.106205. Salerno, R., Cannon, W.F., Thompson, J.M., Souders, A.K., Vervoort, J., Hillenbrand, I., 2026, Unraveling protracted modification of Archean and Paleoproterozoic crust in central Laurentia, Penokean orogen, with garnet and accessory mineral geochronology and microstructural analysis: Geological Society of America Bulletin, in press. Schneider, D., Holm, D., and Lux, D., 1996, On the origin of Early Proterozoic gneiss domes and metamorphic nodes, northern Michigan: Canadian Journal of Earth Sciences, v. 33, p. 1053–1053, doi:10.1139/e96-080. Tinkham, D.K., and Marshak, S., 2004, Precambrian dome-and-keel structure in the Penokean orogenic belt of northern Michigan, USA, in Whitney, D.L., Teyssier, C., and Siddoway, C.S., eds., Gneiss Domes in Orogeny: Geological Society of America Special Paper, v. 380, p. 321-338, doi:10.1130/0-8137-2380-9.321. - 68 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Whole Rock and Mineral Chemistry of the Eagle’s Nest Intrusion, McFaulds Lake Greenstone Belt, Ontario, Canada: Insights into the Origin and Paragenesis SHESHNEV, Vlad1, HOLLINGS, Pete1, TOLLEY, James1, ANGOMBE, Moses1, DELLER, Matt2, and STERN, Richard3 1 2 3 Department of Geology, Lakehead University, Thunder Bay, Ontario, Canada Wyloo, Thunder Bay, Ontario, Canada Canadian Centre for Isotopic Microanalysis, University of Alberta, Edmonton, Alberta, Canada Orthomagmatic Ni-Cu-(PGE) deposits originate in the mantle, where source composition and degree of partial melting are the first-order controls on composition and metal fertility of the derived magmas (Naldrett, 2011). During ascent, these magmas undergo differentiation, producing more evolved compositions that reflect both the characteristics of the mantle source and subsequent magmatic processes (Barnes, 2023; Smith et al., 2024). The Eagle’s Nest intrusion is a maficultramafic, blade-shaped dike, which is host to the only known economically significant Ni-Cu-(PGE) mineralization within Meso- to Neoarchean McFaulds Lake Greenstone Belt. The Eagle’s Nest is part of the mafic to ultramafic magmatism of the Koper Lake subsuite, of the larger Ring of Fire Intrusive Suite (ca. 2736–2732 Ma; Houlé et al., 2020; Metsaranta and Houlé, 2020). Two different parental magma compositions have been proposed for the Eagle’s Nest intrusion, including a low- and a highMg komatiitic magma, both of which are inconsistent with the observed mineralogy of the intrusion (Mungall et al., 2010; Zuccarelli, 2020). To better understand the origin and nature of the Eagle’s Nest intrusion, this study integrated petrography, whole-rock geochemistry, mineral chemistry, as well as radiogenic and stable isotope systematics. The Eagle’s Nest intrusion can be subdivided into the marginal and inner zones. The marginal zone comprises mafic intrusive rock in contact with the wall rock tonalite, exhibiting the most evolved mineralogical and geochemical characteristics. The marginal zone gradationally transitions into the inner zone, which consists of ortho- to mesocumulate ultramafic rocks with more primitive compositions, reflecting the accumulation of olivine and chromite in cotectic proportions, along with variable amounts of intercumulus silicate phases and interstitial sulfides. Using the whole rock geochemistry of olivine-chromite cotectic cumulate rocks, combined with olivine and chromite mineral chemistry, a new parental magma composition was determined for the Eagle’s Nest intrusion. The new estimate suggests a komatiitic basalt magma that contained ~11 wt% FeOt and ~15 wt% MgO. The new parental magma estimate is more evolved than previously proposed compositions, however, it is consistent with the composition of identified chilled margins, associated mafic dikes, and olivine from the Eagle’s Nest intrusion. Using the newly obtained estimate, the petrographically determined crystallization sequence was recreated at low pressures, suggesting the Eagle’s Nest formed in shallow crustal levels. Whole-rock geochemistry and Sm-Nd isotopes indicate that the Eagle’s Nest magma was derived from a depleted mantle source above the garnet stability field. During transport, this magma underwent crustal contamination by the host tonalite and older supracrustal rocks. Assimilation of sulfur-bearing supracrustal material likely triggered sulfide saturation, supported by the mass-independent fractionation values of the measured Δ³³S. The intrusion’s distinct petrological and metallogenic features likely reflect both the emplacement dynamics and the parental magma composition, resulting in its unique metal endowments within the greenstone belt. REFERENCES Barnes, S.J., 2023. Lithogeochemistry in exploration for intrusion-hosted magmatic Ni-Cu-Co deposits. Geochemistry: Exploration, Environment, Analysis, vol. 23(1), pp. geochem2022–025. Houlé, M.G., Lesher, C.M., Metsaranta, R.T., Sappin, A.-A., Carson, H.J.E., Schetselaar, E.M., McNicoll, V.J., and Laudadio, A., 2020. Magmatic architecture of the Esker intrusive complex in the Ring of Fire intrusive suite, McFaulds Lake - 69 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 greenstone belt, Superior Province, Ontario: Implications for the genesis of Cr and Ni-Cu-(PGE) mineralization in an inflationary dyke-chonolith-sill complex, in Bleeker, W., and Houlé M.G. (eds). Targeted Geoscience Initiative 5, Geological Survey of Canada, Open File 8722, pp. 141–163. Metsaranta, R.T., and Houlé, M.G., 2020. Precambrian geology of the McFaulds Lake “Ring of Fire” region, northern Ontario. Ontario Geological Survey, Open File Report 6359, 260 p. Mungall, J.E., Harvey, J.D., Balch, S.J., Azar, B., Atkinson, J., and Hamilton, M.A., 2010. Eagle’s Nest a Magmatic NiSulfide Deposit in the James Bay Lowlands, Ontario, Canada, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, Volume II: Zinc-Lead, Nickel-Copper-PGE, and Uranium. Society of Economic Geologists, Special Publication 15, pp. 539–557. Naldrett, A.J., 2011, Fundamentals of Magmatic Sulfide Deposits. Reviews in Economic Geology, vol. 17, pp. 1–50. Smith, W.D., Jenkins, C.M., Augustin, C.T., Virtanen, V.J., Vukmanovic, Z., and O’Driscoll, B., 2024. Layered intrusions in the Precambrian: Observations and perspectives. Precambrian Research, 50th Anniversary Invited Review, vol. 415, 107615. Zuccarelli, N., 2020. Sulfide textures, geochemistry, and genesis of the Komatiite-Associated Eagle’s Nest Ni-Cu-(PGE) Deposit, McFaulds Lake Greenstone Belt, Superior Province, Ontario. MSc Thesis, Laurentian University, Sudbury, Ontario, Canada, 108 p. - 70 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Integrating petrophysical data with full tensor magnetic gradiometry for improved interpretation and modelling of remanently magnetized intrusions in the Midcontinent Rift SMITH, Jennifer1, KASKI, Krista1, TSCHIRHART, Victoria1, and ENKIN, Randy1. 1 Natural Resources Canada, Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8 Magnetic surveys are widely used in mineral exploration to detect and delineate subsurface structures and ore-bearing systems. As near-surface, high-grade deposits become increasingly rare, exploration is shifting toward deeper targets and more complex geological settings. Full tensor magnetic gradiometry (FTMG), particularly when deployed with highly sensitive SQUID-based quantum sensors, provides high-resolution measurements of all components of the magnetic field gradient tensor, offering enhanced imaging of subtle geological structures and ore bodies that conventional total magnetic intensity (TMI) surveys may not resolve (Rudd et al., 2022). FTMG reduces the influence of regional magnetic fields, diurnal variations, and cultural noise, supporting more robust 3D inversion and geological interpretation. Despite these advantages, adoption of FTMG has been limited by logistical complexity, depth constraints, and a lack of publicly available datasets particularly in geologically complex or remanently magnetized areas. To address this, the Geological Survey of Canada is acquiring and openly disseminating precompetitive SQUID-based FTMG datasets (e.g. Fig. 1), providing real-world data for benchmarking inversion workflows and testing emerging quantum sensors. Figure 1: Maps of the total magnetic intensity (TMI) (a), and three components of the magnetic gradient tensor: Bxx (b), Byy (c) and Bzz (d) over the Escape Intrusion within the Thunder Bay North Intrusive Complex of the Midcontinent Rift. The Midcontinent Rift (MCR) provides a geologically complex environment to evaluate FTMG in remanently magnetized settings. Mafic-ultramafic conduit-type intrusions in this region, including the Escape and Current intrusions of the Thunder Bay North Intrusive Complex (TBNIC), exhibit strong remanent magnetization, generating distinct and heterogeneous magnetic anomalies (Kaski et al., 2024; Fig. 1). These characteristics make the MCR an ideal setting to assess how FTMG resolves both induced and remanent magnetic components. In this study, we integrate SQUID-based FTMG inversions with petrophysical, petrographic, and geochemical data, including magnetic susceptibility, natural remanent magnetization, and mineralogical composition, to examine how lithologic variability, serpentinization, and magnetic mineral development influence the intensity and orientation of remanent magnetization, providing a more geologically realistic framework for interpretation and modeling. Preliminary results show that integrating FTMG with rock property data improves resolution of key geological contacts and remanent magnetic sources, enabling more robust 3D modeling of conduithosted Ni-Cu-PGE systems. This study highlights the value of combining high-resolution geophysical and petrophysical datasets for interpreting complex magnetic anomalies. - 71 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 REFERENCES Kaski, K., Smith, J., Tschirhart, V.L., and Heggie, G., 2024, 3D magnetic-susceptibility and magnetization vector inversions of remanently magnetized conduit-type Ni deposits: a case study from the Thunder Bay North intrusive complex, Ontario: Geological Survey of Canada, Open File 9209, 25 p, https://doi.org/10.4095/pkwpmf1tju Rudd, J., Chubak, G., LaNier, H., Stolz, R., Schiffler, M., Zakosarenko, V., Schneider, M., Schulz, M., Meyer, M., 2022, Commercial operation of a SQUID-based airborne magnetic gradiometer: Leading Edge. https://doi.org/10.1190/ tle41070486.1 - 72 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Optimizing data collection for better geological interpretations and adding value to your project SMYK, Emily1, DOLEGA, Simon1, CHURCHLEY, Jeffrey1, and FLANK, Steven1 1 Bayside Geoscience Inc., 1179 Carrick St. Thunder Bay, ON P7B 6M3 “Data are disembodied information. Data are not the same as knowledge.” ~ W. Olsen (2012) A well-designed field or drill program is developed from the beginning to produce substantiated, appropriate and robust datasets. However, data are commonly considered interchangeable with interpretations and are often misreported to fit a geologist’s bias within the context of a project. Common instances of data distortion include: (1) identifying and classifying rocks as pre-named units with assumed occurrences; (2) designating altered rocks as separate lithologies; (3) recording qualitative descriptions rather than quantitative variables; (4) not standardizing all aspects of data collection; and (5) generating incomplete geochemical datasets in the pursuit of select geochemical data. It is a human instinct to apply human interpretations to systematic rocks and processes, but collecting purely observational, quantified geologic data can provide significantly more flexible information during later interpretation. Some findings may emerge from a dataset without being expected or predicted in advance (Olsen, 2012). More ‘expected’ findings might follow the usual predictable patterns, but unpredictable trends may be obfuscated by unintentionally engineered data biases. The most impactful approach to optimize data collection procedures is standardizing all data input for recording rock identification and descriptions, photos, and QA/QC practices. Collecting alteration, mineralization, and structural data as separate data to the lithology, rather than integrated into lithology names (e.g., carbonatized basalt), allows for separation of different datasets for multiple applications and discourages segregating single rock units due to varying characteristics. Many issues are resolved by generating mandatory fields that can only be populated by standardized terms using drop-down menus. Another approach is quantifying and binning as many descriptors as possible. A simple change is including mineral abundance ranges in mineral description fields. For example, describing weak epidote alteration as ‘Weak (2-5%)’ provides a quantitative visual cue to the core logger/mapper, ensuring consistent descriptions and binning similar mineral percentages together. Another consideration is developing sampling programs that submit all samples for consistent analytical packages. Cost-saving measures are often implemented by selectively submitting samples for different packages or only submitting samples that are anticipated to return good assay data. These practices can identify high-grade samples, but can also miss secondary, unpredictable mineralization. Without a range of geochemical data, it is impossible to assess truly elevated values from background values. Purely objective geologic data can provide new interpretations depending on the approach/aims of the geologist. Consistent and comprehensive data collection may produce unexpected results and provide a valuable final product – a strong asset that increases the value of a project, property, or deposit. REFERENCES Olsen, W. (2012). Data Collection: Key Debates and Methods in Social Research. Sage Publications Ltd. - 73 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Pukaskwa Redux: Revisiting and Reconnecting with Superior’s Wild North Shore SMYK, Mark1, HODGE, Joanna2 and ROBILLARD, Carly3 1 Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1 Canada Canadian Federation of Earth Sciences, University of Ottawa, 150 Louis Pasteur Private, Ottawa ON K1N 6N5 Canada 2 3 Parks Canada, Pukaskwa National Park, PO Box 212, Heron Bay, ON, P0T 1R0 Canada In August, 2025, the Senior Author served as Geologist-in-Residence (GIR) at Pukaskwa National Park, on Lake Superior near Marathon. The GIR program at Pukaskwa is a partnership between the Canadian Federation of Earth Sciences and Parks Canada, with volunteer expenses funded by the APGO Education Foundation. It is a two-week, volunteer position that started at Pukaskwa in 2022. The role of the GIR is to highlight Pukaskwa’s remarkable geological features and to educate park visitors and Parks Canada interpretive staff about the local geology. Guided hikes, “walk and talk” sessions, drop-in opportunities and presentations were employed to convey knowledge and messaging. As a result of the 2025 GIR program, ideas are being considered to develop a self-guided geology field trip for the readily accessible “front country” trails at Pukaskwa that expose a variety of Neoarchean supracrustal rocks of the Schreiber-Hemlo greenstone belt. Its “back country”, featuring the Coastal Hiking Trail, is underlain mainly by Neoarchean granitoids of the Pukaskwa Batholith. Archean rocks are intruded by Paleoproterozoic and Mesoproterozoic diabase dykes, the latter of which are associated with Midcontinent Rift magmatism. There are numerous features attributed to Quaternary glaciation, including prominent roches moutonnées (Figure 1), potholes and glacial polish/ striae. Modern shoreline and aeolian processes continue to redistribute sediment and create unique and critical habitats for rare and endangered plant species. The GIR program serves to remind us of the importance and value of participating in outreach activities, sharing information and underscoring the critical role that geology plays in ecological processes. The program is expanding to Fundy National Park in 2026 with the hope that further National Parks will be added in the future to provide more opportunities for geoscience outreach and education to a broader audience. Figure 1: Geologist-in-Residence, Mark Smyk, pointing out a prominent roche moutonnée at Horseshoe Beach during a guided hike of the Southern Headland Trail, Pukaskwa National Park, August, 2025 - 74 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Oxidation to Ores: Petrological Insights into Supergene Manganese Enrichment at the Emily Deposit, Minnesota STEINER, R. Alex¹, WATSON, Noa2, RILEY, Jack2, HAMMER, Mikala3, THOLE, Jeff2, FEINBERG, Josh3, SANDRI, Henry4, and SAVAGE, Brian4 ¹Big Rock Exploration LLC, 2505 W Superior Street, Duluth, MN, 55803 USA 2 3 4 Macalester College, 1600 Grand Ave, St. Paul, MN 55105 USA University of Minnesota, 116 Church Street SE, Suite 150, Minneapolis, MN 55455 USA Electric Metals (USA) Limited, 109 West 13th Street Wilmington, DE 19801 USA Electric Metals (USA) Limited’s Emily Deposit in Minnesota’s historic Cuyuna Iron Range contains zones reaching +50 wt. % manganese, making it the highest-grade manganese resource in North America and one of the highest-grade manganese deposits in the world. Manganese-oxide ores of the Emily Deposit are proposed to have formed through supergene enrichment due to deep, potentially protracted weathering of folded iron formation strata during the deposit’s 1.9-billion-year history. Weathering of manganese-bearing carbonate facies oxidizes the original rhodochrosite, drawing the manganese into solution. The manganese enriched groundwaters then migrate down-dip, along stratigraphic boundaries before redepositing manganese as oxides in the porous grainstones of the iron formation. The recent exploration drilling campaign by Electric Metals USA Limited and Big Rock Exploration provided a wealth of geologic, geochemical, and microscopic data that may be used to evaluate the hypothesized ore genesis mechanism on a deposit scale and constrain the metallurgical behavior of the ores. Here we present an analysis of a large exploration geochemical dataset using deposit-wide mass-balance calculations to determine the element mobility within the iron formation. The geochemical results are then contextualized within geology by combining optical and X-ray microscopy to identify mineral phases and phase transitions, as well as intergrowths of secondary minerals. Mass balance calculations show depletions in manganese from the weathered carbonate facies of the Emily Iron Formation and parallel enrichment of manganese into the grainstones. Integration of preliminary optical and X-ray microscopy shows a breakdown of early-formed minerals in the source carbonates and replacement by Fe-oxides and oxyhydroxides along bedding and fractures. Secondary manganese minerals appear to surround primary grains in the grainstones and may be replacing early formed ferruginous cements. These observations support the hypothesized ore-genesis model and provide the necessary information for subsequent metallurgical evaluation of the Emily Deposit including the manganese-iron-silicate mineral associations that may impact ore upgrading, grinding, and hydrometallurgical outcomes. REFERENCES Steiner, R. A., Peterson, D., Berg, T., Solie, J., Larson, M., Schaefbauer, E., Sweet, G., 2024, North Star Emily Manganese Deposit, Crow Wing County, Minnesota: Observations Interpretations, and Recommendations Following the Initial 2023 Drilling Campaign, January 17, 2024. Big Rock Exploration. - 75 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1 – Full section reflected light (above) and X-ray map showing texture of iron and manganese minerals. Areas with mixed iron and manganese minerals and pure, coarse grained manganese species are highlighted. - 76 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Timing and conditions of magmatism, metamorphism, and strain partitioning in the western Shebandowan Greenstone Belt (Superior Province) STEPHAN, Tobias1, PHILLIPS, Noah1,2, and HOLLINGS, Pete1 1 Department of Geology, Lakehead University, 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy., Los Angeles, CA, 90089-0740, United States 2 The Shebandowan Greenstone Belt is an Archean granite–greenstone terrane within the Wawa subprovince of the Superior Province, comprising calc-alkaline to tholeiitic, felsic to ultramafic supracrustal metavolcanic rocks, synvolcanic to late intrusive suites, and felsic hypabyssal dikes and sills. Despite its economic and tectonic significance, the timing and conditions of magmatism, metamorphism, and deformation remain incompletely constrained. Here, we integrate structural geology, high-precision geochronology, metamorphic petrology, and microstructural analyses to establish a coherent tectonometamorphic framework for the western belt. Strain varies from weakly deformed domains (e.g., felsic intrusions and pillow basalts) to highstrain mylonitic zones, mainly affecting diorites and metavolcanic rocks. The orientation of the main ductile foliation orientation is relatively consistent across the study area, while stretching lineations range from shallow to steep. These variations correlate with spatial changes in vorticity, reflecting strain partitioning between high-strain shear zones and coarse-grained, feldspar-rich, and thus, mechanically strong intrusive bodies (Stephan et al. 2025). Peak metamorphic conditions of ~600–700 °C are constrained by pseudosection modeling and conventional thermometry, consistent with Zr-in-titanite temperatures (570–700 °C). Retrograde conditions of ~400–500 °C are preserved in post-kinematic assemblages. Quartz microstructures, crystallographic preferred orientations, and grain-size piezometry indicate deformation at ~400–600 °C and differential stresses of ~20–60 MPa, suggesting deformation near the brittle–ductile transition. CA-ID-TIMS U-Pb zircon geochronology identifies two magmatic phases based on concordant ages: an intrusive phase at 2718 Ma (e.g. felsic intrusion of Moss Lake Stock and Obadinaw Stock) and a younger phase at 2707 Ma (e.g. Greenwater Stock). An upper intercept age constrains volcanism at 2712 Ma in the metavolcanic sequences. In situ U–Pb titanite dates of 2711±76 Ma (2σ) and 2672±100 Ma record metamorphic events spanning greenschist- to amphibolite-facies conditions. A Re-Os molybdenite age of 2708±12 Ma overlaps with both magmatism and metamorphism, linking mineralization to tectonometamorphic processes. These results indicate synkinematic magmatism and amphibolite-facies deformation under predominantly horizontal tectonics. Strain was strongly partitioned due to competency contrasts between coarse-grained intrusive rocks and fine-grained metavolcanic units. This integrated dataset provides new constraints on the coupling between magmatism, deformation, metamorphism, and mineralization in Archean granite–greenstone belts. REFERENCES Stephan, T., Phillips, N., Tiitto, H., Perez, A., Nwakanma, M., Creaser, R., and Hollings, P. 2025. Going with the flow — Changes of vorticity control gold enrichment in Archean shear zones (Shebandowan Greenstone Belt, Superior Province, Canada). Journal of Structural Geology, 201, 105542. https://doi.org/10.1016/j.jsg.2025.105542 - 77 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Subsurface mapping of the late Ordovician Maquoketa Group in eastern Wisconsin using airborne electromagnetic and well data STEWART, Esther K.1, McNALL, Natalie1, 2, HART, Dave1, AMES, Carsyn 1, CHASE, Pete1, STEWART, Eric1, and GRAHAM, G.1 Wisconsin Geological and Natural History Survey, University of Wisconsin-Madison Division of Extension, Madison, Wisconsin 53705 1 2 Department of Geosciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211 The late Ordovician Maquoketa Group is a fine-grained unit and regional aquitard separating the upper, fractured Silurian dolostone aquifer from the deep, Cambrian-Ordovician sandstone-dolomite aquifer in eastern Wisconsin. Here, the Maquoketa Group lithostratigraphy includes, from top to bottom, the Brainard Formation (marls and shale), Ft Atkinson Formation (carbonate wackstonethrough grainstone and marls), and Scales Formation (black shales and marls). The shale-rich composition of the Maquoketa Group is readily distinguished from the overlying Silurian dolostone by airborne electromagnetic (AEM) data (Minsley et al., 2022). We undertook subsurface mapping and characterization of the Maquoketa Group to address regional issues of groundwater quantity and quality. For Wisconsin users, the resulting 3D surfaces can be used as inputs to groundwater models and aid land-use decisions by providing information on the depths, thickness, and rock properties of this aquitard. We used AEM data tied to borehole logs and core to generate raster surfaces and understand facies changes and structures across study area (Figure 1). Despite cultural interference mainly from roads, the AEM data nicely imaged the top of the Maquoketa Group aquitard. The Maquoketa Group basal surface and its internal formations were imaged by the AEM data but with greater uncertainty, and the base of the unit dipped below the penetration depth of the AEM data to the east. The Maquoketa Group extends from about 850 feet (259 m) above sea level near its western subcrop extent to 100 feet (31 m) above sea level at the eastern edge of the map area, with thicknesses between about 220 – 450 ft (67 – 137 m). The north-south strike of depth-structure elevation contours is abruptly offset in three locations, labeled on Figure 1. One of these (location 2) corresponds to the Precambrian Spirit Lake Tectonic zone (Holm et al., 2007) and fault offset of Silurian bedrock (Luczaj, 2011). Several new and existing drill core tie to the AEM data in the western study area, and lithologic variation in the cores corresponds to vertical changes in the resistivity profile of the Maquoketa Group. Internal variability in the resistivity of the Maquoketa, as imaged by the AEM data, apparently decreases to the east. Future air rotary drilling will test whether this signal is due to decreased data resolution as these units dip eastward, or whether it reflects an increase in shaley facies to the east. REFERENCES Holm, D.K., Anderson, R., Boerboom, T.J., Cannon, W.F., Chandler, V., Jirsa, M., Miller, J., Schneider, D.A., Schulz, K.J. and Van Schmus, W.R., 2007. Reinterpretation of Paleoproterozoic accretionary boundaries of the north-central United States based on a new aeromagnetic-geologic compilation. Precambrian Research, 157, 71-79. Luczaj, J.A., 2011. Preliminary Geologic Map of the Buried Bedrock Surface, Brown County, Wisconsin. Wisconsin Geological and Natural History Survey Open File Report 2011-02. Minsley, B.J, Bloss, B.R., Hart, D.J., Fitzpatrick, W., Muldoon, M.A., Stewart, E.K., Hunt, R.J., James, S.R., Foks, N.L., and Komiskey, M.J., 2022. Airborne electromagnetic and magnetic survey data, northeast Wisconsin. U.S. Geological Survey data release, https://doi.org/10.5066/P93SY9LI. - 78 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Figure 1: Maps showing the elevation and thickness of the Maquoketa Group (top) and an example AEM line (below). The inset map of Wisconsin (left) shows counties outlined in black and the eastern Wisconsin study area outlined in orange. Circled numbers to the left of the top Maquoketa elevation map locate offsets in depthstructure contours. The star locates the Krepline core on the map and AEM line, and formation contacts from core are tied to AEM line. Roads and railroads, symbolized above the line, cause cultural interference with the AEM signal. - 79 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Rocks and Roots: The Role of Geoheritage in Biodiversity Stewardship STONE, Abraham1, LIZZADRO-McPHERSON, Dan2, and VYE, Erika3 Michigan Natural Features Inventory, Deborah A. Stabenow Building, 1st Floor, 525 W. Allegan St., Lansing, MI 48933, United States 1 Geospatial Research Facility, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, United States 2 Great Lakes Research Center, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, United States 3 Conservation of natural surficial landforms with regional, scientific, or cultural significance has long been an intrinsic component used by scientists and educators who follow the principles of geoheritage. On the Keweenaw Peninsula, intact outcrops of Copper Harbor Conglomerate, Portage Lake Volcanics, and Jacobsville Sandstone each provide accessible learning opportunities to both students and citizens and create spaces for deeper emotional connections to the landscape. Culturally and geologically important sites are currently used in both educational tools and to increase community-wide engagement in geologic studies (Cowling et al. 2023; Lizzadro-McPherson and Vye 2023). The principles of natural heritage, hereto referred also as ‘bioheritage’, strongly overlap with that of geoheritage. As geoheritage promotes connection to landscape via geological features, bioheritage facilitates connection through valuable natural features – ecosystems, flora and fauna – and encourages the conservation of landscapes that promote biodiversity. Sites that are identified by bioheritage ecologists, botanists, zoologists, and geographers as being of regional, scientific, or cultural significance often coincide with areas of high geodiversity. Categorization of these natural features show geographies dependent on both surface geology and glacial landforms; for example, the statewide distribution of volcanic bedrock lakeshore (Fig. 1), an imperiled natural community in Michigan, is wholly limited to surface-level exposures of Keweenawan rocks (Cohen et al. 2013) and supports a series of rare plants and animals found nowhere else in the state (Albert et al. 1997; MNFI 2026). Conservation of one outcrop for geological reasoning can therefore work beneficially for bioheritage, and vice versa. In the summer of 2025, we conducted interdisciplinary research highlighting the natural connections between underlying geological formations, community ecology, and rare plant Figure 1: Portage Lake Volcanics featured prominently along a high-quality volcanic bedrock lakeshore natural community recognized under both geoheritage and natural heritage. Figure 2: Pilot data examining ecological structure of bedrock lakeshore systems. Different zones of bedrock exposure promote plant communities of unique species composition. - 80 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 distributions on volcanic bedrock lakeshores of the Keweenaw Peninsula. The project involved collaboration between botanists, geologists, geographers, and conservationists. Pilot data yielded significant plant community differences between bedrock types and microhabitats, and the summer was documented in an educational StoryMap (Stone et al. 2025) (Fig. 2). Meandering transects outlining subtle distinctions in ecosystem processes based on geological formation identified multiple new rare plant populations, including the discovery of red anemone (Anemone multifida) on the Keweenaw Peninsula (Fig. 3). The project has since led to multiple additional collaborations in the Western Upper Peninsula focused on geoand bio-education. Partnerships between bioheritage and geoheritage scientists can be valuable sources of interdisciplinary research and collaboration. Despite originating in disparate academic fields, the two disciplines can work in tandem to increase scientific understanding of our geological features while producing valuable teaching tools. Future research and educational opportunities are plentiful as the two worlds of geoheritage and bioheritage establish common ground. REFERENCES Figure 3: Red anemone (Anemone multifida), a rare plant identified during field research on the Keweenaw Peninsula. Albert, D.A., Comer, P., Cuthrell, D., Hyde, D., MacKinnon, W., Penskar, M., & Rabe, M., 1997. The Great Lakes Bedrock Lakeshores of Michigan. Michigan Natural Features Inventory, Lansing, MI. 218 pp. Cohen, J.G., Kost, A., Slaughter, B.A., & Albert, D.A., 2015. A Field Guide to the Natural Communities of Michigan. Michigan State University Press. 362 pp. Cowling, R., Lizzadro-McPherson, D.J., Verissimo, L. & Vye, E.C., 2023. Keweenaw Geoheritage Geoatlas. DOI: 10.13140/RG.2.2.30945.28005 Lizzadro-McPherson, D. J. & Vye, E.C., 2023. Keweenaw Coastal Geoheritage Story Map. DOI: 10.13140/ RG.2.2.12680.74242 Michigan Natural Heritage Database (MNFI), 2026. Michigan Natural Heritage Database. Lansing, MI. Stone, A.F., Lizzadro-McPherson, D.J., and Vye, E.C., 2025. Rocks and Roots: A Keweenawan Love Story. StoryMap. https://storymaps.arcgis.com/stories/7d9a428effe04dc4923736310182d52f - 81 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Linking the Southwestern Laurentia large igneous province and rapid Duluth Complex emplacement through mantle plume dynamics SWANSON-HYSELL, Nicholas L.1, ZHANG, Yiming1, MOHR, Michael T.2, and SCHMITZ, Mark D.2 1 2 Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN, USA Department of Geosciences, Boise State University, Boise, ID, USA Midcontinent Rift volcanism was protracted, spanning from ca. 1109 to 1084 Ma with major magmatic pulses separated by ~10 Myr and >30° of latitudinal plate motion (Figure 1). The long duration of magmatism and large spatial displacement of the continent are difficult to reconcile with a single stationary mantle plume beneath the rift. A corresponding question is what caused the renewal of voluminous magmatism ca. 1096 Ma that produced the massive Duluth Complex layered mafic intrusions and comagmatic lavas of the North Shore Volcanic Group after a period of relative magmatic dormancy (Miller and Vervoort, 1996), and after Laurentia had drifted >3000 km since the rift’s initiation (Swanson-Hysell et al., 2019, 2021). Figure 1: The plate motion of Laurentia reconstructed from Midcontinent Rift paleomagnetic data revealing large-scale latitudinal change between the start of early phase volcanism and the major pulse of magmatism that emplaced the Duluth Complex ca. 1096 Ma. The red dot indicates the location of the Lake Superior region in each reconstruction. High-precision ²06Pb/²38U zircon dates developed through CA-ID-TIMS geochronology have resolved temporally distinct pulses of magmatism across Laurentia’s interior. In southwestern Laurentia, the Southwestern Laurentia large igneous province (SWLLIP) encompasses >750,000 km² of ca. 1.1 Ga mafic sills, dikes, and lava flows. New dates from SWLLIP mafic rocks reveal a rapid, voluminous magmatic pulse at ca. 1098 Ma, with thick sills emplaced across Death Valley, the Grand Canyon, and central Arizona within ≤0.25 Myr (Mohr et al., 2024). Approximately 2 Myr later, the bulk of the Duluth Complex anorthositic and layered series was emplaced ca. 1096 Ma in <1 Myr (500 ± 260 kyr; Swanson-Hysell et al., 2021). Both pulses were rapid and voluminous, characteristic of plume-related large igneous provinces. The close temporal and spatial relationship between the ca. 1098 Ma SWLLIP pulse and the ca. 1096 Ma Duluth Complex pulse supports a geodynamic link through lateral plume spreading. Rates of lateral plume spread predicted by mantle plume lubrication theory (Sleep, 1997) are consistent with a model in which a plume derived from the deep mantle impinged beneath southwestern Laurentia, then spread to the thinned Midcontinent Rift lithosphere over ~2 Myr, elevating mantle temperatures and generating melt. Buoyant plume material would have been directed to the rift through “upsidedown drainage” at the base of the Laurentian lithosphere (Sleep, 1997; Swanson-Hysell et al., 2021), - 82 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 wherein material flows along the topography of the lithosphere–asthenosphere boundary from thick to thin lithosphere. This hypothesis reconciles the close temporal relationships between voluminous magmatism across Laurentia and provides an explanation for the anomalous renewal of high magmatic flux within the protracted magmatic history of the Midcontinent Rift. REFERENCES Miller Jr., J.D., and Vervoort, J.D., 1996. The latent magmatic stage of the Midcontinent rift: a period of magmatic underplating and melting of the lower crust. In: Inst. Lake Superior Geol., 42nd Ann. Mtg., Proceedings, vol. 42, pp. 33–35. Mohr, M.T., Schmitz, M.D., Swanson-Hysell, N.L., Karlstrom, K.E., Macdonald, F.A., Holland, M.E., Zhang, Y., and Anderson, N.S., 2024. High-precision U-Pb geochronology links magmatism in the Southwestern Laurentia large igneous province and Midcontinent Rift. Geology, doi:10.1130/G51786.1. Sleep, N.H., 1997. Lateral flow and ponding of starting plume material. Journal of Geophysical Research, 102, 10,001– 10,012, doi:10.1029/97JB00551 Swanson-Hysell, N.L., Hoaglund, S.A., Crowley, J.L., Schmitz, M.D., Zhang, Y., and Miller, J.D., 2021. Rapid emplacement of massive Duluth Complex intrusions within the North American Midcontinent Rift. Geology, 49, doi:10.1130/ G47873.1. Swanson-Hysell, N.L., Ramezani, J., Fairchild, L.M., and Rose, I.R., 2019. Failed rifting and fast drifting: Midcontinent Rift development, Laurentia’s rapid motion and the driver of Grenvillian orogenesis. GSA Bulletin, 131(5–6), 913–940, doi:10.1130/B31944.1. - 83 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Deformation processes in a mid-crustal strike-slip shear zone: Insights from the Archean Quetico Shear Zone, Superior Province, Canada TIITTO, Hanna1, PHILLIPS, Noah1, 2, and STEPHAN, Tobias1 1 Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7C 5E1, Canada Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy., Los Angeles, CA, 90089-0740, United States 2 The brittle-ductile transition, where most earthquakes nucleate, occurs at ~10-15 km depth in the crust (Sibson, 1983). The structures produced at the brittle-ductile transition in active shear zones are challenging to study as they occur at depth. To further understand shear zone structures at depth, this study focuses on an analogue structure for active strike-slip systems, the Quetico Shear Zone, due to its estimated erosional depths of 10-15 kms, which exposes the Archean brittle-ductile transition zone (Percival et al., 2012). The Quetico Shear Zone is a right-lateral, strike-slip shear zone located within the Wabigoon and Quetico subprovinces and has a strike length of at least 400 km (Kennedy, 1984). This project focuses on the eastern extent of the shear zone, north of Thunder Bay, and aims to constrain the kinematics, structures, conditions, and timing of deformation processes within the shear zone and adjacent to paleo-earthquake surfaces. The extent of deformation from the shear zone was analyzed through macro- and microstructures using field mapping and microscopy. The conditions of deformation were constrained using paleopiezometry through electron backscattered diffraction of recrystallized quartz (Cross et al., 2017) and Ti-in-quartz geothermometry through secondary ion mass spectrometry measurements of recrystallized quartz (Wark and Watson, 2006). To constrain the timing of deformation, laser-ablation split-stream inductively coupled plasma mass spectrometry of apatite, monazite, titanite, and zircon was performed to produce U-Pb dates (Kylander-Clark, 2017). We found that Quetico Shear Zone deformation is characterized by increased mylonitization and brittle deformation with increasing proximity to the shear zone trace (within 500 m) where paleoearthquake surfaces (i.e., pseudotachylite veins) were found (Fig. 1). Mylonitization produces recrystallized quartz ribbons and a strong foliation unique to the Quetico Shear Zone (stronger than regional Quetico Subprovince transpressional structures), particularly in granitic units (Fig. 1C-E). Non-granitic rock units within the core of the shear zone display pervasive brittle deformation with numerous faults (Fig. 1A). Granitic rock types display more variable orientations due to the isolated quartz ribbons deforming around larger feldspar grains. The recrystallized quartz grain sizes do not correlate with increased mylonitization and proximity to the shear zone. Recrystallized quartz grain sizes remained constant within error, with calculated stress values ranging from 69 to 116 MPa, with a median of 80 MPa. The temperatures of quartz recrystallization range from 457 to 589°C, with a median of 487°C, with no clear evolution with increasing proximity to the Quetico Shear Zone trace. Apatite and titanite provided the best ages for deformation, mainly producing interpreted ages younger than the Quetico subprovince metamorphism. The interpreted Quetico Shear Zone deformation ages are approximately from 2620 to 2600 Ma. The exhumed Quetico Shear Zone appears to be deformed at a constant stress shortly after the Kenoran orogeny. REFERENCES Cross, A.J., Prior, D.J., Stipp, M., & Kidder, S., 2017. The recrystallized grain size piezometer for quartz: An EBSD-based calibration. Geophysical Research Letters, 44, 6667-6674. Kennedy, M.C., 1984. The Quetico Fault in the Superior Province of the Southern Canadian Sheild [MSc]: Lakehead University, 323. Kylander-Clark, A.R.C., 2017. Petrochronology Laser-Ablation Inductively Coupled Plasma Mass Spectrometry. Reviews in Mineralogy and Geochemistry, 83, 183-198. Percival, J.A., Skulski, T., Sanborn-Barrie, M., Stott, G.M., Leclair, A.D., Corkery, M.T., Boily, M., 2012. Geology and tectonic evolution of the Superior Province, Canada. Chapter 6 In Tectonic Styles in Canada: The Lithoprobe - 84 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Perspective. Geological Association of Canada, Special Paper 49, 321-378. Sibson, R.H., 1983. Continental fault structure and the shallow earthquake source. Journal of Geological Society, 140, 741767. Wark, D.A., and Watson, E.B., 2006. TitaniQ: a titanium-in-quartz geothermometer. Contributions to Mineralogy and Petrology, 152, 743-754. Figure 1: Quetico Shear Zone structures proximal to pseudotachylite veins: A: Plane-polarized light photomicrograph displaying pseudotachylite veins (medium brown layers cutting the white to light brown mylonitic fabric) from the core of the shear zone. Co-seismic injection veins are highlighted with white arrows. Right-lateral, late brittle faults are indicated by kinematic arrows. B: Magnified view of a pseudotachylite that has been viscously deformed. Cross-polarized light photomicrographs showing quartz microstructures of quartz-rich metamorphic rocks from increasing distance from the pseudotachylites: C: Extremely fine-grained quartz ribbons with minor feldspar porphyroclasts within a mylonite. D: Very fine-grained quartz within a quartz ribbon adjacent to fine-grained quartz in a protomylonitic granite. E: Fine- to mediumgrained recrystallized quartz within a weakly deformed granite. Note that the recrystallized grain size is consistent in C-E. - 85 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Variations in Olivine Major Element Composition Across the Midcontinent Rift System TOLLEY, James1 and HOLLINGS, Pete1 1 Department of Geology, Lakehead University, 955 Oliver Road, Thunder Bay, ON P7B 5E1, Canada. Olivine [(Mg,Fe)2SiO4] is an early crystallising phase in mafic–ultramafic Ni–Cu–(PGE) deposits and a sensitive recorder of mantle melting history. Its forsterite content reflects the parental melt composition, while the Ni concentration and trace element ratios can be used to constrain petrogenetic processes and the physicochemical conditions of melting. However, the plutonic nature of these deposits means primary compositions can be overprinted by sub-solidus re-equilibration and latestage fluid interaction, complicating the recovery of primary magmatic signals. Deconvoluting these signatures is critical to understanding melt generation, fractionation, and ultimately the mineralisation processes that govern the formation of these deposits. The Midcontinent Rift System (MRS) one of the most extensively mineralised large igneous provinces and renowned for its magmatic Ni–Cu–(PGE) deposits. Despite this, olivine compositional data is sparse. We present new and collated major element olivine data from multiple Ni–Cu–(PGE) deposits across the MRS to evaluate regional-scale trends in forsterite and Ni contents. We examine deposit-scale variability and explore broader implications for the underlying magmatic architecture of the rift system. This study builds on previously collected electron probe microanalyses (EPMA) of olivine from mineralised magmatic Ni–Cu–(PGE) deposits of the MRS within Canada e.g., Sunday Lake (Durán, 2025), Steepledge (Harding, 2024), Escape Lake, Current and Hele, and contributes new olivine compositional data from several unmineralized intrusions, namely Inspiration Sill, St. Ignace Island and Nipigon Sills. These data are further supplemented by olivine compositions from USA-based mineralised Ni–Cu deposits e.g., Tamarack (Goldner, 2011; Taranovic, 2015) and the Duluth Complex (Peterson, 2025). Together, this data constitutes the first regional-scale compilation of olivine chemistry across the MRS. Figure 1: Simplified geological map of the Midcontinent Rift System highlighting the distribution of major rock types. Locations of the mafic–ultramafic intrusions sampled in this study are denoted by stars (red = data collected in this study; blue = literature data). Modified after: Good et al. (2015). - 86 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 REFERENCES Ding, X., Li, C., Ripley, E. M., Rossell, D., & Kamo, S. (2010). The Eagle and East Eagle sulfide ore‐bearing maficultramafic intrusions in the Midcontinent Rift System, upper Michigan: Geochronology and petrologic evolution. Geochemistry, Geophysics, Geosystems, 11(3). Durán, K. M. (2025), Petrogenesis of the Sunday Lake Intrusion, Jacques Township, Ontario, Canada. M.Sc. thesis Lakehead University, Thunder Bay, Ontario, 222p. Goldner, B.D. (2011). Igneous petrology of the Ni–Cu–PGE mineralized Tamarack intrusion, Aitkin and Carlton Counties, Minnesota; M.Sc. thesis, University of Minnesota, Minneapolis, 156p. Good, D.J. (1992). Genesis of copper-precious metal sulphide deposits in the Port Coldwell Alkalic Complex, Ontario; unpublished Ph.D. thesis, McMaster University, Hamilton, Ontario, 203p. Good, D. J., Epstein, R., McLean, K., Linnen, R. L. and Samson, I. M. (2015). Evolution of the Main Zone at the Marathon Cu–PGE sulfide deposit, Midcontinent Rift, Canada: Spatial relationships in a magma conduit setting. Economic Geology, 110(4), 983–1008p. Harding, M. F., (2024). Olivine Geochemistry of the Current and Escape Lake (Steepledge) intrusions, Thunder Bay North Intrusive Complex. HBSc. Thesis, Lakehead University, Thunder Bay Ontario. Heggie, G.J. (2005). Whole rock geochemistry, mineral chemistry, petrology and Pt, Pd mineralization of the Seagull Intrusion, northwestern Ontario. M.Sc. thesis, Lakehead University, Thunder Bay, Ontario, 156p. Peterson, D.M., (2025). Compilation of electron probe microanalyses of Olivine from the Duluth Complex, Minnesota, USA [Unpublished Dataset – personal communication]. Shaw, C. S. (1997). The petrology of the layered gabbro intrusion, eastern gabbro, Coldwell alkaline complex, Northwestern Ontario, Canada: evidence for multiple phases of intrusion in a ring dyke. Lithos. 40(2-4), 243–259. Taranovic, V., Ripley, E.M., Li, C. and Rossell, D., (2015). Petrogenesis of the Ni–Cu–PGE sulfide-bearing Tamarack Intrusive Complex, Midcontinent Rift System, Minnesota. Lithos, 212, 16–31p. - 87 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 Index AKIN, Kathryn�����������������������������������������������������1 ALLERTON, Zsuzsanna���������������������������������3, 31 AMES, Carsyn����������������������������������������������������78 ANGOMBE, Moses����������������������������������������5, 69 BAIN, Wyatt���������������������������������������������������������6 BEDROSIAN, Paul A.����������������������������������������16 BEYER, Steve�������������������������������������������������������8 BILBOE, Michael�����������������������������������������������10 BLEEKER, Wouter���������������������������������������������12 BONAMICI, Chloë���������������������������������������������41 BORNHORST, Theodore�����������������������������������21 BOUCHER, Chanelle�����������������������������������������61 BRENGMAN, Latisha����������������������������25, 29, 51 BUCHHOLZ, Thomas����������������������������������������14 CAMACHO, Alfredo��������������������������������������������8 CANNON, W. F.�������������������������������������������16, 67 CARLTON, Kenz M.������������������������������������������18 CAWOOD, Tarryn������������������������������������������������8 CHAISSON, Amy�����������������������������������������������19 CHASE, Pete������������������������������������������������������78 CHITTICK, Steve�����������������������������������������������65 CHURCHLEY, Jeffrey����������������������������������������73 CISNEROS, John Alex���������������������������������������29 CONLY, Andrew�������������������������������������������������10 COOKE, David���������������������������������������������������45 COWLING, Bob�������������������������������������������������21 CUTTS, Jamie�������������������������������������������������������8 DEERING, Chad�������������������������������������������������55 DeGRAFF, James�����������������������������������������21, 48 DELLER, Matt������������������������������������������������5, 69 DOLEGA, Simon������������������������������������������������73 DRENTH, Benjiman J.���������������������������������������16 DREVER, Garth���������������������������������������������������8 DROST, Abraham�����������������������������������������������23 DROUBI, Omar��������������������������������������������������41 DUFFY, Paige�����������������������������������������������������25 EASTON, Robert Michael����������������������������������27 ELLISON, Kimberly�������������������������������������������29 ENKIN, Randy����������������������������������������������������71 ERICKSON, Stephanie���������������������������������������31 ESSIG, Espree�����������������������������������������������������55 EYSTER, Athena������������������������������������25, 29, 51 FALSTER, Alexander�����������������������������������������14 FAYON, Annia����������������������������������������������������31 FEINBERG, Josh������������������������������������������������75 FLANK, Steven��������������������������������������������������73 FRALICK, Philip������������������������������������������33, 34 GAMET, Nolan���������������������������������������������������63 GAONA, Jorge Mario�����������������������������������������53 GILBERG, Nolan�����������������������������������������������33 GORNER, Emily������������������������������������������������45 GOSAI, Meghna�������������������������������������������������34 GRAHAM, G.�����������������������������������������������������78 GRAUCH, V.J.S��������������������������������������������������35 HAGEDORN, Grant�������������������������������������������37 HAKURTA, Joyashish����������������������������������������59 HAMILTON, Mike���������������������������������������������50 HAMMER, Mikala���������������������������������������������75 HARDING, Myles����������������������������������������������39 HART, Dave��������������������������������������������������������78 HASTIE, Evan����������������������������������������������������50 HEGGIE, Geoff��������������������������������������������������23 HELLER, Samuel J.��������������������������������������������35 HELLRUNG, Alyssa������������������������������������������41 HILLENBRAND, I.��������������������������������������������67 HILLIPS, Noah���������������������������������������������������84 HILTUNEN, Lindsay������������������������������������������21 HIRSCH, Aaron��������������������������������������������������43 HODGE, Joanna�������������������������������������������������74 HOLLINGS, Pete����������������5, 6, 39, 45, 69, 77, 86 HOMPSON, J. M������������������������������������������������67 HUDAK, George��������������������������������������������3, 31 JONSSON, Justin������������������������������������������������47 KAMO, Sandra���������������������������������������������27, 50 KASKI, Krista�����������������������������������������������������71 LAFRENIERE, Don�������������������������������������������21 LI, Zhiquan���������������������������������������������33, 34, 47 LIZZADRO-McPHERSON, Dan�����������21, 48, 80 MACDONALD, Peter����������������������������������������50 MAHIN, Robert��������������������������������������������������63 MALEGUS, Paul������������������������������������������������50 MANGUM, John������������������������������������������������51 MARIN LÓPEZ, Valentina���������������������������������51 MARSH, Jeff������������������������������������������������������50 McNALL, Natalie�����������������������������������������������78 MITCHELL, Jennifer�����������������������������������������51 MOHR, Michael�������������������������������������������������82 NACHLAS, William O���������������������������������������18 NESHEIM, Timothy�������������������������������������������65 NITESCU, Bogdan���������������������������������������������53 NOWAK, Robert�������������������������������������������������55 NOWARIAK, Eric����������������������������������������������57 OST, Sara������������������������������������������������������������59 PALIEWICZ, Cory���������������������������������������������59 - 88 - �Proceedings of the 72nd ILSG Annual Meeting - Part 1 PETERSON, Dean����������������������������������������������61 PHILLIPS, Noah���������������������������������������������5, 77 POWELL, Jeremy�������������������������������������������������8 PU, Xiaofei���������������������������������������������������������51 QUIGLEY, Ashley����������������������������������������������63 RILEY, Jack��������������������������������������������������������75 ROBILLARD, Carly�������������������������������������������74 ROSE, William���������������������������������������������21, 48 RUGGLES, Claire����������������������������������������������41 SAINI-EIDUKAT, Bernhardt�����������������������������65 SALERNO, R�����������������������������������������������16, 67 SANDRI, Henry��������������������������������������������������75 SAVAGE, Brian��������������������������������������������������75 SCHMITZ, Mark������������������������������������������������82 SEVERSON, Allison������������������������������������������57 SHESHNEV, Vlad������������������������������������������5, 69 SIMMONS, William�������������������������������������������14 SMITH, Andrew���������������������������������������������������5 SMITH, Jennifer�������������������������������������������������71 SMYK, Emily�����������������������������������������������������73 SMYK, Mark������������������������������������������������19, 74 SOUDERS, A. K�������������������������������������������������67 STEINER, R. Alex����������������������������������������61, 75 STEPHAN, Tobias������������������������������������5, 77, 84 STERN, Richard�������������������������������������������������69 STEWART, Eric��������������������������������������������������78 STEWART, Esther����������������������������������������������78 STONE, Abraham�����������������������������������������������80 SWANSON-HYSELL, Nicholas��������������������1, 82 SWEET, Gabriel�������������������������������������������������61 THOLE, Jeff�������������������������������������������������������75 TIITTO, Hanna���������������������������������������������������84 TIKOFF, Basil�����������������������������������������������������18 TOLLEY, James��������������������������������������������69, 86 TORRES, David Santiago����������������������������������53 TSCHIRHART, Victoria�������������������������������������71 VERVOORT J.����������������������������������������������������67 VRZOVSKI, Joseph�������������������������������������������45 VYE, Erika����������������������������������������������21, 48, 80 WALKER, Patrick�����������������������������������������������51 WATSON, Noa����������������������������������������������������75 WODICKA, Natasha������������������������������������������12 ZHANG, Yiming�������������������������������������������������82 ZUREVINSKI, Shannon�������������������������������10, 19 - 89 - � https://digitalcollections.lakeheadu.ca/files/original/9c27d09e8827f7b36e6389fd03c441fd.pdf ed3efa960579e362e6c602cd6bb9be41 PDF Text Text 72nd Annual Meeting Thunder Bay, Ontario - May 21-22, 2026 Institute on Lake Superior Geology Part 2 – Field Trip Guidebook �Thank you to our sponsors! �72tnd Annual Meeting Institute on Lake Superior Geology May 21-22, 2026 Thunder Bay, Ontario HOSTED BY: Mark Puumala and Peter Hinz Co-Chairs Ontario Geological Survey (Retired) Proceedings - Volume 72 Part 2 – Field Trip Guidebook Compiled and edited by Pete Hollings Cover Photos: Top - Keweenawan diabase dyke on Lake Superior shoreline near Thunder Bay, Middle Archean-Paleoproterozoic unconformity, Highway 11-17, near Pass Lake turnoff, Bottom - Colloform stromatolite, Gunflint Formation, Kakabeka Falls �72nd Institute on Lake Superior Geology Volume 72 consists of: Part 1: Program and Abstracts Part 2: Field Trip Guidebook Trips 1 & 4: “Classic” Geological Sites in the Thunder Bay Area Trip 2: Geology of the Quetico Supprovince North of Thunder Bay Trip 3: Gold Deposits of the Shebandowan Greenstone Belt Trip 5: Structural Geology and Gold Mineralisation of the Mine Centre Area Trip 6: Amethyst Deposits of Thunder Bay Reference to material in Part 2 should follow the example below: Poulsen, K.H., 2026. Archean Geology and Metallogeny of the Rainy Lake Wrench Zone. In; Hollings, P. (Ed.), Institute on Lake Superior Geology Proceedings, 72nd Annual Meeting, Thunder Bay, Ontario, Part 2 Field trip guidebook, v.72, part 2, 3-31. Published by the 72nd Institute on Lake Superior Geology and distributed by the ILSG Secretary: Pete Hollings - ILSG Secretary Department of Geology Lakehead University 955 Oliver Road Thunder Bay, ON P7B 5E1 Canada Email: peter.hollings@lakeheadu.ca ILSG website: www.lakesuperiorgeology.org ISSN 1042-9964 �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Table of Contents Introduction - considerations and acknowledgements.........................................................1 Trips 1 & 4 - “Classic” Geological Sites in the Thunder Bay Area.....................................2 Trip 2 - Geology of the Quetico Subprovince and Shebandowan greenstone belt north of Thunder Bay...............................................................................................................44 Trip 3 - Geological assemblages, regional structural framework and tectonic evolution of the Neoarchean Shebandowan greenstone belt..........................................................67 Trip 5 - Archean Geology and Metallogeny of the Rainy Lake Wrench Zone..................82 Trip 6 - Amethyst Deposits of Thunder Bay....................................................................126 -i- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Introduction - considerations and acknowledgements Peter Hinz and Mark Puumala Resident Geologist Program, Ontario Geological Survey, Ministry of Energy & Mines, Thunder Bay, Ontario (Retired) This volume is intended to serve not only as a guide for the 72nd ILSG field trip participants but also as a reference for those interested in reprising the trips at a future date. In order to facilitate this, trip leaders have provided UTM coordinates in the NAD 83 datum for stops, as well as plain word descriptions for locating each trip stop. It should be noted that some stops are located on private land or registered mining claims. As such, individuals visiting these stops are advised to obtain the land holders’ permission prior to entering their property. If in doubt, we recommend contacting the Resident Geologist Program office in Thunder Bay for further information about current property ownership. This year’s slate of field trips include stops located either on provincial highways or busy logging roads which can create safety issues. For those participating in facilitated trips at this year’s meeting, make sure to pay attention to the trip leaders’ safety orientation at the start of the trip, and follow any stop-specific safety instructions. For individuals using the field trip guide for future private tours it is advisable to be wary of road traffic and exercise extreme caution. Please take care when crossing or parking at the sides of these roads. The organizing committee would like to thank all the field trip leaders who authored and contributed to this field guide along with those who provided comments and/or assisted with the running of the trips themselves. Field trip leaders and authors include Howard Poulsen, Riku Metsaranta, Gaetan Launay, Dorothy Campbell, Justin Jonsson, Vittoria D’Angelo, Mark Smyk, Mark Puumala, Steve Kissin and Greg Paju. The Committee thanks participating exploration companies and mine operators for their cooperation and assistance in providing access and information in regards to their properties, as well as their staff time for leading the tour participants on their respective properties. Participating companies include Delta Resources, Gold X2 Mining, Amethyst Mine Panorama and Diamond Willow Amethyst Mine. Figure 1. Map illustrating general locations of ILSG 2026 field trips. Symbols are labelled with numbers that correspond to the trip numbers (1 to 6) used in the meeting program and field trip guidebook. -1- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Trips 1 & 4 - “Classic” Geological Sites in the Thunder Bay Area Mark Smyk Department of Geology, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada and Mark Puumala Geological Consultant, 370 Crossbow Court, Thunder Bay, Ontario, P7G 1H5 Canada Introduction The geology of the Thunder Bay area features a variety of Archean and Proterozoic rocks of the Superior and Southern Provinces of the Canadian Shield, respectively, as well as unconsolidated deposits and landforms associated with Quaternary glacial and post-glacial processes. This field trip features examples of many of these rocks and features, providing an overview of the varied geology the area has to offer. A number of field guides (e.g., Pye, 1969; Kustra et al., 1977; Franklin et al., 1982) have covered the Thunder Bay area, including those written for the 46th (e.g. Pufahl et al., 2000; Phillips et al., 2000) and 58th Institute on Lake Superior Geology annual meetings (e.g. Fralick et al., 2012; Smyk, 2012; Phillips et al., 2012; Cundari et al., 2012). These guides contain descriptions of some of the field trip stops covered in this guide and they will be referenced appropriately. This guide also benefits from ongoing local research and mapping conducted by the Ontario Geological Survey, Geological Survey of Canada and Lakehead University. Day One of this trip features exposures north and east of Thunder Bay, while those of Day Two are located south and west of the City. Bear in mind that this trip marks the first time that many of these stops have been visited and described as part of a formal field trip. This is especially true of stops along Highway 11-17, whose expansion ca. 2010-2012 produced many remarkable new exposures. Please exercise caution when stopping and viewing roadside outcrops. Permission or admittance may need to be obtained to visit some stops; this will be outlined in the guide when necessary. Regional Geology Overview Precambrian Geology The Thunder Bay area straddles the boundary between Archean rocks of the Superior Province and Proterozoic rocks of the Southern Province (Figure 1). In the vicinity of Thunder Bay, Superior Province rocks comprise volcano-plutonic rocks of the Neoarchean Wawa Subprovince and metasedimentary and granitoid rocks of the Neoarchean Quetico Subprovince, bounding the Wawa to the north. Locally, the supracrustal rocks of the Wawa Subprovince have been subdivided into the Greenwater and Shebandowan assemblages (Williams et al., 1991). The ca. 2.72 Ga Greenwater assemblage consists of a north-younging sequence of mafic to felsic metavolcanic rocks with subordinate interbedded clastic and chemical metasedimentary rocks. Mafic metavolcanic rocks within this assemblage consist predominantly of tholeiitic to calc-alkalic pillowed flows. The intermediate and felsic metavolcanic sequences are calc-alkalic and consist predominantly of coarse-grained pyroclastic deposits and massive to feldspar-phyric flows. The ca. 2.69 Ga Shebandowan assemblage is a younger, possibly fault-bounded (Williams et al., 1991) sequence of sub-alkalic to alkalic, predominantly coarse-grained pyroclastic metavolcanic rocks with interbedded coarse- to fine-grained, commonly well-preserved, proximal metasedimentary rocks. Intrusions within the Wawa Subprovince supracrustal assemblages consist of narrow felsic dikes, syenitic to tonalitic pre- to syntectonic plutons, minor gabbro bodies and scattered narrow mafic dikes. Rocks of the Neoarchean Quetico Subprovince abut the Wawa Subprovince to the north. They consist mainly of clastic metsedimentary rocks (turbiditic wacke, arkose, quartz arenite, slate and argillite) as well as post- to syn-deformational, syenitoid to granitoid plutons (cf. Metsaranta, 2022; Metsaranta and Walker, 2019). Migmatization becomes common in the rocks towards the northern portion of the area as metamorphic grade increases (Williams, 1991). -2- The Southern Province consists of Proterozoic �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 1. Generalized geology of the Thunder Bay area; geology from Ontario Geological Survey Map 2542, Bedrock Geology of Ontario, West-Central Sheet, scale 1:1 000 000 (1991). rocks which unconformably overlie or intrude Archean basement rocks of the southern Superior Province (cf. Tanton, 1931; Pye, 1969). North and west of Lake Superior, the Southern Province comprises: 1) Paleoproterozoic (ca. 1.8 Ga) Animikie Group sedimentary and minor volcanic rocks; 2) Mesoproterozoic (ca. 1.4 Ga) Sibley Group sedimentary rocks; and -3- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 3) Mesoproterozoic (ca. 1.1 Ga) Midcontinent Rift volcanic and intrusive rocks. The Animikie Group, exposed in Ontario, Minnesota, Wisconsin and Michigan, is represented locally by the Gunflint Formation and overlying Rove Formation. These dominantly sedimentary formations constitute a largely unmetamorphosed, undeformed, homoclinal succession which dips shallowly to the southeast. The Gunflint Formation is a chemicalclastic assemblage which yielded a U-Pb age from reworked volcanic ash of 1878.3 ± 1.3 Ma (Fralick et al., 2002). Rocks containing intraformational breccias, accretionary lapilli, spherules and shocked quartz that occur near the top of the Gunflint Formation are interpreted to represent ejecta from the Sudbury impact event that occurred at circa 1850 Ma (Addison et al., 2005; Krogh, Davis and Corfu 1984). The Gunflint Formation grades upward into turbiditic sandstone and shales of the Rove Formation south of Thunder Bay. U-Pb zircon ages from ash beds in the basal Rove Formation yielded 1836+5 and 1832+3 Ma (Addison et al., 2005). A sandstone sample from the submarine fan portion of this succession yielded a youngest detrital zircon U-Pb age of approximately 1780 Ma (Heaman and Easton, 2006), but this relatively young age is widely considered to be problematic and not reflective of the true age of these rocks. Sedimentation in this part of the Animikie basin, widely thought to represent the distal foreland of the Penokean Orogen, likely ended ca. 1800 Ma or earlier. However, Maric (2006) suggested that the Rove (and correlative Virginia) Formation represents the transition from a sedimentstarved basin, with exceedingly slow deposition rates, to active deltaic progradation with sediment probably derived from the Trans-Hudson orogenic zone to the north. The Sibley Group, exposed on the Sibley Peninsula and farther north, has been subdivided into five formations; detailed descriptions of each formation have been reported previously (Franklin et al., 1980; Cheadle, 1986; Rogala, 2003; Rogala et al., 2005, 2007). The overall sedimentary environment indicates a fluctuating climatic scenario, in which the Sibley Group was deposited in a lacustrine system (Pass Lake Formation) that gradually evolved into a saline playa lake environment (Rossport Formation). As the climate progressively became drier, a sabkha-type environment developed (Fire Hill Member of the Rossport Formation). After a break in time, the Kama Hill and Outan Island formations represent outbuilding of a large deltaic complex to the north (Jones et al., 2022), and the Nipigon Bay Formation represents an aeolian environment (Rogala, 2003; Rogala et al., 2007). The depositional age for much of the Sibley Group had been constrained between ~1340 and 1450 Ma. The northern margin of the Midcontinent Rift is dominated by mafic hypabyssal rocks of the Midcontinent Rift Intrusive Supersuite (Miller et al. 2002), which intrude all Proterozoic rocks and Archean basement. South of Thunder Bay, Logan (1106.3+2.0 Ma; Smith et al., 2025) diabase sills predominate. Nipigon diabase sills (1108.2+0.9 Ma; Bleeker et al., 2020) occur in and north of the City, and form the bulk of the Nipigon Embayment. Volcanic and minor sedimentary rocks of the ca. 1108 to 1105 Ma Osler Group (Davis and Sutcliffe, 1985; Davis and Green, 1997) are exposed to the east on Black Bay Peninsula and on offshore islands in Lake Superior. While all aforementioned rocks are related to the Early Magmatic Stage (ca. 1110–1103 Ma; Miller and Nicholson, 2013) of Midcontinent Rift development, younger intrusions (ca. 1097-1092 Ma; Smith et al., 2025) are associated with a magmatic episode that followed the emplacement of the 1099 Ma Duluth Complex. Three main domains were suggested by Smith et al. (2025) in describing the northern flank of the Midcontinent Rift west of Thunder Bay and Lake Nipigon, namely, from south to north: (1) a gently south-(southeast-)tilted Midcontinent Rift margin; (2) a pronounced basement arch just north of Thunder Bay, likely representing a flexural bulge; and (3) the erosional remnant of the Lake Nipigon rift-and-sag basin, preserving the Sibley Group intruded by extensive Nipigon diabase sills (Figure 2). Quaternary Geology The first Pleistocene ice sheet in the Thunder Bay region, ca. 1 Ma, moved over and stripped a deeply weathered, relatively flat bedrock landscape (Zaniewski et al., 2020). During the Pleistocene, possibly ten or more major advances and retreats of ice took place, each with its own history of advancing and retreating lobes of ice. The region’s present landscape is the product of interplay between three major ice lobes (i.e. Patricia or Rainy River Lobe, from the north; the Hudson Bay Lobe, from the northeast; and the Superior Lobe, from the east) originating from three accumulation centers -4- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 2. West-looking cross section through the northern flank of the Midcontinent Rift, just west of Thunder Bay and Lake Nipigon, from Smith et al. (2025) during Wisconsin glaciation. Only the final event, comprising the Marquette Readvance (ca. 11 500 Ka) and its subsequent retreat, is understood in local detail (ibid). remains of the toolkit of these people other than a variety of knapped lithic tools made from taconitic chert that occurs in the local Gunflint Formation (cf. Hamilton, 1996). Starting about 11,000 years ago (Ka), Wisconsin ice melted back from its position in central Minnesota and Wisconsin, and quickly exhumed the Thunder Bay region, forming recessional moraines during brief stillstand periods (Phillips, 2004; Phillips et al., 1994). The Lake Superior basin was occupied by Early Lake Minong, the shoreline of which is found close to the 1400-foot (427m) contour in the borderland area. About 10 Ka, ice re-advanced from north of Lake Nipigon, sweeping across the Superior Basin (Marquette Readvance). As that ice began to melt, glacial lakes were formed between the moraines and the retreating ice margins. As Superior ice melted, water levels progressively lowered, forming a series of shoreline features down-slope and depositing thick lacustrine clays. Superior ice withdrew to the north of Lake Nipigon around 9.5 Ka, and for the first time since the Marquette Re-advance, the Superior basin was occupied by a single lake, Lake Minong. This lake level extended up the Kaministiquia embayment to Rosslyn, where a large delta structure was built. The Minong shoreline runs through the upper part of the city, being particularly evident in Boulevard Park where river mouth bars and terraces of the Current River are seen. The Minong shoreline in the city is strongly associated with Palaeo-Indian sites, the Cummins Site being the best-known. It is likely that as water levels fell, these early people moved down from the Arrow-Whitefish Lakes area into the Kaministiquia embayment. Little Field Trip Stop Descriptions - Day One Day One begins with visits to a number of locations northeast of the City, clustered around the northern end of Thunder Bay of Lake Superior (Figure 3) and ends near and within the City (Figure 4). This small area is underlain by a variety of rocks that record almost three billion years of local geologic history, spanning from the Neoarchean (ca. 2.7 Ga) to the Paleoproterozoic (ca. 1.8 Ga) and Mesoproterozoic (ca. 1.4 and 1.1 Ga) and perhaps to the Mesozoic (ca. 100 Ma). Unconsolidated glacial and post-glacial deposits and features attest to a long-lived, Pleistocene glaciation record. All GPS coordinates are NAD83, UTM Zone 16. STOP 1-1: Blende Lake Unconformity (0367703 E / 5383357N) This exceptional highway rock cut, like many others on this stretch of Highway 11-17, was exposed by new highway excavations ca. 2012. This ~700 m-long exposure features the unconformity between Neoarchean Wawa metavolcanic and gabbroic rocks and Paleoproterozoic sedimentary rocks of the lower Gunflint Formation (cf. Scott, 1990; Figure 5). Basement rocks here have also been described by Landman (2021) as coarse-grained amphibolite, interpreted as a mafic intrusion which has undergone amphibolite-facies metamorphism. -5- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 3. Generalized geology of the northern end of Thunder Bay of Lake Superior, showing the first 9 field trip stop locations of Day 1. Geology from Map M2232 (Carter et al., 1973). BLF – Blende Lake Fault This exposure was described by Metsaranta and Kurcinka (2022), as part of an ongoing Ontario Geological Survey (OGS) bedrock mapping project of the Animikie Basin near Thunder Bay: “…chloritized Archean felsic to intermediate intrusive rocks are locally overlain by at least 4 stromatolite mounds comprising thinly laminated black to red chert [Figure 6]. The stromatolite mounds have a height of up to 30 to 50 cm and similar widths. The top of one mound is marked by a thin stylolitic band [Figure 7]. The areas between stromatolite mounds comprise silicified grainstones that locally contain sulphide nodules up to 5 cm in diameter. The grainstones enclosing the stromatolite form medium to thick beds characterized by medium- to large-scale trough cross-stratification. At this locality, an east-dipping and roughly north-striking small displacement thrust fault puts Archean basement rocks above Gunflint Formation rocks. The fault appears to displace Midcontinent Rift–related quartz-carbonate-sulphide veins indicating Figure 4. Field trip stop location map, showing Day 1 stops 1-10 and 1-11 and Day Two stops. (See Figure 3 for map legend). -6- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 5. Paleoproterozoic Gunflint Formation sedimentary rocks unconformably overlying Archean basement, east side of Highway 11-17, STOP 1-1. that the thrusts may be related to rift inversion; however, this field relationship is equivocal.” These ferroan dolomite and siderite grainstones (medium-grained, sand-sized iron carbonates), referred to as granular iron formation, are common in the Thunder Bay region, dominating the near-shore of the Animikie Basin (see Fralick et al., 2012; STOP 1-4). The thin basal conglomerate (aka Kakabeka Member, Figure 8) of the Gunflint Formation is discontinuously distributed along the paleosurface. As described by Metsaranta and Kurcinka (2022), the conglomerate has a clast-supported texture, consisting of coarse-grained sand, granules, pebbles and rare cobbles in a sandy matrix. Quartz, pink granitoid, clastic metasedimentary and mafic metavolcanic clasts were noted. Figure 6. Mound-shaped stromatolites, with onlapping grainstones, resting on chloritized Archean basement, STOP 1-1. The stromatolite has a black chert core, and red, jaspilitic outer layers. Photo from Metsaranta and Kurcinka (2022). varies from 0 to 30 cm in thickness here, and is usually absent from the local topographic “highs” (i.e. knobs or ridges of the Archean basement), but may thicken in depressions in the paleosurface. The basal conglomerate lag may contain large, well-rounded boulders, up to 0.5 m in diameter; these have been observed only on the northwest side of the highway, opposite STOP 1-1. Black, cherty bands (0.1–1.5 cm) occur locally in parts of the Kakabeka conglomerate (ibid). Recent geochronologic study of the conglomerate shows that the main population of detrital zircons is consistent with derivation from local Neoarchean intrusions (R. Kup et al. (2025) also noted that the conglomerate Figure 7. Stylolites in Gunflint Formation grainstone, STOP 1-1, visible as a black serrated band to the right of the scale card. Figure 8: Quartz pebble-rich Kakabeka conglomerate, STOP 1-1. Photo from Metsaranta and Kurcinka (2022). -7- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Metsaranta, personal communication, 2026) like the Mackenzie granite (ca. 2672 Ma; Puumala et al., 2015). The stromatolites which occur in the basal unit of this Gunflint section (Unit 1 of Kup et al., 2025) were described by Kup et al. (2025): “Unit 1 of the Gunflint Formation is characterized by the common occurrence of cherty, domical to columnar stromatolites within the basal 2 m of the formation. Relatively large stromatolite heads tend to occur preferentially on knobs or ridges of the Archean basement, usually metres apart from one another. Smaller stromatolite heads (5–15 cm in diameter or height) are present locally, even on top of the Kakabeka conglomerate. Tabular, finely undulatory, microbialite-like structures (commonly <10 cm thick) may occur in places, or laterally connected to stromatolite heads. The microbialite-like structures may weather to a reddish colour, similar to some of the weathered stromatolite heads. Overall, the colour of the domical to columnar cherty stromatolites ranges from red, yellow, white, grey and black, depending on the iron content and the nature of weathering. Relatively large (usually fresh) stromatolite heads tend to be jet black near their centre and change to lighter grey and white toward their edges; however, edges themselves are commonly marked by red and/or yellow banding. The stromatolites are most easily seen and accessible toward the southern ends of the outcrop, directly above the road ditch level.” galena, have been noted. The fault is also exposed on the other side of the highway; Gunflint rocks are folded next to the fault there as well. The east-northeast orientation of the Blende Lake Fault is similar to other structures on and north of the Sibley Peninsula, some of which host gabbroic dykes Figure 9. Rock cut exposure of the Blende Lake Fault, east side of Highway 11-17 (STOP 1-2), separating folded Gunflint Formation rocks (left) from Neoarchean basement (right). The fault zone is cored by calcite vein / vein breccia; fault gouge flanks the vein. Field notebook for scale. Optical and SEM imaging data collected by Kup et al. (2025) suggest that well-preserved Gunflint-type microfossils (both filamentous and coccoid types) tend to occur in sporadic pockets in samples collected from this locality. attributed to the waning stages of Mesoproterozoic Midcontinent Rift magmatism. Scott (1990) noted that Gunflint rocks, normally flat-lying or gently southeastdipping, are folded and brecciated to a large extent in the area between Blende Lake and O’Connor Point on Lake Superior. Folding described by Moorhouse (1960) east of Blende Lake, was attributed to farfield Penokean fold-and-thrust deformation by Hill and Smyk (2005), prior to the recognition of the Sudbury Impact Layer and associated deformation in the Animikie Basin. Koroscil (2013) noted that thrust faults, once ascribed to Penokean deformation, cut the SIL at the Terry Fox Monument (STOP 1-10) and thus may post-date the Penokean. Landman (2021) noted that: STOP 1-2: Blende Lake Fault (0368005 E / 5383802N) The northern end of the same rock cut, approximately 500 m north-northeast of STOP 1-1, exposes the eastnortheast-striking Blende Lake Fault (cf. Scott, 1990). Rusty fault gouge occurs between Archean gabbroic rocks to the south and folded, flaser-bedded Gunflint wacke and siltstone, cored by a 3 m-wide calcite + quartz vein / vein breccia which contains Gunflint fragments (Figure 9). Base metal sulphides, including -8- “Later Proterozoic features, including the Blende Lake fault, have a common strike of eastnortheast, which aligns with the orientation of the 1.1 Ga Mid-Continent Rift in Thunder Bay. This similarity is further reflected by the Blende Lake fault being oriented subparallel to silver veins related to the Mid-Continent Rift. Similarities between orientations of brittle structures in the [Neoarchean] amphibolite and Gunflint Formation suggest that the Mid-Continent Rift �Proceedings of the 72nd ILSG Annual Meeting - Part 2 in Thunder Bay may have reactivated some Archean-aged, orogenic-related faults and shear fractures. Minor folding in the Gunflint Formation truncated by the Blende Lake fault, as well as reverse reactivation along the plane, may be evidence of compression during the later stage of the Mid-Continent Rift.” STOP 1-3: Mirror Lake Turn-off (0370744 E / 5387262N) This stop displays a number of quite enigmatic features that are still being evaluated in the context of evolving local geologic ideas. The hillside exposes iron-rich, folded and brecciated Gunflint Formation sedimentary rocks that have been intruded by a Nipigon diabase sill. Tight to isoclinal, plunging to recumbent folds have developed in certain parts of the otherwise ~flat-lying, thinly to thickly bedded, taconitic, martite(?)-bearing grainstones (Figure 10). As is the case at STOP 1-2, the cause of the deformation in the Gunflint rocks is a matter of debate. There is growing support that local folding and brecciation may be related to far-field effects generated by the Sudbury meteor impact ca. 1850 Ma., postdating the end of Gunflint deposition by perhaps ca. 20 My and preceding the onset of Rove sedimentation. Rocks interpreted as being part of the Sudbury Impact Layer were noted in geotechnical drilling ~ 1 km north of this location (P. Fralick, personal communication, 2025). Despite the fact that the Sudbury impact structure is ~660 km away and that the most dramatic deformation is usually crater-proximal (i.e. within ~5 crater radii), Addison and Brumpton (2012) noted that the Thunder Bay area would have still experienced dramatic impact-induced effects, including magnitude 10.7 earthquakes and likely tsunamis. Alternatively, it has also been suggested that some of this deformation may be related to the dominantly extensional stress regime associated with Midcontinent rifting. Local compressional (contractional) structures may form within relay zones between overlapping normal fault tips, particularly as the fault segments grow, interact, and prepare to connect. While normal fault systems are dominated by horizontal extension (pulling apart), the 3D interaction and rotation of blocks in the relay zone (or “relay ramp”) can create local stress perturbations that lead to shortening, folding, and antithetic faulting (cf. Camanni et al., 2023). Further work is required to better map the extent and character of folding and brecciation in order to suggest deformation mechanisms and causative factors. Rove shales and wackes (e.g. STOP 1-5), mapped ~2.5 km south of here by McIlwaine (1975), are not deformed. They overlie Gunflint rocks and are disconformably overlain by sandstones of the Pass Lake Formation of the Sibley Group (STOP 1-6). Figure 10. Recumbent fold in Gunflint Formation chertcarbonate rocks, STOP 1-3. Folded bedding planes are traced by dashed lines. A thin veneer of Phanerozoic(?) conglomerate (cgl) occurs on outcrop surfaces and in crevices. Two other enigmatic rocks are exposed at this location; both are conglomerates. One conglomerate occurs as thin coatings plastered on exposed outcrop surfaces and in fractures in the folded Gunflint rocks (Figures 10 and 11). It is a brown, poorly sorted, sandy, matrix-supported unit. Sibley Group (ca. 1.4 Ga) sedimentary rock clasts, ranging from sub-angular to rounded pebbles and cobbles, predominate. Most recognizable are rust-red calcareous siltstones of the Rossport Formation (with their characteristic pale reduction spots) the base of which occurs approximately 75 m stratigraphically above the Gunflint exposed here. It must also be noted that medium-grained mafic igneous clasts appear to be ca. 1.1 Ga Nipigon diabase -9- Given the presence of Sibley and Nipigon diabase �Proceedings of the 72nd ILSG Annual Meeting - Part 2 and/or enrichment (cf. Fralick and Riding, 2015). Interestingly, the exposure of stromatolitic Gunflint rocks on the west side of Highway 11-17, just opposite the Mirror Lake turnoff, only 200 m away from STOP 1-3, is notably rusty and apparently more oxidized than the vast majority of Gunflint rocks. This may represent Mesozoic paleoweathering, raising the possibility that Cretaceous deposits and paleoweathering effects may have once extended as far east as the Thunder Bay area. Any rocks that survived Pleistocene glaciation may survive in isolated patches or have been as yet unrecognized. The second conglomerate (Figures 12A and 12B) is similarly exposed as a plastered veneer draped on the exposed outcrop face. Unlike the other unit, it appears to be clast-supported and monomictic; angular, dark grey, fine-grained, shaly Gunflint fragments are cemented by calcite. This monomictic clast population suggests local derivation, perhaps a talus deposit created and cemented during the Pleistocene. Figure 11. Close-up of thin veneer of conglomerate on Gunflint substrate, showing reddish-orange Rossport Formation siltstone and Nipigon diabase fragments. clasts, the conglomerate must postdate at least Midcontinent rifting, the hitherto youngest geologic event in the local lithologic record. Although no Phanerozoic rocks have been documented in the Thunder Bay region, Cretaceous rocks have long been known to overlie the Biwabik Formation (time-correlative with the Gunflint) on the Mesabi iron range of northern Minnesota (e.g. Bergquist, 1944); “soft” iron ores there formed there during the Cretaceous. Paleomagnetic studies by Purucker (1983) in the Eldorado Beach – Nelson roads area, ~6.5 km southwest of this location, suggested that secondary enrichment of Gunflint and Mesabi iron ores took place at approximately the same time between Aptian and Cenomanian time (ca. 12594 Ma). In their study of anthraxolite in the Gunflint Formation in the Kakabeka Falls area, Hayatsu et al. Remnants of a Nipigon diabase sill form prominent, cuesta-like hills in the vicinity of this stop and around Deception and Mirror lakes (McIlwaine, 1975). Smooth, glacially polished surfaces with striae are visible at the road level in this cliffside exposure. STOP 1-4: Gunflint Formation, Blende Creek area (0369581E / 5383837N) This stop description, featuring deformed chertcarbonate units in the Gunflint Formation (Figure 13), is taken from Fralick et al. (2012): (1983) identified two very distinct macromolecular materials. These two hydrocarbon fractions were thought to represent derivation from sediments of two vastly different ages: an older one, characterized by heavier aromatic ring compounds, derived from Gunflint-aged organic remains; and another, aliphatic fraction derived from Cretaceous (or possibly Jurassic) sediments. Cretaceous microfossils were described in lateritic “buckshot” ore in the Archean Steep Rock Lake iron deposit near Atikokan (Machado, 1987) that underwent Mesozoic karstification, weathering - 10 - “Along Highway 587, rock cuts display thinly bedded, generally flat-lying sedimentary rocks of the Gunflint Formation. The outcrops we have driven past are composed of ankerite and siderite grainstones (medium-grained, sandsized iron carbonates) referred to as granular iron formation (GIF). These are common in the Thunder Bay region, dominating the near-shore of the Animikie Basin. The iron carbonate grains were produced by wave erosion of carbonate precipitates and represent storm deposits in the near-shore. The iron may have precipitated as a carbonate in this shore-proximal zone due to photosynthesizing bacteria removing CO2 from the water and thus increasing the pH and driving the carbonate phase into supersaturation. The outcrop we are looking at has these carbonate �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 12. A (left). Clast-supported, calcite- cemented conglomerate veneer over Gunflint, STOP 1-3. B (right). Close-up view of conglomerate / breccia in Figure 12A. grainstones weathering orangey-brown alternating with white chert layers. In places the chert can be seen replacing the carbonate but other layers appear to be primary chert. In the older literature an outcrop such as this would be ascribed to deeper water due to less evidence of current activity. However, because of its shore proximal location it probably formed in a Figure 13. Folded Gunflint Formation grainstones, north side of Highway 587, STOP 1-4, with locally axial-planar quartzcarbonate veins. - 11 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 quieter water location near the strand-line, i.e., a sheltered lagoonal area behind on offshore bar. These exposures are somewhat unique in that the rocks are folded; elsewhere, they are undeformed. The hinge zones, where the majority of stress is focused, are commonly fractured. These fractures may be occupied by quartzcalcite veins following the vertical axial plane. The outcrop to the west hosts numerous veins and vein breccias that strike between 40° and 45° and dip almost vertically to the southeast. These breccias contain sparry calcite, drusy quartz and also altered shale fragments, suggesting that these Rove Formation rocks likely occurred above this section during vein emplacement. A thin, northwest-dipping diabase dyke intrudes the Gunflint rocks at this location and is, in turn, cut by these veins.” Deformational features in Gunflint Formation rocks near Pass Lake have been previously ascribed to Penokean fold-and-thrust activity in the foreland (i.e. passive margin Archean basement + Gunflint Formation; Hill and Smyk, 2005). These include discrete bedding-plane faults with locally developed gouge and breccia that can be traced laterally into horizontal, hanging wall ramps with associated fault-bend folding. Previous workers had also ascribed folding to synsedimentary slumping and Keweenawan diabase sill emplacement and thought that they were attributable to local, rather than regional-scale, deformation. As introduced at STOP 1-3, there is growing support for the contention that such deformation may be related to the Sudbury impact event ca. 1850 Ma. Figure 14: Flowerpot-shaped Rove Formation concretion on wall of inactive shale quarry at STOP 1-5. a piece of organic material or other foreign object, which creates a perturbation in fluid flow with a distinct chemistry. Because the cementing agent in this case is more resistant to weathering, these concretions stand out of the soft shale and may commonly completely detach form their host rock. Groundwater and surficial water flow through the shale has led to the dissolution and subsequent precipitation of a variety of low-temperature minerals (e.g. carbonates, sulphates, hydroxides) that occur as white and yellow encrustations on the bedrock surface. One of the more unusual of these secondary minerals is yellow magnesium aluminocopiaptite ((Mg,Al) (Fe,Al)4(SO4)6(OH)2.20H2O; Resident Geologist’s Files, Thunder Bay).” STOP 1-5: “Devil’s Flower Pots” (Rove Formation concretions) 0370841E / 5382426N This stop description is taken from Fralick et al. (2012): “Just north of Highway 587, a quarry face exposure of black, fissile Rove Formation shale displays lenticular and elliptical concretions, flattened along bedding planes [Figure 14]. These structures form during diagenesis, following initial compaction and dewatering of the sediments. They represent a concentration of a cementing agent (e.g., silica, calcite) focused during the migration of fluid through the sediments. They often are nucleated around STOP 1-6: Edwards Road section (Pass Lake and Rove formations) 0371737E / 5382460N (n.b. private property; permission is required to access) This stop provides us with an excellent stratigraphic section that extends upward from the top of the Animikie Rove Formation into the Pass Lake Formation, the lowermost formation of the Sibley - 12 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 and sandstones of the Loon Lake Member, Pass Lake Formation, overlie the Rove. The conglomerate and sandstone layers are laterally discontinuous, with some conglomerates in clast-support (fluvial deposits) and some in matrix-support (sub-aerial debris-flow deposits). Successions such as this in the Sibley are typical of arid to semi-arid alluvial fans (Cheadle 1986), though this would have been a very small one. The abundant hematite probably denotes a deep water table. Clasts are locally derived from Group. The youngest detrital zircons in the Sibley Group are ca. 1.4 Ga (Rogala et al., 2007). An Rb– Sr isochron age of 1339 ± 33 Ma was determined on dolomitic mudstones from the Rossport and Kama Hill formations (Franklin 1978; Franklin et al. 1980). Recent studies of some of the concretions (quartzcarbonate + various very fine-grained impurities and inclusions) in the Pass Lake Formation, associated with late advanced diagenesis, had enough uranium to generate an age of 1483+4 Ma (W. Bleeker and H. Rochin-Banaga et al., unpublished data / personal communication, 2025; Figure 15). Together with the ca. 1500 Ma youngest detrital zircons (SHRIMP data on 3 samples; ibid), this provides a greatly improved age constraint, just marginally younger than 1500 Ma, on the deposition of the lower part of the Sibley Group. This stop description is taken from Fralick et al. (2012): “A private access road extending up the mesa provides an excellent 150 m long section exposing the disconformity between the Rove Formation and the overlying basal conglomerate and sandstones of the Pass Lake Formation [Figures 16 and 17]. The Rove shales immediately below the contact were subject to Mesoproterozoic weathering. Geochemical investigations have outlined an oxidized zone below the contact grading to a more reduced zone with abundant chlorite a few tens of centimeters lower in the section. In one area what may be a dewatering or degassing structure strongly deforms the shale. Very immature, iron oxide-rich conglomerates Figure 16. Cobble-sized clast of Gunflint Formation stromatolitic jasper/chert visible in the Loon Lake Member conglomerate exposed along the Edwards Road section, STOP 1-6. Figure 15. U-Pb concordia diagram presenting geochronological data for the Sibley Group (W. Bleeker and H. Rochin-Banaga et al., unpublished data, 2025) Figure 17. Disconformable contact (just above hammer) between weathered green Rove Formation shales and hematite-rich, basal conglomerate and sandstone of the 6-7 m thick, Loon Lake Member (Pass Lake Formation), STOP 1-6. Overlying, well-sorted, buff sandstones of the Fork Bay Member form the top of the exposure. - 13 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 the erosion of underlying units. This is sharply overlain by mature, well-sorted, medium-grained sandstones of the Fork Bay Member, Pass Lake Formation. Detrital zircon geochronology and paleocurrents (Cheadle 1986; Rogala et al. 2007) indicate that the major source of this sediment was the Trans-Hudson highlands. The travel distance accounts for its maturity compared to the locally derived underlying conglomerates. The sandstone was deposited as sheet flows into the shallow nearshore of a lacustrine system that had flooded the area (Cheadle 1986; Rogala 2003; Metsaranta 2006; Rogala et al. 2007). These sandstone layers are laterally continuous, massive to parallel-laminated, in places with trough cross-stratified or rippled tops [Figure 18]. Rare, odd features are present both in crosssectional and bedding plane views in this outcrop. These may be dewatering pipes.” exposed on this outcrop surface. These include two sets of glacial striae at 040˚ and ~060˚ and subparallel arrays of crescentic gouges and chatter marks/lunate fractures (Figure 19). En route to STOP 1-7, the highway traverses a series of baymouth bars that formed as lake levels fell from the Lake Beaver Bay stage (ca. 11 to 10.5 Ka) to the Lake Minong stage (ca. 10.5 to 8.5 Ka), connecting what had been the “island of Sibley” to the mainland near Pass Lake (Zaniewski et al., 2020; Geddes et al., 1987; see Fralick et al., 2012). This new connection formed an ideal natural trap for Palaeo-Indian hunters to use. The materials excavated at the Brohm archaeological site, on the top of the main baymouth bar, were all hunting-related projectiles and scrapers, many made onsite from chunks of jasper taconite that they carried with them from quarry sources (Zaniewski et al., 2020; MacNeish 1952). Fralick et al. (2012) noted that the matrix-supported conglomerate was probably deposited as a high-density mass-flow while the boulder-cobble, matrix-supported conglomerate probably represents a very high-viscosity mass flow as the larger clasts were suspended near the top of the flow. Upper flow regime, parallel-laminated sandstones were probably deposited by sheet-floods on an alluvial fan’s surface and are interbedded with clastsupported fluvial conglomerate. The top of the hill affords a tremendous view of Thunder Bay, Sibley Peninsula and offshore islands. A south-dipping diabase sill forms the prominent cuesta of Caribou Island. Glacial erosional features are Figure 18. Medium- to coarse-grained, well-sorted sandstone bed of the Fork Bay Member, top of hill, STOP 1-6. The majority of the bed is upper flow regime parallel laminated, with a reworked, cross-stratified top. Figure 19. Glacial erosional features exposed in the sandstone outcrop surface at the top of the hill, STOP 1-6. These include glacial striae (dashed arrows), concave up-ice crescentic gouges (CG) and concave down-ice chatter marks (CM). - 14 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 STOP 1-7: Pass Lake section (Loon Member conglomerate) 372282E / 5380560N The cliffs adjacent to the abandoned railway at Pass Lake is the type section for the Pass Lake Formation. Exposure is almost continuous for 3.2 km along the tracks and provides a ~50 m-thick stratigraphic section. Rove Formation shales, exposed at the northwestern end of the cliff exposure, disconformably underlie the Pass Lake Formation but are not exposed here. This cliff face, a popular destination for local rock climbers, exposes the basal Loon Member conglomerate and overlying, buff sandstones of the Fork Bay Member (Pass Lake Formation; Figure 20). A description was provided by Fralick et al. (2012): “The basal conglomerate thins and thickens laterally, pinching down to pebbly sandstone in places. Clasts are generally surrounded and dominated by local Gunflint Formation lithologies. The matrix is poorly sorted. The conglomerates are overlain by a thinningupward sequence of sandstone beds capped by siltstones on the top of the cliff. Individual beds are reasonably laterally continuous though sometimes lens out. They are dominated by upper flow regime parallel lamination with occasional ripples and small-scale dunes on their tops. Figure 20. Pass Lake section exposure of Loon Lake Member conglomerate overlain by Fork Bay Member sandstone at STOP 1-7. STOP 1-8: Neoarchean Pyroclastic and Clastic Sedimentary Rocks 360568E / 5379943 Both alluvial fan-braided fluvial and shallow lacustrine (Cheadle, 1986; Franklin et al., 1980, respectively) depositional environments have been proposed. The bedding organization of the conglomerates exposed here is somewhat different than those observed earlier. This opens the possibility that the conglomerates at this location were reworked by wave activity during initial lacustrine flooding. This 100 m-long rock cut on the northwest side of Highway 11-17 was exposed by highway construction ca. 2012. It features a remarkable exposure of Neoarchean pyroclastic and clastic sedimentary rocks of the Shebandowan greenstone belt that strike ~140˚ and dip steeply northeast (Figure 21). These supracrustal rocks are intruded by granitoid rocks of the McKenzie granite and may represent a large pendant within the intrusion. The exposure was the subject of an undergraduate thesis by Bjorkman (2014), from which most of the descriptions will be gleaned. The sandstone beds again represent sheetfloods, forming sand-flats in the shallow lake. The thinning- and fining-upward sequence of sandstone beds is a classic example of a transgressive succession showing decreased sand supply through time as the shoreline moves further away from the area.” Bjorkman (2014) identified 13 lithofacies/lithologic units in this complex section: Overlying red-orange Rossport Formation siltstones begin to outcrop approximately 1.2 km east of STOP 1-7 (see Fralick et al., 2012 for stop descriptions). This exposure exemplifies the close connection between Neoarchean pyroclastic activity and sedimentation (Figure 22). Bjorkman (2014) suggested that these rocks were deposited in a vent-proximal environment, a contention supported by the presence of graded ash beds, high-velocity base surge deposits and impact structures from pyroclastic bombs (Figure 23). - 15 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Lithofacies / Interpretation 1 Lahar – debris flow 2 Ash fall 3 Fluvial reworking and base surge deposits 4 Ash fall 5 Lag deposit 6 Slump 7 Lahar 8 Lahar / channelized debris flow 9 Ash tuff 10 Hornblendite 11 Hornblendite 12 Hornblendite 13 Syenite Description Unsorted, clast-supported, conglomerate; clasts are pebble-sized to small boulder-sized within a medium-grained, sand-sized matrix Fine-grained to medium-grained, sandy, continuous beds; parallel laminated with no crossbedding, with an average thickness of 1 cm or less Cross-bedded and graded, medium-grained sandstone beds, which occur in alternating sequences; this unit has a sharp basal contact with the lower Lithofacies 2 and a poorly defined contact with upper units. The transitions from the graded beds to the cross-stratified beds are distinct. Parallel-laminated, continuous layers of medium-grained, graded beds, more rarely observed to be cross-bedded at very low angles. Clast-supported conglomerate in which clasts are very uniform and commonly cobble-sized. The clasts are flattened and oval-ellipsoidal, with rounded edges. The long axes of the clasts occasionally have tail-like tips. Disturbed beds of material very similar to that found within Lithofacies 4. The parallel-laminated strata are disrupted by failure of the slope and are truncated by an angular disconformity of the overlying unit. There are rubble blocks adjacent to the truncated strata. These blocks of failed beds lie along the base of this facies, with no evidence of sorting after the failure. There is no grading in the matrix, which is massive, medium-grained sandstone. Repetitive sequences of normally graded, medium-grained sandstone beds, gravelly matrix supported beds, and non-graded massive beds composed of medium-grained sand. Discontinuous, lens-shaped beds are very common. The normal graded beds are composed of coarse-grained sandstone, which grades into fine-grained tops of beds. These often have eroded, scoured tops, with very distinctly defined bases. Cross-bedding is common. Massive graded conglomerate with angular to very rounded and moderately flattened clasts. The clasts appear monomictic and range in size between 5-15 cm, the majority being 12 cm by 7 cm. The clasts make up 70% of the total composition, while the matrix is mostly a uniform mediumgrained sandy composition, with 10% coarser sand-sized fragments. The unit is on average 3-5 m wide. Fine-grained, sand-sized matrix with medium-grained and subhedral porphyritic feldspar crystals. The weathering surface is very irregular as the feldspars stand-out from the matrix. The unit occurs sporadically, locally intruded by dark green material. The average thickness varies between 50 cm to 100 cm. There is no grading throughout this unit, and the unit conforms to the same stratigraphy as the surrounding units, which is most often Lithofacies Association 1. Medium-grained dyke which crosscuts stratigraphy. The largest of the intrusive dikes, it can be traced through the entire outcrop. It is distinguished by the very irregular shape of its contacts with the host rock. The matrix consists of green equigranular, subhedral crystals in the middle of the intrusion and lighter altered plagioclase crystals along finer-grained contacts. The body intrudes (brecciates) itself where the dike dilates. Other smaller dikes crosscut this one. Cobbleto boulder-sized xenoliths were noted. Medium-grained, green-grey mafic dyke, 5-7 cm wide, with equal amounts of mafic and felsic minerals. The dike cuts through the green intrusive veinlets. A set of dark green-grey dykes, up to 0.5 m in width, striking approximately the same direction as Lithofacies 10; may be sill-like intrusions, wispy and infiltrating intrusions which engulf clastic material. This unit commonly contains wall rock xenoliths, which are very sharp and angular. Medium- to coarse-grained, subvertical and east-southeast-striking dykes. The dykes are the youngest rock type in the outcrop and are noted regionally. They are composed of red feldspar, amphibole, biotite, and quartz. The red feldspar gives the rock a brick-red colour. A combination of subaerial and shallow subaqueous conditions likely existed at the time of deposition, with fluvial reworking and deposition occurring during periods of volcanic dormancy. Phreatomagmatic processes, similar to those that produce maar craters, likely predominated. The calc-alkalic geochemistry (Figure 24), pyroclastic volcanism and subaerial/shallow water to fluvial clastic sedimentary rocks suggest that these rocks are part of the younger Shebandowan assemblage - 16 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 21. Map of the main outcrop, STOP 1-8 (Bjorkman, 2014). Lithofacies Association 1 through 9 are (resedimented) pyroclastic and clastic sedimentary units; lithofacies association 10 through 14 are crosscutting dykes. of the Wawa subprovince. Shebandowan rocks (ca. 2690-2680 Ma), unconformably overlying the older (ca. 2720 Ma) Greenwater assemblage rocks, were deposited in fault-bounded, pull-apart basins during regional transpressive (D2) deformation. North and south of the main, supracrustal-dominated outcrop, pink granitoid rocks associated with the McKenzie granite occur (Figure 25). The McKenzie granite is approximately 22 km long (east-west) by 3.2 km wide (north-south) and has been divided into two segments that are separated by a fault (Scott, 1990). Based on the mapping of Scott (1990), and the interpretation of aeromagnetic data, Metsaranta (2015) suggested that the McKenzie granite comprises multiple distinct intrusive bodies, and referred to the western segment as the Mount Baldy intrusion. Figure 22. Resedimented pyroclastic material as conglomeratic beds and lenses, STOP 1-8. - 17 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 24: AFM plot of samples collected and analyzed by Bjorkman (2014), showing the calc-alkaline nature of the resedimented pyroclastic rocks at STOP 1-8. Figure 23: Large pyroclasts, commonly with attendant bomb sags, STOP 1-8. The Neoarchean, S-type McKenzie granite (Hughes, 2016) is primarily a peraluminous quartz monzonite, with mineral assemblages characterized by microcline-plagioclase-quartzmuscovite-biotite with minor amounts of inequigranular hornblende, chlorite, titanite and rarely calcite. The McKenzie granite exhibits a peraluminous geochemistry, with SiO2 contents ranging from 63.8 to 68.2 weight % along with enrichment in light rare earth elements and fractionated heavy rare earth elements, decreasing trends of major oxides, transition metals and high field strength elements. Scattering of the large ion lithophile elements on discrimination diagrams is likely due to remobilization during chlorite, sericite and carbonate alteration (Hughes et al., 2017). It is proposed to have formed in a similar way to the model proposed for the later stages of the Figure 25. Photo illustrating cross-cutting relationships at STOP 1-8. The granitoid dyke in the bottom half of the photo that cross-cuts all lithologies, including a hornblendite dyke (top center), is associated with the nearby McKenzie granite. genesis of the nearby Dog Lake Granite Chain, which involved partial melting of a mantle wedge beneath the Wawa-Abitibi island arc. The proposed late-stage emplacement model is consistent with recent U-Pb geochronology (Puumala et al., 2015) that indicated that the McKenzie granite was emplaced at 2672.6 ± 1.5 Ma (zircon, U/Pb thermal ionization mass spectrometry). These S-type melts, formed from the partial melting of metasedimentary rocks, may have interacted with I-type melts, allowing for the variations in geochemical and petrological data that are observed in the McKenzie granite, such as the presence of hornblende, that are not common for standard S-type granites. - 18 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 STOP 1-9: Gunflint / Archean Unconformity, Crystal Beach 358661E / 5378895N This road cut on the northwest side of Highway 1117 near Crystal Beach provides another outstanding exposure of the contact between Archean basement and unconformably overlying Paleoproterozoic Gunflint Formation, similar to that exposed at STOP 1-1. However, there are a number of unique features here that warrant description and examination. The basement at this location is the Neoarchean McKenzie granite (2672 Ma) which has been conspicuously altered 1 to 3 m below the unconformity. The original pink granite has been altered to dark green chlorite (+ clays?) up to 2 m; alteration intensity increases upward towards the unconformity. Unaltered pink, K-spar-phyric granite gives way to altered versions in which the matrix is incipiently to completely chloritized, leaving relict, unaltered K-spar phenocrysts. The phenocrysts have also been replaced (saussurite + clays + chlorite) in the most intensely altered granite, leaving only relict quartz (Figure 26). The correlation between alteration intensity and proximity to the unconformity suggests that the altered rocks may represent a regolith/saprolite. Such alteration is often interpreted as a combination of ancient subaerial weathering (true paleosols) and later fluid migration from the overlying iron formation. Geochemical studies by Yip (2016) and Fralick (personal communication, 2024) at this location suggest that iron-rich Gunflint fluids replaced and masked the geochemical signature of the original paleosol. Similar alteration characteristics were described by Kronberg and Fralick (1992), who noted that alteration of ferromagnesian minerals in felsic Archean rocks Figure 26. Selected hand samples of McKenzie granite from STOP 1-9, showing progressive alteration (chloritization) from unaltered (left) through incipient and pervasive matrix replacement (second and third from left, respectively) to complete replacement of matrix and K-spar phenocrysts (far right). southwest of Thunder Bay was apparently due to diffusion of iron-rich, Gunflint-derived fluids across the Proterozoic -Archean unconformity, consistent with slow mineral-fluid exchanges under diagenetic or low-grade metamorphic conditions. Chemical changes in mafic minerals include additions of iron, manganese, and water and losses of silica, calcium, and magnesium. They concluded that these chemical changes occurred as Gunflint fluids diffused into underlying rock over a time frame of 105-107 years. Spalling of overlying Gunflint rocks has exposed a section of smooth, bare basement paleosurface (Figure 27). The contention of Pre-Gunflint weathering is supported by the occurrence of boulder-sized, spheroidally weathered, altered granitic corestones on the paleosurface, where they are enveloped by Kakabeka Member (basal) conglomerate and saprolite/ regolith, and are draped by Gunflint grainstones (Figure 28). Kakabeka conglomerate infills depressions in the paleosurface and fractures that extend down into weathered basement. The conglomerate here consists largely of resistate quartz pebbles in a chloritic, Figure 27: Smooth, curved, bare Archean basement paleosurface (accentuated in half-shadow above yellow field notebook), exposed below overlying, draped Gunflint grainstones, STOP 1-9. - 19 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 saprolitic/regolith matrix. Although this is perhaps the first documented example of corestones in the Gunflint or Biwabik formations, Paleoproterozoic (ca. 1.85 Ga) weathering-produced corestones in the Flin FlonCreighton area of Manitoba and Saskatchewan were documented by Sindol et al. (2020). Many of the joint surfaces and fractures in this exposure are covered and infilled by vein minerals, mainly quartz/amethyst, barite, fluorite, calcite with rare base metal sulphides (pyrite, chalcopyrite, galena, acanthite). These veins constitute the 7Z amethyst occurrence (Figure 29), first explored ca. 1890 (Ontario Mineral Inventory, https://www.geologyontario.mines. gov.on.ca/mineral-inventory/MDI52A10SW00007). The following description of the occurrence is excerpted from Puumala et al. (2015). Figure 29. Amethyst-bearing vein hosted in the Gunflint Formation at the 7Z occurrence. unconformity and are hosted by both Gunflint and granitic rocks. Gunflint rocks are strongly silicified adjacent to the veins. The exposed width of the vein system is approximately 10 m. The 7Z amethyst occurrence is hosted in a vein system and/or breccia zone that strikes 050º and is located approximately at the unconformity between sedimentary rocks of the Paleoproterozoic Gunflint Formation and Neoarchean intrusive rocks of the McKenzie granite stock. The amethyst-bearing vein system has been exposed in a series of 3 historic trenches over a strike length of 180 m. The majority of the amethyst-bearing veins strike 050º (i.e., parallel to the breccia zone) with near-vertical dips. The vein widths are variable, ranging from centimetre- to metrescale. In the Gunflint Formation rocks, a nearhorizontal set of narrow veins also occurs along bedding plane fractures. A third set of narrow, approximately north-striking veins, was also observed immediately to the south of the main breccia zone in road cuts along the north side of Highway 11-17. The portion of the vein system exposed in the southwestern and central trenches is hosted by rocks of the Gunflint Formation, while the veins exposed in the northeastern trench occur at the Figure 28. Spheroidally weathered, chloritized Neoarchean granitic corestone boulders resting on the paleosurface at the Paleoproterozoic-Archean unconformity, STOP 1-9. The corestones are enveloped by saprolitic sediments and conglomerate/regolith, and overlain by draping Gunflint grainstones. The amethystine quartz in this vein system shows a wide variation in colour, ranging from light pink (i.e., rose quartz) through to deep purple. Colourless to white quartz and smoky quartz are also abundant. Veins hosted by granite tend to contain lighter coloured amethyst, while deep purple amethyst and smoky quartz are most likely to be found in the southwestern trench, which is hosted by Gunflint Formation rocks. Most amethyst crystal points are on the order of 1 cm wide. However, much larger crystals were observed in some vugs. Crystals hosted in the Gunflint Formation rocks commonly have a surface coating of hematite. Although recent sampling has reported no significant silver values, a local newspaper reported in 1890 that 7Z was “a veritable mountain of amethyst with rich surface signs of silver” (ibid). This vein system is an - 20 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 example of a broad group of silver-bearing, carbonatequartz veins that typically occur in Animikie Group sedimentary rocks, often in close association with the Archean-Proterozoic unconformity and Midcontinent Rift-related diabase sills (Oja, 1967; Franklin et al., 1986; Kissin, 1992). They likely formed from metamorphically generated fluid from in the Midcontinent Rift and expelled along rift-bounding faults (Smyk and Frankin, 2007). largely based on a former outcrop exposure that was removed during highway reconstruction in 2011. “This is the only outcrop showing a complete ~ 3 m cross-section of the ejecta-bearing debrisite layer extending from Gunflint chert-carbonate up into the basal Rove Formation, which is overlain STOP 1-10: Terry Fox National Historic Monument 339836E / 5372406N This stop includes opportunities to view outcrop exposures near the Terry Fox National Historic Monument and lookout that commemorates Terry Fox’s 143-day, 5373-km Marathon of Hope run to raise money for cancer research in 1980, which continues to inspire global fundraising efforts. A number of rock types and features are exposed in the road cuts that flank the highway and access road near the monument (Figure 30). A prominent, columnarjointed Nipigon diabase sill (Terry Fox sill; Magnus, 2012; Magnus and Kissin, 2010) intrudes and caps these Rove and Gunflint formation sedimentary rocks. As a result, this site displays a complete stratigraphic section from the Gunflint Formation, through the Sudbury Impact Layer (SIL) and up into the overlying Rove Formation. Disconformities appear at both the base and top of the SIL (Addison and Brumpton, 2012). Figure 31. Rocks of the Sudbury Impact Layer (grey) and Rove formation (black) are visible in this photo from STOP 1-10. Geologist’s hand is located at the top of the Sudbury Impact Layer. The description of the SIL (Figures 31 and 32) at this location by Addison and Brumpton (2012) was Figure 30. This quarried rock face adjacent to the Terry Fox Lookout road displays a cross-section that includes (bottom left to top right) the Gunflint Formation, Sudbury Impact Layer (SIL), Rove Formation and Nipigon diabase. A Midcontinent Rift-related normal fault exhibiting approximately 4 to 5 metres of vertical displacement is visible near the left margin of the quarry face and is highlighted with a dashed line. Figure 32. The weathered outcrop (now gone) at STOP 1-10 in 2010 (Addison and Brumpton, 2012). Carbonatereplaced devitrified vesicular impact glass shapes and tektites were then visible on the weathered surface. The Ocean Transgression Sequence is composed of ankerite grainstones identical to those of the Gunflint and probably represents a limited transgression millions of years prior to the deposition of the Rove Formation (P. Fralick, personal communication, 2026). - 21 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 in turn by a diabase sill. An iron-rich alteration profile, heavily replaced by secondary pyrite, lies ~ 1 m below the base of the debrisite and a few metres northeast of the main outcrop. weave through this spherule-rich material but on a much finer scale than at Hillcrest Park. Red-brown agate 3-8 cm thick lies on top of the spherule-rich layer. Laterally discontinuous vertical digitate projections extend down from the top and project up from the base of this agate layer. They are similar in shape and size to the agate stalactites in vugs at Hillcrest Park, except that in this case the spaces between the projections were subsequently infilled by more agate. The red-brown colour is similar to that of the iron-rich alteration profile overlying it but it is a less saturated hue. The basal SIL is a recessively weathering, locally sheared, clastic layer about 0.5 m thick containing crushed spherule clusters, some of which are aligned subvertically instead of in the usual subhorizontal position. Several sets of subhorizontal slickensides, whose striae are aligned at a 140º azimuth, are found at various levels within this layer. Postdepositional anastomosing chert has replaced much of this basal sheared layer, obliterating considerable structural detail. Non-ejecta features include centimetre to millimetre-sized angular chert clasts and angular, subrounded to round Gunflint Formation iron carbonate clasts plus two rounded crystalline rocks with prominent alteration rinds. The presence of clasts with weathering rinds reinforces the idea that Gunflint clasts lacking such rinds were freshly fractured by impactgenerated earthquakes before being incorporated into the debrisite. An iron-rich alteration profile on top of the spherule-rich layer, consisting of hematite has been largely replaced by secondary pyrite. Prominent deformed spherule clusters are locally present. The total thickness of all these ejectabearing layers is 3 m. The top of this iron-rich layer marks a return to carbonate deposition. The basal 10-15 cm of this 80-100 cm thick carbonate zone is unstratified and shows dark, angular, commonly rectangular, millimetre-centimetre-sized rip-up mudstone clasts and probable Gunflint Formations clasts. This is followed by millimetre- to centimetre-scale layered carbonate strata topped by a zone with a few poorly defined, laterally discontinuous beds containing centimetre-scale, angular carbonate clasts. The main body of the 2.2 m thick debrisite lies in sharp contact over the basal sheared clastic unit. It is so heavily replaced by recrystallized dolomite that any possible ejecta features are only seen as vaguely outlined shapes on weathered surfaces or in thin section. Almost all detail, including any vesicles in possible DVIG- [devitrified vesicular impact glass] shaped clasts, has been destroyed. Tektites and microtektites may be present, based upon shape and rare faint devitrification textures. A single, polycrystalline, rounded quartz grain shows faint planar features. Both angular and rounded millimetre-scale chert clasts are also present, but not common. A 5-20 cm thick undulating, dark brown, recessively weathering, spherule-cluster-rich layer appears as a groove across the cliff face at the top of the dolomite-replaced debrisite. This mass of spherule clusters is much more concentrated than seen at any other location or than is suggested by faint shapes in the main dolomite-replaced layer immediately beneath it. These concentrated clusters seem to be the residuum of a thicker layer. Plentiful, thin anastomosing post-depositional chert strands The carbonate then makes an abrupt transition to 10-15 cm of gray siltstone and is overtopped by 10-15 cm of black, rusty weathering shale characteristic of the Rove Formation. The black shale is interrupted by 5 cm of chert before returning to 0.9-1.2 m of black, rusty weathering shale which is overlain in turn by a diabase sill more than 8 m thick. The shale is less friable than typical lower Rove shale, probably the result of low-grade metamorphism induced by the overlying sill.” A 050˚-060˚-striking normal fault, perhaps related to Midcontinent Rift-related extension, has displaced Animikie rocks and diabase 4 to 5 m. Koroscil (2013) identified thrust faults, mainly expressed as small discrete bedding plane faults with few kinematic indicators or piercing points to quantify the displacement. Thrust faults within the SIL were - 22 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 identified by slickenlines or slickenfibres on fault plane surfaces. The faults can be traced along strike until they are either covered by overburden or cut by a prominent normal fault which displaces all units in the hanging wall down to the south several metres (ibid). Reid-Sharp (2016) described faults, related damage zones and calcite vein breccias along the highway ~2 km northeast of STOP 1-10. Normal faults that transect Gunflint Formation + Archean basement rocks, strike east-northeast and dip to the southeast, were also ascribed to extension during Midcontinent rifting. The past-producing Thunder Bay Silver Mine is situated between the highway and the Terry Fox access road. Discovered in 1866 by P. McKellar, it was mined underground until 1874 via four shallow (8 to 21 m deep) shafts (Ontario Mineral Inventory, https://www. geologyontario.mines.gov.on.ca/mineral-inventory/ MDI52A06NE00005). Mineralization occurs in calcite-quartz veins that are hosted in chert-carbonates (Gunflint Formation) and shales (Rove Formation). The host rocks strike 034/22 southeast in the vicinity of the vein but subhorizontally 30.5 m to the northwest beneath a diabase sill 12.2 m thick. A 3 m wide composite vein or stockwork system consisting of 2.5 cm wide quartz-carbonate veinlets lies within and parallel to a fault that also strikes 034/65 northwest. Ore was mined locally over the total length of 182.9 m. Native silver and acanthite occurred in pockets 7.6 - 45.7 cm thick by 1.8 -12.2 m in length, the silver being in leaves and grains irregularly distributed in a gangue of quartz, with some calcite, galena, sphalerite, and pyrite. A second vein of calcite occurs in a parallel fault 6.1 m southeast of the composite vein (ibid; Sergiades, 1968). When first opened, two orebodies were found, one next to the north or hanging-wall and one in the middle (Tanton, 1931). The ore was brought to a stamp mill at the mouth of the Current River, 4 km south of the mine (Figure 33). Production totaled an estimated $20 000 (Bowen, 1911), or approximately 15 000 ounces of silver. Figure 33. Stamp mill of the Thunder Bay Silver Mine at the mouth of the Current River, ca. 1880. Shegelski (1982; Figure 34) and later described in the context of impact-related brecciation by Addison et al. (2010) and Addison and Brumpton (2012, Figure 35): “A bedrock exposure, about 5 m by 15 m, in a private yard in Thunder Bay contains a spectacular debrisite exposure composed mainly of Gunflint chert-carbonate breccia and ejecta, primarily DVIG [devitrified vesicular impact glass], which is surrounded and partially replaced by blocky calcite cement. The debrisite remnant preserved here is 0-0.5 m thick and unconformably overlies stromatolites and chloritic grainstone of the uppermost Gunflint Formation. An iron-rich alteration zone exists approximately 30 cm below the erosive contact between the debrisite and the Gunflint bedrock. DVIG clasts are up to 2 cm across. Vesicles range from round to ovoid to nearly flat. Angular quartz and feldspar grains, chert shards, and chloritic granules are also present. Quartz grains with PDFs have not been found here.” The SIL is also exposed nearby at Hillcrest Park and along Banning Street. STOP 1-11: Sudbury Impact Layer, Markland and Hill Streets 334163E / 5366301N (n.b. Private Property, ask for permission to access. Be very careful not to step on any plants. No hammers are allowed.) Another spectacular debrisite breccia of the Sudbury Impact Layer is exposed at the corner of Markland and Hill streets. This outcrop was mapped in detail by - 23 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 34. Detailed map of the debrisite breccia outcrop at STOP 1-11 by Shegelski (1982) Figure 35. (from Addison and Brumpton, 2012) A – Gunflint Formation stromatolites exposed on a glacially truncated surface, STOP 1-11. While it is not recognizable in the photo, debrisite lies over stromatolites at upper right of the photo. B – Angular to slightly subangular clast-supported Gunflint Formation breccia with a finer DVIG-rich and calcite-rich matrix, all of which lies directly on Gunflint stromatolites, STOP 1-11. The angular clasts suggest a short travel distance from their point of origin. C – DVIG clasts within a recrystallized calcite matrix, STOP 1-11. The silicate devitrification product supports growth of a black lichen, whereas calcite prevents lichen growth. The vesicles are calcite infilled. D – Orange, weathered accretionary lapilli in a recrystallized carbonate matrix, Hillcrest Park. - 24 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Field Trip Stop Descriptions - Day Two Day Two comprises stops to a variety of locations south and west of Thunder Bay (Figure 36). This area is underlain by a variety of rocks that record almost three billion years of local geologic history, spanning from the Neoarchean (ca. 2.7 Ga) to the Paleoproterozoic (ca. 1.8 Ga) and Mesoproterozoic (ca. 1.4 and 1.1 Ga). Unconsolidated glacial and post-glacial deposits and features attest to a long-lived, Pleistocene glaciation record. All GPS coordinates are NAD83, UTM Zone 16. Figure 36. Generalized geology of the Thunder Bay area, showing Day Two field trip stop locations. Geology from Map M2232 (Carter et al., 1973). STOP 2-1: Mount McKay Lookout (Anemki Wajiw) 0331126E / 5357384N (n.b. admission via a gate operated by Fort William First Nation) Our first stop provides not only a panoramic view of Thunder Bay and surrounding area, but also stacked Logan sills which have produced the iconic mesa topography of Mount McKay and other similar mesas to the south and west in the Animikie-underlain Logan basin, collectively known as the Nor’westers. This location had previously been described by Cundari et al. (2012). Mount McKay is also known as Anemki Wajiw (“Thunder Mountain”) in Ojibwe. The summit, at 482 m ASL, is approximately 300 m higher than Lake Superior. The stop is centered on the lookout area (Figure 37), which represents the top of the lower sill at approximately 337 m ASL. The upper, ~60 m thick, columnar-jointed sill and adjacent, hornfelsed Figure 37. View of the top of Mount McKay, capped by the ~60 m-thick, upper Logan diabase sill. The Lookout level is underlain by the top of the lower sill. - 25 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Rove Formation wacke can be accessed by way of a hiking trail which leads to the summit. Although stacked sills have been encountered in drilling, few examples exist in surface exposures. As many at 14 sills were reported, for example, in a 705 m-deep drill hole in central Pardee Township by Dumont Nickel Inc. (Assessment Files, Thunder Bay South Resident Geologist’s District, Thunder Bay). al., 2007). Resampling of Zr-enriched, pegmatoidal, upper portion of the Logan Sill capping Mount McKay and re-analysis of baddeleyite and magmatic zircon yielded an age of 1106.3 + 2.0 Ma (Bleeker et al., 2020). This, and similar ages elsewhere, led Bleeker et al. (2020) to favour a relatively sharp onset of high-volume mafic-ultramafic magmatism in the Midcontinent Rift at ca. 1110 to 1106 Ma. The rugged topography (Figure 38) has produced extensive colluvial deposits and talus slopes. Unconsolidated, sandy lacustrine and fluviolacustrine deposits occur below the bedrock- and colluvium-predominated slopes. Abandoned shoreline escarpments and beach bars, visible between the lookout and Lake Superior, reflect higher post-glacial lake levels (Burwasser, 1977). Feldspar-phyric patches, common near upper chilled sill contacts, are present in an exposure of the upper, chilled contact of the lower sill along a path to the west of the clearing (Figure 39). A tentative age of 1114.7 ± 1.1 Ma was determined from a Logan sill on Mount McKay, using a limited selection of very small baddeleyite grains (Heaman et Figure 39. Polygonal jointing in upper chilled surface of lower diabase sill, STOP 2-1. Figure 38. Shaded relief LiDAR image of area south of Thunder Bay, showing topographic relief (i.e. gently southdipping mesas/cuestas) resulting from erosion-resistant mafic sills and, to a lesser extent, siliceous wackes in the Rove Formation (data from https://www.arcgis.com/apps/ mapviewer/index.html?url=https://ws.geoservices.lrc.gov. on.ca/arcgis5/rest/services/Elevation/FRI_DTM_SPL/ ImageServer). STOPS 2-1 and 2-2 are also shown. Logan sills generally consist of fine- to coarsegrained, ophitic to intergranular, quartz tholeiitic diabase/gabbro (Smith and Sutcliffe, 1987; Geul, 1970, 1973). Coarse-grained, intergranular gabbro, locally rich in granophyric mesostasis, is common in the interior of the thicker sills. Geochemical data from sampling of the upper and lower sills by Hart and Magyarosi (2004) are provided in Figure 40. These sills represent the northernmost known extent of Logan diabase sills near Thunder Bay. Nipigon diabase sills occur within the city and extend northward to the Nipigon Embayment. - 26 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 40. Primitive mantle-normalized trace element plots for upper and lower sills at Mount McKay with Nipigon sill sample for comparison. Data from Hart and Magyarosi (2004) and Hollings et al. (2011). Normalizing values from Sun and McDonough (1989). Nipigon sills are characterized by generally lower incompatible trace element abundances, lower TiO2 content, and a distinct negative Nb–Ta anomaly. They typically have lower Gd/Ybcn ratios compared to Logan sills. Logan Sills are characterized by higher TiO2 and higher Gd/Ybcn ratios, indicating a greater degree of heavy rare earth element fractionation (cf. Hollings et al., 2010). Riverdale sills (STOP 2-2) are geochemically distinguishable from both Nipigon and Logan diabase (Figure 41). STOP 2-2: Riverdale Quarry 322418E / 5355233N (n.b. Private property; permission is required to access. Caution advised on site due to slip and fall risks associated with steep slopes and vertical rock faces) This former shale quarry exposes a ~20 m-thick section of the lower Rove Formation, overlain by a ~12 m-thick Riverdale, columnar-jointed, gabbronorite sill related to Midcontinent Rift magmatism (Figure 41). This location was previously described by Cundari et al. (2012): “Sampling by Smyk and Hollings (2007) identified this as a Riverdale gabbronorite Figure 41. Discrimination diagrams for mafic and ultramafic intrusions near Thunder Bay (from Cundari et al. 2012). Data are from Hollings et al. (2007a) and Puchalski (2010). Normalizing values from Sun and McDonough (1989). - 27 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 lie within the major element abundances; olivine gabbros are lower in SiO2 and elevated in MgO, Cr, Co, and Ni compared to the gabbronorite samples. The sill does not display any evidence for Figure 42. Riverdale gabbronorite sill capping section of Rove Formation clastic sedimentary rocks, Riverdale Quarry. (Photo taken in 2008. Arrow points to geologist for scale.) sill in Rove Formation shale, wacke and minor tuffaceous units. Subsequent detailed petrographic and geochemical analyses were carried out by Puchalski (2010). Samples were taken through stratigraphy at the quarry to investigate composition and contamination, as well as to test whether the sill had undergone differentiation. The following section provides a concise summary of those findings. differentiation as shown by the erratic trends of MgO, SiO2, TiO2, Cr and Ni through stratigraphy. An olivine gabbro in the center of the sill displays elevated MgO, Cr, and Ni values as well as a lower abundance of silica when compared to the surrounding samples. This is likely the result of a slightly more primitive magma intruding the center of the sill. The lack of chilled margins between the olivine gabbro and the gabbronorite suggest that the sill had not fully crystallized when the second pulse intruded. A sample of a 60 cm wide north-trending diabase dyke which intrudes the sill near the western end of the quarry is geochemically comparable to the surrounding Logan sills. Contamination by the Rove shale is evident in samples taken from close to the contact (<1 m above the contact). These samples display higher SiO2 values as well as lower Nb/Nb* and Gd/Ybn values than the rest of the unit. As the Rove shale displays significantly lower Nb/Nb* and Gd/Ybn values than that of the surrounding gabbronorite. The Rove shale is the likely source of this contamination signature. Two different pulses of magma are recognized within the Riverdale sill, based on contamination signatures denoted by negative niobium anomalies. The less-contaminated samples are typically found towards the core of the intrusion with rocks above and below displaying a greater degree of contamination. Samples taken within 60 cm of a shale xenolith do not display a distinct negative niobium anomaly. This shows that the source of contamination responsible for the negative niobium anomaly is not the Rove shale but is likely a crustal component from depth. εNd (T=1100 Ma) values of -1.6 to -1.9 for the Riverdale Sill are consistent with this model (Smyk and Hollings, 2009). The mafic intrusive rocks within the quarry are dominantly classified as gabbronorites with olivine gabbro present towards the center of the sill. The gabbronorites are generally fine-grained with plagioclase occurring as subhedral laths. Orthopyroxene is present in greater abundance than clinopyroxene, occurring as anhedral to subhedral crystals. Varying degrees of alteration are manifested as sericitization of plagioclase and chloritization of pyroxene. The olivine gabbro is texturally similar to the gabbronorite, albeit with a higher modal percentage of fine-grained, anhedral to euhedral olivine. In most samples, olivine is replaced by serpentine, producing secondary quartz and calcite, as well as minor magnetite. Alteration is significantly greater in the narrow, chilled margin at the contact. Pyrite occurs throughout the unit; minor chalcopyrite has also been noted. Sampling for whole rock major and trace element geochemistry was undertaken by Puchalski (2010) throughout the 10 m exposure at 1-m intervals. Olivine gabbro samples display broadly similar trace element characteristics to those of the gabbronorite samples. Differences Although the Riverdale sill is located near Logan sills, it remains petrographically and geochemically distinct from them [Figure 42]. Geochemical discrimination based on La/Smn (LREE) vs. Gd/Ybn (HREE) shows characteristics - 28 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 similar to those for the ultramafic units of the Nipigon Embayment (e.g., Disraeli, Kitto, Hele and Seagull), closely resembling the mafic to ultramafic Jackfish sill. The Jackfish sill is finergrained and displays a higher modal abundance of olivine than the Nipigon sills surrounding it (Hollings et al., 2007a). This suggests that the Riverdale sill may be genetically related to the ultramafic and mafic to ultramafic units of the Nipigon Embayment. This is consistent with the reversed polarity of the Riverdale sill (Hollings et al., 2010).” A number of features are visible at or near the exposed upper and lower sill contacts (Figure 43). Calcite-filled vesicles define a crudely developed Figure 43. Lower gabbronorite sill contact. (A) Delamination of Rove shales by injection of gabbronorite sill magma; (B) Chilled margin of gabbronorite sill against hornfelsed Rove shale. layer/joint filling(?) in medium-grained gabbronorite, ~1 m above the lower sill contact. Stoping and delamination of Rove shales is also evident here. Thin, parallel chilled margins, perhaps representing multiple influxes of magma, occur above the lower sill contact. A narrow (75 cm) diabase dyke with Logan sill-like geochemistry intrudes the Riverdale gabbronorite sill near the western end of the quarry exposure (Figure 44). Glacial striae are visible on exposed outcrop surfaces at 060˚ and 075˚. STOP 2-3: Sudbury Impact Layer, Highway 588 0307539E / 5357977N Figure 44. Narrow diabase dyke with Logan sill-like geochemistry intruding Riverdale gabbronorite sill, Riverdale Quarry. Scale card straddles the eastern dyke contact. This stop, while having lost much of the best exposure of the Sudbury Impact Layer (SIL) due to ongoing highway construction, still provides an opportunity to view some of the features associated with the SIL in the affected ankeritic, Gunflint Formation chertcarbonate rocks. The SIL was also intersected a few metres below surface in a shallow drill hole, collared in Rove Formation shales in an abandoned quarry approximately 300 m south-southwest of STOP 2-3. This location was previously described by Addison and Brumpton (2012): - 29 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 “When first observed in 2000, the Hwy 588 outcrop was a bedrock exposure in the ditch on the northwest side of the highway, 2.4 km southwest of the hamlet of Stanley. It was a glacially polished and striated surface showing erosively truncated stromatolites up to 0.5 m diameter, some of which were surrounded by accretionary lapilli 3-25 mm in diameter [Figure 45]. Ankeritic grainstone and chloritic grainstone surrounded other stromatolites. This exposure was subsequently blasted to deepen the ditch and the blasted rock now lines the ditch slopes, giving a highly fragmented cross-section and plan view of the exposure. Since then, we have exposed bedrock in the ditch about 50 m southwest of the first exposure. It shows a glacially striated surface of exposed stromatolites and shattered, but insitu black chert with an ankeritic grainstone filling in the cracks. The chert is assumed to have fractured during the compressional stage of impact-triggered earthquake waves with the fractures then opening during the dilational wave phase. Fine granular material then fell into the openings, preventing them from closing and subsequently the material was lithified. material show a variety of ejecta features, the most obvious being accretionary lapilli which have yielded quartz and feldspar grains showing planar deformation features (PDFs) and planar fractures. Planar features have not been found in larger subrounded and angular quartz and feldspar grains contained within the debrisite generally as opposed to within accretionary lapilli. This is the only site in which DVIG [devitrified vesicular impact glass], is not the most obvious ejecta feature within the debrisite. In fact, no DVIG has been observed, however carbonate and silica replaced clusters of spherules are present. Non-ejecta features include subrounded to round chert grains in carbonate cement, subcentimetre stromatolite fragments and mudstone and shale rip-ups. Chloritic, blotchy, black Gunflint Formation granules, similar in shape and size to microtektites, are present within the carbonate cement. Carbonate-replaced microtektite shapes are present but since they lack residual internal structure, it is impossible to determine if they were microtektites or carbonatereplaced Gunflint chlorite granules.” Thin sections prepared from the blasted STOP 2-3: Kakabeka Falls Provincial Park 0305738E / 5364400N; 0305178E / 5364663 (n.b. Entry/parking fee is required in Kakabeka Falls Provincial Park. Sample collecting and hammers are NOT permitted.) Two stops at Kakabeka Falls provide an opportunity to see both a thick section of Gunflint Formation rocks exposed in the gorge of the Kaministiquia River, and the basal, stromatolite-bearing units of the Gunflint unconformably overlying Neoarchean granitoid basement. This location was previously described by Pufahl et al. (2000) and Smyk (2012). Figure 45. Accretionary and armored lapilli draped unconformably over a stromatolite, composed of silicified carbonate, which was abraded to its present configuration likely by a base surge immediately preceding the deposition of the lapilli; STOP 2-3, polished surface. The gray component is primarily fine-grained, angular, fractured carbonate clasts whose individual crystals are usually <10 μm. These clasts are typically <50 μm but they may be as large as 500 μm. Quartz and feldspar grains are a minor component among the carbonate clasts within the lapilli. (caption modified from Addison and Brumpton, 2012). The park is dominated by a single, spectacular feature, Kakabeka Falls, which drops 39 m over sheer cliffs in Gunflint Formation sedimentary rocks (Figure 46). Kakabeka is an aboriginal word meaning “steep cliffs”. The age of the river gorge below the falls is still debated. If none of it existed prior to the glacial Lake Beaver Bay stage, then it is less than ca. 9700 years old. The portage around the falls contains artifacts ranging from the Paleoindian to the historic (fur trade) periods. - 30 - The falls owes its existence to the thin chert- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 are often attributed to deposition in intertidal or lagoonal subtidal environments (Pufahl et al., 2000). Figure 46. Kakabeka Falls and gorge, cut into flat-lying Gunflint Formation shales. Photo from https://hikebiketravel. com/a-trip-to-kakabeka-falls-near-thunder-bay/. carbonate bed which forms a resistant cap rock to the softer underlying shales. The river gorge is composed of a sequence of volcaniclastic shales (lessresistant, darker units) and tuffs (more-resistant, lighter coloured units). This sequence represents the major volcaniclastic horizon in the upper Gunflint Formation that is traceable to the south through the Mesabi Range. Note that shale is the predominant lithology in the Kaministiquia sections and this is, in fact, typical for the Gunflint Formation in general throughout the Thunder Bay region. Samples of lapilli tuff and reworked tuffs from the middle of the Gunflint Formation, collected by Fralick et al. (2002) at Kakabeka Falls yielded a euhedral zircon population with a U-Pb age of 1878.3 ± 1.3 Ma, believed to be nearly synchronous with the depositional age. The outcrop on the northern edge of the parking lot contains layers of banded/ribbon chert-carbonate within black, fissile shale. The alternating, dark grey chert and brown siderite-ankerite layers display slump and soft-sediment deformation features. Microscopic examination of banded chert-carbonates reveals delicate lamination in the chert which resembles the “ribbon texture” of algal mats. The interlayered carbonate bands contain complex, microspherical structures which likely resulted by nucleation from a gel state. Local thick beds of carbonaceous siderite (2-3 wt% carbon) form carbonate iron formation; contemporaneous deposition of carbon and carbonate suggests biological activity during iron deposition. Studies of the Gunflint Formation have described this type of sediment as forming in a deep, quiet water environment. However, similar carbonate sequences The rapids visible north of the highway bridge are formed by Archean granitoids. The slow-water area to the south is underlain by the Gunflint Formation. The basal conglomerate (Kakabeka member) is patchily preserved on Archean basement here. Silicified stromatolites are developed on the conglomerate or directly on the basement. This is the location from which samples collected from silicified stromatolites in the 1950’s yielded the first documented Gunflint cyanobacteria (Tyler and Barghoorn, 1954). The rock cut on Highway 590 immediately south of the intersection with Highway 11-17, west of the Kaministiquia River bridge, expose cherty carbonates at the base of the Gunflint Formation where it rests unconformably over Neorchean granitoid basement. Large-form stromatolites are developed at the unconformity (Figures 47 and 48). The stromatolitic, ribbon carbonates are abruptly overlain by a grainstone succession. Black anthraxolite veinlets and void fillings occur with vein quartz in the chert-carbonate rocks. Anthraxolite and pyrobitumen in the Gunflint Formation (Figure 49) has been noted and studied numerous researchers, including Tanton (1931), Ellesworth (1934), Goodwin (1956), Kwiatkowski (1975), Barghoorn et al. (1977), Hayatsu et al (1983), Mancuso et al. (1989), Rutter (2014), Rasmussen and Muhling (2019), and Rasmussen et al. (2021). Figure 47. Colloform stromatolite (left of hammer) in Ferich carbonate grainstones, Highway 590 exposure, STOP 2-4. The stromatolite was situated approximately 40 cm above the unconformity with Neoarchean basement granitoid rocks. Unfortunately, the stromatolite spalled from the outcrop face ca. 2016. Coin is 2.5 cm in diameter. - 31 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 49. Void-filling, conchoidal anthraxolite and quartz in sideritic Gunflint grainstone, Highway 590 exposure, STOP 2-4. of Superior lobe drift. The exposed sequence consists of approximately 6 to 7 m of well sorted, steeply-dipping sand and gravel of Superior provenance overlain by 2 to 3 m of silty Superior lobe till [Figure 50]. Clasts in the lower glaciofluvial unit consist primarily of Proterozoic metasedimentary rocks. Numerous cobbles and boulders belonging to the Gunflint Formation and Sibley Group are recognizable. Foreset beds dip steeply to the north and are likely of deltaic origin. The delta was probably built proglacially into an early phase of glacial Lake Kaministikwia. The feature therefore represents a location at which the advancing Superior Lobe stalled prior to reaching its maximum position at the Marks Moraine. Figure 48. Detailed view of the large, silicified, colloform stromatolite in Figure 47. Rasmussen et al. (2021) suggested that stromatolitic, black Gunflint cherts were saturated in syn-sedimentary oil. Thermally altered oil (pyrobitumen) occurs in the stromatolites and intercolumn sediments, fills pores and fractures, and coats detrital and diagenetic grain surfaces. Hayatsu et al. (1983) described two very distinct macromolecular materials in the Gunflint anthraxolite that suggested that the Thunder Bay area was once covered by Cretaceous or Jurassic marine sediments, similar to those documented in the Mesabi range of Minnesota. The delta is actually located within only 3 km of the Superior lobe limit and occurs at an elevation of about 375 m asl, 85 m below the maximum elevation of Lake Kaministikwia. The delta was STOP 2-5: Briggs Drive Gravel Pit 0304790E / 5369390N (n.b. Private Property, contact Township of Conmee for access permission) This stop not only highlights some interesting glacial sediments, but also provides an opportunity to examine large boulders of a variety of local rock types that have been transported by glacial ice and meltwater. This location was described by Bajc (2000): “At this stop, we will be looking at a section Figure 50. View, looking west, of steeply dipping, gravelly foreset beds of a delta constructed along the margin of the advancing Superior lobe, Briggs Drive gravel pit, STOP 2-5. Silty Superior lobe till caps the sequence. - 32 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 overridden by the Superior lobe resulting in the truncation of the foreset unit and removal of the topset beds. Several metres of silty, Superior Lobe subglacial till was deposited on top of the sands and gravels. “seven lenticular masses of brecciated, banded iron formation, in which pyrite has replaced a considerable part of the rock” (Carter 1990). The largest of these masses has a maximum width of 23 m and is 244 m long. Other discoveries include a 21-m wide body of pyrite containing magnetite and pyrrhotite and a 9 m wide by 15 m long zone of magnetite-pyrite-jasper ironstone. It is possible that the boulders found within the gravel pit [Figure 51] were derived from this area and Of particular significance is the occurrence of large angular to rounded boulders on the pit floor. The boulders were extracted from the lower glaciofluvial unit and, in some cases, do not appear to have been transported very far. Some of the larger boulders measure several metres across and still display striated surfaces. The boulders are derived from both Archean and Proterozoic source rocks. Several boulders of sulphidized iron formation and massive pyrite of Archean age were discovered in the boulder piles. One of the boulders measured over 1 m in diameter and consisted of massive pyrite and magnetite with 10 to 15% sphalerite disseminated in pyriterich sections. Sphalerite was also concentrated along fractures and adjacent to quartz veinlets throughout the rock. Two samples from the pyriterich zones returned values of: 1) 5.13% Zn, 18 ppm Cu, 19 ppm Pb, 260 ppb Au and 0.5 ppm Ag; and 2) 2.85% Zn, 16 ppm Cu, 20 ppm Pb, 245 ppb Au and 0.5 ppm Ag. A sample from the magnetiterich zone returned values of 850 ppm Zn, 25 ppm Cu, 5 ppm Pb, 25 ppb Au and <0.2 ppm Ag. A second sulphidized iron formation boulder measuring approximately 0.5 m in diameter and consisting almost exclusively of pyrite, returned values of 140 ppm Zn, 8 ppm Cu, 11 ppm Pb, 710 ppb Au and <0.2 ppm Ag. There are two possible source areas for the boulders. Superior lobe striae in the immediate vicinity of the pit are oriented at 320 to 330° Az. If the boulders were eroded and transported by Superior ice, then there is a 5 km window towards the southeast from which they could have been derived. Proterozoic metasedimentary rocks outcrop beyond the 5 km limit. Alternatively, the boulders could have initially been eroded by northern ice from a source to the north-northeast of the pit then remobilized by the Superior lobe. Exploration work during the early 1900s along the lower reaches of Brule Creek, 4 to 5 km northnortheast of the gravel pit, by B.L. Morrison, the Davis Sulphur Company and General Chemical Company resulted in the discovery of Figure 51. Pile of oversized boulders of a variety of local Archean and Proterozoic rock types, Briggs Drive gravel pit, STOP 2-5. Reddish silty Superior lobe till is visible at the top of the pit wall. Photo taken ca. 1999. that sphalerite was not recognized in the rock. It is not yet clear whether the sulphides indicate proximity to a VMS style zone of mineralization. Further work is required to assess the mineral potential of this area.” STOP 2-6: Temiskaming sedimentary rocks, Finmark 293709E / 5383903N This stop, having long been a “must-see” for local geology students, has benefited from new exposures - 33 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 on the south side of Highway 11-17 that were created during highway expansion and ballast quarry development ca. 2019. The outcrops on both sides of the highway expose excellent examples of clastic Neoarchean “Temiskaming-type” metasedimentary rocks (ca. 2690-2695 Ma) of the Shebandowan assemblage that still display many primary sedimentary features that provide clues as to the depositional environment. The Timiskaming-type successions of the SGB are interpreted to have been deposited in subaerial to shallow marine environments (Shegelski, 1980). Highway 11-17 by Koebernick and Fralick (1995) and Koebernick (1996) documented sedimentary structures and bed sequences consistent with shallow water, coastal sedimentation in three major depositional environments: tidal strandline, the shoreface, and the offshore (e.g. Figure 52). Koebernick (1996) noted: “The three environments and associated sub-environments record processes reflective of differing current activity which controlled and The ballast quarry immediately to the south has been developed in mafic, Neoarchean metavolcanic rocks of the Greenwater assemblage (ca. 2720 Ma) which presumably underlie the clastic rocks unconformably or are in fault contact with them. Parker (1980) noted that reversals of top directions and the presence of both easterly and westerly plunging minor folds, suggest that one or more episodes of folding have occurred. Detrital zircon geochronology by Corfu and Stott (1998) confirmed that the metasedimentary rocks in the Finmark area (<2691+3 Ma) and in the southern part of Adrian Township (<2700+4 Ma) are younger than the Greenwater assemblage. Because of the remarkable preservation of primary sedimentary features, this stop has been the focus of study for many years, including theses by Parker (1980) and Koebernick (1996). The metasedimentary sequence here comprises interbedded sandstonesiltstone-mudstone sequences which alternate with thick deposits of cross-stratified sandstones (Parker, 1980). The interlayered sequences contain many of the primary sedimentary structures characteristic of tidal flat deposits, such as flaser bedding, lenticular bedding, herringbone cross-bedding, mud cracks, mud drapes, and bipolar paleocurrent indicators. Parker (1980) noted that the clastic sedimentary rocks are composed of feldspar, rock fragments, quartz, and some mafic minerals. Modal analysis revealed that most of the sandstones in the area are arkosic arenites. Lithic fragments are felsic to intermediate and predominantly calc-alkalic volcanics, with lesser amounts of other igneous grains and sedimentary rock fragments. This led Parker (1980) to suggest that the clastic rocks probably represent immature detritus from proximal volcanic centers. A detailed study of the “Temiskaming-type” clastic rocks at this location and along this section of Figure 52. Stacked, trough cross-bedded sandstone beds with tangential foreset laminae, south side of Highway 1117, STOP 2-6. Ripples are preserved on bedding surfaces (lower photo). - 34 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 53. Dark alteration holes defining herringbone cross bedding in sandstone, north side of Highway 11-17, STOP 2-6. influenced deposition. The tidal environment was dominated by bidirectional tidal currents [Figure 53]. Deposition In the shoreface was predominated by unidirectional wave-produced currents which overprinted prevailing tidal current activity, in the distal portions of the shoreface environment though, deposition was once again controlled by tidal currents. In the offshore, deposition was controlled by storm currents which generated distinctive beds of hummocky cross-stratification. The tidal environment is composed of many sedimentary structures similar to those present in Phanerozoic and present-day tidal sequences. In the tidal flat sub-environment, vertical sequences of flaser, lenticular, wavy and coarsely interlayered bedding reflect current velocity fluctuations Intimately tied to spring - neap tidal cycles. The tidal channel sub-environment lacks many of the features characteristic of tidal channels described in the literature; such as extensive point bar development. Instead, the tidal channels of the study area appear to represent sequences deposited in relatively straight channels. Migration of sand waves and dune fields deposited the cross-stratified lithofacies of the shoreface environment. Similar to a highenergy, non-barred coastline, the proximal portion of the shoreface lacks any evidence of beach development. Instead, the shoreface records a rapid and discontinuous transition from the tidal strandline environment. Hummocky cross-stratification (HCS) [Figure 54], parallel- Figure 54. Hummocky cross-stratification, which is only formed and preserved by storm waves in depths between fair weather wave base and storm wave base. laminated and massive sandstone beds as well as siltstone and mudstone beds typify the offshore environment [Figure 55]. The HCS differs greatly in thickness and internal structure from HCS described in the literature. The HCS in the study area reflects restricted and/or variable sediment supply and flow conditions. A paleotidal range was determined from the sediments of the tidal environment. The range indicated a mesotidal Figure 55. Thinning- and fining-upward sequence, showing transition from medium-bedded sandstones to a mudstone/ siltstone-dominated package with thin sandstone interbeds, south side of highway, STOP 2-6. This likely represents deepening of the water, going from nearshore coarse-grained sands moved around on the bottom as dunes by fair-weather waves and currents, to deeper water deposits below fairweather wave base, representing tempestites (i.e. hummocky cross-stratified storm deposits and graded beds formed below storm wave base by the same geostrophic flows that formed hummocky cross-stratification in shallower water; P. Fralick, personal communication, 2026). - 35 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 56. Stratigraphic column of outcrops on north side of Highway 11-17, STOP 2-6, showing primary sedimentary features and paleocurrent measurements (P. Fralick, personal communication, 2026). environment and is comparable to Precambrian tidal ranges reported in the literature. Tidal rhythmites, present on the tidal flats, suggest a length of 26 days for the Neoarchean lunar month. Currents which deposited the tidal rhythmites produced both semi-diurnal and diurnal sediment sequences [Figure 56].” reversals. Evidence of shearing and brittle deformation, including quartz-carbonate veining, can also be observed, especially in the easternmost portions of the outcrop exposure on the south side of the highway (Figures 57 and 58). As noted above, in spite of the remarkable preservation of sedimentary structures, the Shebandowan assemblage sedimentary rocks in this area have experienced tectonic deformation and display features that include minor folds and younging Bedding-cleavage relationships indicative of folding are visible in the outcrops at this location. Bedding orientations vary from approximately 325/70 northeast on the north side of the highway to 110/70 south on the south side. The cleavage-bedding relationship is most easily observed in the thin-bedded mudstones and siltstones south of the highway, where the cleavage - 36 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 57. Quartz-carbonate veining in altered and deformed Figure 58. Photo illustrating small-scale folds, shears and rocks at the east end of the outcrop area on the south side of sigmoidal tension fractures in thin-bedded siltstone and mudstone at STOP 2-6. Highway 11-17 at STOP 2-6. orientation is approximately 085/85 south. The change in bedding orientation relative to cleavage, when combined with northward-younging indicators (e.g., graded bedding), indicate the probable presence of an anticline axis a short distance to the north. This interpretation is consistent with previous geological mapping completed by Carter (1985). The structures observed here may have developed during the same tectonic events that gave rise to orogenic gold mineralization at the nearby Eureka Gold Deposit, which is currently being explored by Delta Resources Limited. Eureka is located approximately 4 km to the west-northwest of here, and the deposit occurs within a structural corridor known as the “Shebandowan structural zone.” Gold mineralization at Eureka also has a close spatial association with the unconformity between the Greenwater and Shebandowan assemblages. Delta Resources has outlined the Eureka Gold Deposit over a 2.5-kilometre strike length, and to a vertical depth of 300 metres. Mineralization occurs over true widths ranging from 10 to 100 metres, and the deposit remains open in all directions. Gold is hosted by multiple generations of quartzankerite-pyrite veinlets that generally range from 1 mm to 10 cm wide and cross-cut multiple lithologies. Wider quartz veins up to 4.5 metres wide, and goldbearing silica-flooding zones are also found within the deposit. Host rock alteration is characterized by intense, texture-destructive ankeritization, silicification, albitization and sericitization combined with trace to 2% disseminated pyrite and trace arsenopyrite. The altered rocks typically contain anomalous gold. Feldspar-phyric monzonite to diorite dikes also have a close spatial association with the mineralization and are locally altered (https://www.deltaresources.ca/ delta-1-gold-project/). STOP 2-7: Pillowed Basalt, Mud Lake 315029E / 5376770N No trip would be complete without pillowed basalt! These roadside exposures along Highway 102 near Mud Lake display tholeiitic, mafic to intermediate volcanic Figure 59. Pillowed basalt flow, STOP 2-7, showing wellpreserved, close-packed pillows and hyaloclastite-filled inter-pillow spaces. - 37 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 rocks of the Neoarchean Greenwater assemblage, situated near the Quetico–Wawa subprovince boundary (Brown, 1995; Brown and Fogal, 1995). In this area, the degree of pillow preservation varies considerably. Figure 60. Close-up of pillow, STOP 2-7, showing contact of chilled upper selvage (large dashed line). However, well-formed, close-packed pillows, ranging from 10 by 15 cm to 30 by 60 cm in size, are locally preserved (Figure 59). Where discernible, younging directions within this unit are consistently to the north. Carbonate-filled amygdules, generally less than or equal to 1 mm in size and constituting up to 10% of the pillows by volume, are commonly present, radiating outward from the core of the pillows (ibid; Figure 60). North-younging, pillowed flows exposed at STOP 2-7 display well-preserved primary features, including autoclastic breccias (e.g. pillow breccia, inter-pillow hyaloclastite; Figure 61), close packing and pillow cusps, and calcite-filled amygdules. Larger, ovoid amygdules occur sparingly in the cores of pillows, while smaller, more numerous, pipe-like amygdules tend to be concentrated near pillow selvages. Pillows typically range between 25 cm and ~1m in size. The Mud Lake Cu-Zn occurrence (Ontario Mineral Inventory, https://www.geologyontario.mines.gov. on.ca/mineral-inventory/MDI000000002310) can be observed in a roadside outcrop located a few hundred metres northwest of STOP 2-7 along the highway. Pyrite, minor chalcopyrite and rare sphalerite are finely disseminated throughout, and adjacent to, a sericitized northeast-trending zone of shearing hosted within chemical metasedimentary rocks interbedded with felsic and intermediate pyroclastic metavolcanic rocks (Brown, 1995; Brown and Fogal, 1995). The mineralization was first uncovered during construction along Highway 102 in the mid-1970s. A grab sample collected in 1975 by staff of the Resident Geologist’s office, Thunder Bay, yielded values of 0.24% Cu, 0.87% Zn, 0.12 ounces Ag per ton and 0.005 ounces Au per ton (Fenwick and Scott, 1976). The felsic metavolcanic rock unit adjacent to the copper- and zinc-mineralized horizon yielded a U-Pb age of 2718+3 Ma (Corfu and Stott, 1998). A magnetic lamprophyre dyke, < 2m wide, crosscuts the pillowed flows at 065˚-080˚ and dips steeply north. Some of these late Neoarchean intrusions in this area were classified as kersantites (i.e. calc-alkaline, biotiteplagioclase-bearing lamprophyre) by Brown (1995). ACKNOWLEDGEMENTS Figure 61. Isolated-pillow breccia, STOP 2-7, showing amoeboid to angular pillow fragments in hyaloclastite-rich matrix. The authors would like to acknowledge the support and guidance of many former and present colleagues at the Ontario Geological Survey, Lakehead University and the Geological Survey Canada over the past several decades. This field guide has benefitted greatly from the comments, information and suggestions provided by Dr. Phil Fralick (Lakehead University), Riku Metsaranta (Ontario Geological Survey) and Dr. Wouter Bleeker (Geological Survey of Canada). Pete - 38 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Hollings assembled the final manuscript. We would also like to thank property owners who have provided permission to access several sites for the purposes of this field trip. REFERENCES Addison, W.D. and Brumpton, G.R. 2012. Field trips 1 & 13 Sudbury impactoclastic debrisites at Thunder Bay; In; Hollings, P., MacTavish, A. and Addison, W. (Eds.), Institute on Lake Superior Geology Proceedings, 58th Annual Meeting, Thunder Bay, Ontario, Part 2 - Field trip guidebook, v.58, part 2, 2-26. Addison, W.D., Brumpton, G.R., Vallini, D.A., McNaughton, N.J., Davis, D.W., Kissin, S.A., Fralick, P.W. and Hammond, A.L. 2005. Discovery of distal ejecta from the 1850 Ma Sudbury impact event; Geology, v.33, p.193-196. Addison W.D., Brumpton, G.R., Davis, D.W., Fralick, P.W. and Kissin. S.A. 2010. Debrisites from the Sudbury impact event in Ontario, north of Lake Superior, and a new age constraint: Are they base-surge deposits or tsunami deposits? Geological Society of America Special Papers, 2010, 465, p. 245-268. Barghoorn, E.S., Knoll, A.H., Dembicki, H., Jr., and Meinschein, W.G. 1977. 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Geology of Forbes and Conmee townships; Ontario Geological Survey, Open File Report 5726, 188p. Carter, M.W., McIlwaine, W.H. and Wisbey, P.A. 1973: Nipigon-Schreiber, Geological Compilation Series, Thunder Bay District; Ontario Division of Mines Map Number 2232, at a scale of l inch to 4 miles or1:253,440. Cheadle, B.A. 1986. Alluvial-playa sedimentation in the lower Keweenawan Sibley Group, Thunder Bay District, Ontario; Canadian Journal of Earth Sciences, 23, pp.527–542. Corfu, F. and Stott, G.M. 1998. Shebandowan greenstone belt, western Superior Province: U-Pb ges, tectonic implications, and correlations; GSA Bulletin 110, pp.1467-1484. Davis, D.W. and Green, J.C. 1997. Geochronology of the North American Midcontinent rift in western Lake Superior and implications for its geodynamic evolution; Canadian Journal of Earth Sciences, v.34, pp.476-488. Davis, D.W. and Sutcliffe, R.H. 1985. U-Pb ages from the Nipigon Plate and northern Lake Superior; Bulletin of the Geological Society of America, v. 96, p. 15721579. Ellesworth, H. V. 1934. Nickeliferous and uraniferous anthraxolite from Port Arthur, Ontario; American Mineralogist, Vol. 19, pp. 426-248. Fralick, P.W. and Riding, R. 2015. Steep Rock Lake: sedimentology and geochemistry of an Archean carbonate platform. Earth Science Reviews, v.151, pp.132–175. Fralick, P.W., Davis, D.W. and Kissin, S.A. 2002. The age of the Gunflint Formation, Ontario: single zircon U-Pb age determinations from reworked volcanic ash; Canadian Journal of Earth Sciences, v.39, no.7, p.1085-1091. Fralick, P.W., Smyk, M.C. and Metsaranta, R. 2012. Field Trip 2 – Geology of the Sibley Peninsula; In; - 39 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Hollings, P., MacTavish, A. and Addison, W. (Eds.), Institute on Lake Superior Geology Proceedings, 58th Annual Meeting, Thunder Bay, Ontario, Part 2 Field trip guidebook, v.58, part 2, 27-55. River–Disraeli Lake area, Nipigon Embayment, northwestern Ontario: lithogeochemical, assay and compilation data; Ontario Geological Survey, Miscellaneous Release—Data 133. Franklin, J.M. 1978. The Sibley Group, Ontario. In Rubidium–strontium isotopic age studies, Report 2. Edited by R.K. Wanless and W.D. Loveridge. Geological Survey of Canada, Paper 77-14, pp. 31– 34. Hayatsu, R., Winans, R. E., Newman, D. S., Mancuso, J.J. and Seavoy, R.E. 1983: Correlations between the chemical and the geologic origins of anthraxolite from the Gunflint Formation, Thunder Bay, Ontario; Economic Geology, Vol. 78, 1983, pp. 175-180. Franklin, J.M., Kissin, S.A., Smyk, M.C. and Scott, S.D. 1986. Silver deposits associated with the Proterozoic rocks of the Thunder Bay District, Ontario; Canadian Journal of Earth Sciences, v.23, pp.1576-1591. Heaman, L.M. and Easton, R.M. 2006. Preliminary U/ Pb geochronology results: Lake Nipigon Region Geoscience Initiative. Ontario Geological Survey, Miscellaneous Release-Data 191, 79p. Franklin, J.M., McIlwaine, W.H., Poulsen, K.H., and Wanless, R.K. 1980. Stratigraphy and depositional setting of the Sibley Group, Thunder Bay District, Ontario, Canada. Canadian Journal of Earth Sciences, v.17, p.633–651. Heaman, L.M., Easton, R.M., Hart, T.R., Hollings, P., MacDonald, C.A. and Smyk, M. 2007. Further refinement to the timing of Mesoproterozoic magmatism, Lake Nipigon Region, Ontario. Canadian Journal of Earth Sciences, v.44, no.8, p.1055-1086. Franklin, J.M., McIlwaine, W.H., Shegelski, R.J., Mitchell, R.H. and Platt, R.G. 1982. Proterozoic geology of the northern Lake Superior area; Field Trip Guidebook, GAC-MAC Annual Meeting, Winnipeg, 71p. Hill, M. L. and Smyk, M.C. 2005. Penokean fold-andthrust deformation of the Paleoproterozoic Gunflint Formation near Thunder Bay, Ontario; 51st Institute on Lake Superior Geology, Annual Meeting, Nipigon, Ontario, May 2005, Proceedings Volume 51, Part 1, p.26. Fenwick, K.G. and Scott, J.F., 1976. 1975 Report of the North Central Regional Geologist; p. 39-54 in Annual report of the Regional and Resident Geologists, 1975, edited by C.R. Kustra, Ontario Division of Mines, Miscellaneous Paper 64, 146p. Geul, J.J.C. 1970. Geology of Devon and Pardee Townships and the Stuart Location; Ontario Department of Mines, Geological Report 87, 52 p. Geul, J.J.C 1973. Geology of Crooks Township, Jarvis and Prince Locations, and Offshore Islands, District of Thunder Bay; Ontario Department of Mines, Geological Report 102, 46 p. Goodwin, A.M. 1956. Facies relations in the Gunflint Iron Formation; Economic Geology, v.51, pp.565–595. Hamilton, J. S. 1996. Pleistocene landscape features and Plano archaeological sites upon the Kaministiquia delta, Thunder Bay District; Lakehead University Monograph in Anthropology #1, 112p. Hart, T.R and MacDonald, C.A. 2007. Proterozoic and Archean geology of the Nipigon Embayment: Implications for emplacement of the Mesoproterozoic Nipigon diabase sills and mafic to ultramafic intrusions; Canadian Journal of Earth Sciences, v.44, no.8, p.1021-1040. Hart, T.R., MacDonald, C.A., Hollings, P., and Richardson, A., 2005. Proterozoic intrusive rocks of the Nipigon Embayment and Midcontinent Rift. In, T.O. Tormanen and T.T Alapieti, 10th International platinum Symposium Extended Abstracts, Geology Survey of Finland, 365-368. Hart, T.R. and Magyarosi, Z. 2004. Northern Black Sturgeon Hollings, P., Cundari, R., Pulchalski, R. and Smyk, M.C. 2011. Geochemistry of Midcontinent Rift- related mafic intrusions, Thunder Bay area; Ontario Geological Survey, Miscellaneous Release—Data 261 – Revised. Hollings, P. and Smyk, M.C. 2008. Whatever happened to the Logan sills? Ongoing research into the geochemistry of Midcontinent Rift-related mafic intrusive rocks south of Thunder Bay: 54th Institute on Lake Superior Geology, Annual Meeting, Marquette, Michigan, May 2008, Proceedings Volume 54, Part 1, p.36-37. Hollings, P., Hart, T., Richardson, A., and MacDonald, C.A. 2007a. Geochemistry of the Mesoproterozoic intrusive rocks of the Nipigon Embayment, northwestern Ontario: evaluating the earliest phases of rift development; Canadian Journal of Earth Sciences, v.44, no.8, p.1087-1110. Hollings, P.N., Smyk, M.C. and Hart. T. 2007b. Geochemistry of Midcontinent Rift-related mafic dykes and sills near Thunder Bay: New insights into geographic distribution and the geochemical affinities of Nipigon and Logan sills and Pigeon River and other dykes; 53rd Institute on Lake Superior Geology, Annual Meeting, Lutsen, Minnesota, May 2007, Proceedings Volume 53, Part 1, p.40-41. Hollings, P.N., Smyk, M.C. Heaman, L.M. and Halls, H. 2010. The geochemistry, geochronology and paleomagnetism of dikes and sills associated with the Mesoproterozoic Midcontinent Rift near Thunder Bay, Ontario, Canada; Precambrian Research 183 - 40 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 thesis, Lakehead University, Thunder Bay, ON, 103 p. (2010) 553–571. Hughes, A. 2016. Petrology and geochemistry of the McKenzie Granite, northwestern Ontario; unpublished H.B.Sc. thesis, Lakehead University, Thunder Bay, Ontario, 78p. Hughes, A., Hollings, P., Smyk, M.C., Puumala, M.A. and Campbell, D.A. 2017. Petrology and geochemistry of the Neoarchean McKenzie Granite, northwestern Ontario; Ontario Geological Survey, Miscellaneous Release – Data 349, 14p. Jones R., Marcelissen, R., and Fralick, P., 2022. Sedimentology and stratigraphy of a large prevegetation deltaic complex; Frontiers in Earth Science 10, 27p., 875838. Kissin, S.A. 1992. Five-element (Ni-Co-As-Ag-Bi) veins; Geoscience Canada, v.19, pp.113-124. Koebernick, C.A. 1996. Neoarchean coastal sedimentation in the Shebandowan Group, Northwestern Ontario’ unpublished M.Sc. thesis, Lakehead University, Thunder Bay, ON, 248p. Koebernick, C.F. and Fralick, P. 1995. Neoarchean coastal sedimentation in the Shebandowan Group, northeastern Ontario; in 41st Annual Meeting, Institute on Lake Superior Geology, Proceedings Volume 41, Part 1 - Program and Abstracts, pp. 3132. Koroscil, J.P.J. 2013. Deformation of the Animikie Group north of Lake Superior; unpublished H.B.Sc. thesis; Lakehead University, Thunder Bay, Ontario. Krogh, T.E., Davis, D.W., Corfu, F., 1984. Precise U-Pb zircon and baddeleyite ages for the Sudbury area. In: Pye, E.G. (Ed.), The Geology and Ore Deposits of the Sudbury Structure, Ontario Geological Survey, Special Volume 1, pp. 431–446. Kronberg, B.I. and Fralick, P.W. 1992. Geochemical alteration of felsic Archean rocks by Gunflint Formation-derived fluids, Quetico - Superior region, northwest Ontario; Canadian Journal of Earth Sciences, v. 29, pp.2610-2616. Kup, S., Tsujita, C.J., Jin, J., Shuster, J., Metsaranta, R.T. and Kurcinka, C.E. 2025. Microfossil preservation in the Paleoproterozoic Gunflint Formation: Comparative study of the Pass Lake and the classic Schreiber Beach localities, northern Ontario; in Summary of Field Work and Other Activities, 2025, Ontario Geological Survey, Open File Report 6421, p.9-1 to 9-14. Kustra, C.R., McIlwaine, W.H., Fenwick, K.G. and Scott, J.F. 1977. Proterozoic rocks of the Thunder Bay area, northwestern Ontario; Field Trip Guidebook, 23rd Annual I.L.S.G. Meeting, Thunder Bay, 47p. Kwiatkowski, D. 1975. Geology and geochemistry of the Kakabeka Falls anthraxolite; unpublished H.B.Sc. Landman, M. 2021. Archean orogenesis to Proterozoic rifting: A structural history of Pass Lake, Thunder Bay, Ontario; unpublished H.B.Sc. thesis, Lakehead University, Thunder Bay, Ontario. Machado, A.B., 1987. On the origin and age of the Steep Rock buckshot, Ontario, Canada; Chemical Geology, v. 60, pp. 337–349. MacNeish, R.S. 1952. A possible early site in the Thunder Bay district, Ontario, Annual Report of the National Museum of Canada for the Fiscal year 1950–51. National Museum of Canada Bull 126, p 25, pp. 27–28. Magnus, S. 2012. An investigation of the assimilation hypothesis in the Navilus sill, Thunder Bay, Ontario’ unpublished H.B.Sc. thesis, Lakehead University, Thunder Bay ON. Magnus, S., and Kissin, S., 2010. Assimilation and petrogenesis in the Navilus and Terry Fox sills, Thunder Bay, Ontario; in Institute on Lake Superior Geology, Proceedings and Abstracts, v. 56, part 1, p. 36-37. Mancuso, J.J., Kneller, W.A., and Quick, J.C. 1989. Precambrian vein pyrobitumen: evidence for petroleum generation and migration 2 Ga ago. Precambrian Research, v. 44, pp.137–146. Maric, M. 2006. Sedimentology and sequence stratigraphy of the Paleoproterozoic Rove and Virginia formations, southwest Superior Province; unpublished M.Sc. thesis, Lakehead University, Thunder Bay ON. McIlwaine, W.H. 1975. McTavish Township (southern half), District of Thunder Bay; Ontario Division of Mines, Preliminary Map P.990, scale 1:15 840. Metsaranta, R.T. 2022. Highlights of bedrock geology mapping in the Quetico Subprovince, north of Thunder Bay, northwestern Ontario; in Summary of Field Work and Other Activities, 2022, Ontario Geological Survey, Open File Report 6390, p.9-1 to 9-9. Metsaranta, R.T and Kurcinka, C.E. 2022. Reconnaissance bedrock geology mapping of the Animikie Basin and spatially associated Midcontinent Rift–related igneous rocks, Thunder Bay area, northwestern Ontario: A project introduction; Summary of Field Work and Other Activities, 2022, Ontario Geological Survey, Open File Report 6390, p.11-1 to 11-13. Metsaranta, R.T. and Walker, J.A. 2019. Precambrian geology of western McGregor Township and adjacent areas, northeast of Thunder Bay; in Summary of Field Work and Other Activities, 2019, Ontario Geological Survey, Open File Report 6360, p.11-1 to 11-10. Miller, J.D., Green, J.C. and Severson, M.J. 2002. - 41 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Terminology, nomenclature and classification of Keweenawan igneous rocks of northeastern Minnesota; in Geology and mineral potential of the Duluth Complex and related rocks of northeastern Minnesota; Minnesota Geological Survey, Report of nvestigations Moorhouse, W.W. 1960. Gunflint Iron Range in the vicinity of Port Arthur; Ontario Department of Mines, v.69(7): pp.1-40. Oja, R.V. 1967. Geochemical investigations of the Thunder Bay silver area; in Proceedings, Symposium on Geochemical Prospecting, Ottawa Ontario, 1967; Geological Survey of Canada, Paper 66-54, pp.211221. Parker, J.R. 1980. The Structure and Environment of Deposition of the Finmark Metasediments, Thunder Bay, Ontario; unpublished H.B.Sc. thesis, Lakehead University, Thunder Bay, ON Phillips, B. 2004. Of moraines, lake floors, deltas and shorelines: A brief summary of the deglaciation of the Kaministiquia embayment, Thunder Bay, Ontario; unpublished report, World Wide Website, http:// www.lakeheadu.ca/~geogwww/phillips/FOP%20 page_4.htm (accessed 2004). Phillips, B., Hill, C., Fralick, P. and Ross, B. 1994. Postglacial shorelines and Paleoindian migration along the northwestern shore of Lake Superior; Field Trip Proceedings of the 58th ILSG Annual Meeting -Part 2 Guidebook, 13th Biennial meeting of AMQUA, Minneapolis, MN. Phillips, B., Stewart, J., Hamilton, S., Julig, P. and Ross, B. 2000. Geoarchaeology of the Thunder Bay area; 46th Institute on Lake Superior Geology, Thunder Bay, Ontario, Field Trip Guidebook, 40p. Puchalski, R. 2010. The petrology and geochemistry of the Riverdale sill. Unpublished H.B.Sc. thesis, Lakehead University, Thunder Bay, ON. Pufahl, P., Fralick, P. and Scott, J.F. 2000. Geology of the Paleoproterozoic Gunflint Formation; in Institute on Lake Superior Geology, 46th Annual Meeting, Field Trip Guidebook. Purucker, M. 1983: Time of Formation of Soft Iron Ore on the Gunflint and Mesabi Ranges (Ontario, Canada and Minnesota, U.S.A.); Economic Geology, Vol. 78, 1983, pp. 502-506. Puumala, M.A., Campbell, D.A., Tims, A., Debicki, R.L., Pettigrew, T.K. and Brunelle, M.R. 2015. Report of Activities 2014, Resident Geologist Program, Thunder Bay South Regional Resident Geologist Report, Thunder Bay South District; Ontario Geological Survey, Open File Report 6303, 75p. Pye, E.G. 1969. Geology and scenery, north shore of Lake Superior; Ontario Department of Mines, Geological Guidebook No.2, 148p. Rasmussen, B., and Muhling, J.R. 2019. Evidence for widespread oil migration in 1.88 Ga Gunflint Formation; Geology, v.4, pp.899–903. Rasmussen, B., Muhling, J.R. and Fischer, W.W. 2021. Ancient oil as a source of carbonaceous matter in 1.88-billion-year-old Gunflint stromatolites and microfossils; Astrobiology, v.21, Number 6, 2021; DOI: 10.1089/ast.2020.2376. Reid-Sharp, R. 2016. Characterizing Deformation of Gunflint Formation in Contact with the Archean Basement; unpublished H.B.Sc. thesis, Lakehead University, Thunder Bay, Ontario. Rezka, R. 1987. Shallow marine, storm-dominated deposits of the Shebandowan–Wawa greenstone belt; unpublished BSc thesis, Lakehead University, Thunder Bay, Ontario, 79p. Rogala, B. 2003. The Sibley Group: a lithostratigraphic, geochemical, and paleomagnetic study. Unpublished M.Sc. thesis, Lakehead University, Thunder Bay, Ontario, 254 p. Rogala, B., Fralick, P.W., and Metsaranta, R. 2005. Stratigraphy and sedimentology of then Mesoproterozoic Sibley Group and related igneous intrusions, northwestern Ontario: Lake Nipigon Region Geoscience Initiative. Ontario Geological Survey, Open File Report 6174, 87 p. Rogala, B., Fralick, P.W., Heaman, L.M., and Metsaranta, R. 2007. Lithostratigraphy and chemostratigraphy of the Mesoproterozoic Sibley Group, northwestern Ontario. Canadian Journal of Earth Sciences, v.44. Rutter, A.M. 2014. Analysis of anthraxolite and Precambrian carbonates of Kakabeka Falls, Ontario, Canada; American Geophysical Union, Fall Meeting 2014, abstract id. B41B-0040, Pub Date: December 2014 Bibcode: 2014AGUFM.B41B0040R. Scott, J. 1990. Geology of MacGregor Township; Ontario Geological Survey, Open File Report 5719, 82p. Sergiades, A.O. 1968. Silver cobalt calcite vein deposits of Ontario; Ontario Department of Mines, Mineral Resources Circular 10, 498p. Shegelski, R.J., 1980. Archean cratonization, emergence and red bed development, Lake Shebandowan area, Canada. Precambrian Research 12, pp.331-347. Shegelski, R.J. 1982. The Gunflint Formation in the Thunder Bay area; in Franklin, J.M. ed, Field Trip Guidebook 4: Winnipeg, Manitoba; Geological Association of Canada, p.14-31. Sindol, G.P., Babechuk, M.G., Petrus, J.A. and Kamber, B.S. 2020. New insights into Paleoproterozoic surficial conditions revealed by 1.85 Ga corestonerich saprolith; Chemical Geology, v.545, 5 - 42 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 July 2020, 119621, chemgeo.2020.119621. https://doi.org/10.1016/j. Smith, J.W., Bleeker, W. and Hamilton, M. 2025. The 1093 Ma Crystal Lake Intrusion: A nickel-copper mineralized intrusion emplaced during the younger southwest–northeast rift phase of the Midcontinent Rift (North America); GSA Bulletin, http://pubs. geoscienceworld.org/gsa/gsabulletin/article-pdf/ doi/10.1130/B37649.1/7366228/b37649.pdf. Smith, A.R. and Sutcliffe, R.H. 1989. Precambrian geology of Keweenawan intrusive rocks in the Crystal LakePigeon River area: Ontario Geological Survey, Map P.3139, scale 1:50 000. Smyk, M.C. 2012. Field Trip 5 – Guide to the Thunder Bay area; In; Hollings, P., MacTavish, A. and Addison, W. (Eds.), Institute on Lake Superior Geology Proceedings, 58th Annual Meeting, Thunder Bay, Ontario, Part 2 - Field trip guidebook, v.58, part 2, 74-81. Smyk, M.C and Franklin, J.M. 2007. A synopsis of mineral deposits in the Archean and Proterozoic rocks of the Lake Nipigon Region, Thunder Bay District, Ontario; Canadian Journal of Earth Sciences, v.44, pp.10411053, doi:10.1139/E07-013. Smyk, M. and Hollings, P., 2007. Midcontinent rift-related mafic intrusion north of the international border; Proceedings of the Institute on Lake Superior Geology v. 53: pp.53-80. Smyk, M.C. and Hollings, P. 2009. Geochemistry of Midcontinent Rift-related mafic intrusions, Thunder Bay area; Ontario Geological Survey, Miscellaneous Release-Data 261. Sun, S.S., and McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In Magmatism in the ocean basins. Geological Society, Special Publication No.42, 313-345. Sutcliffe, R.H. 1989. Mineral variation in Proterozoic diabase sills and dykes at Lake Nipigon, Ontario; Canadian Mineralogist, v.27, p.67-79. Tanton, T.L. 1931. Fort William and Port Arthur, and Thunder Cape map-areas, Thunder Bay District, Ontario; Geological Survey of Canada, Memoir 167, 222p. Tyler, S.A. and Barghoorn, E.S., 1954. Occurrence of structurally preserved plants in Precambrian rocks of the Canadian Shield; Science v. 199, p.606-608. Williams, H.R. 1991. Quetico Subprovince; in Geology of Ontario, Ontario Geological Survey, Special Volume 4, pt.1, p.383-403. Williams, H.R., Stott, G.M., Heather, K.B., Muir, T.L. and Sage, R.P. 1991. Wawa Subprovince; in Geology of Ontario, Ontario Geological Survey, Special Volume 4, p.485-539. Yip, C.I., 2016. Sedimentology and geochemistry of regressive and transgressive surfaces in the Gunflint Formation, northwestern Ontario; unpublished M.Sc. thesis, Lakehead University, Thunder Bay ON, 321 p. Zaniewski, K., Phillips, B. and Dean, F. 2020. Northwestern Ontario: The Thunder Bay region; February 2020; DOI:10.1007/978-3-030-35137-3_6; In book: Landscapes and Landforms of Eastern Canada, pp.159-177. Smyk, M.C., Hollings P. and Heaman, L.M. 2006. Preliminary investigations of the petrology, geochemistry and geochronology of the St. Ignace Island Complex, Midcontinent Rift, northern Lake Superior, Ontario; Institute on Lake Superior Geology, 52nd Annual Meeting, Sault Ste. Marie, ON, Program with Abstracts, v. 52, p.61-62. - 43 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Trip 2 - Geology of the Quetico Subprovince and Shebandowan greenstone belt north of Thunder Bay Riku Metsaranta and Gaetan Launay Earth Resources and Geoscience Mapping Section, Ontario Geological Survey, Sudbury, Ontario, P3E 6B5 Introduction This field trip examines the geology of the southern Quetico Subprovince (QS) and its tectonically intercalated contact with the Shebandowan greenstone belt (SGB) north and west of the City of Thunder Bay. Much of the content of this guidebook is informed by a multiyear, 1:50 000 scale bedrock mapping project that is being carried out in the area by the Ontario Geological Survey. The area encompassed by this guidebook represents the southern half of the multiyear bedrock mapping project area (see Figure 1). At the time of this field trip, a new bedrock geology map of the southern half of the project area and associated data are in preparation. Fieldwork on the northern half of the larger project area should be completed during the summer of 2026. In total, the new mapping will cover an area of approximately 4200 km2 of which approximately 70% had never been mapped at the 1:50 000 scale prior to this work. Some of the results of this bedrock mapping are summarized in interim publications (Metsaranta 2015; Metsaranta and Walker 2019; Metsaranta and Hamilton 2020, Metsaranta and Kamo 2021, Metsaranta 2022, Launay and Metsaranta 2023, Launay and Metsaranta 2024). The field trip will focus on the Archean geology of the area depicted on Figure 1. Although this is a oneday field trip, we have included 15 stops dispersed over a large area. We will not be able to visit all stops in one day. The order of the stops is organized from west to east in the SGB, followed by a south to north traverse along Highway 527 across the QS. Stops are labelled as “Optional” or “Planned”. “Planned” outcrops are the stops we will endeavour to visit during the field trip. Optional stops are included to put into perspective many of the “Planned” stops. As they are easily accessible, participants can visit these “Optional” outcrops on their own. As we are attempting to visit a high number of outcrops over a large area in one day, time spent on each outcrop may be limited. UTM coordinates used throughout the guidebook are NAD 83 Zone 16. Background Regional Geological Context The Quetico Subprovince is a vast geological entity that extends, at minimum, from central Minnesota to western Quebec. In “subprovince-style” subdivisions of the Superior Province (e.g. Card and Cielieski 1986, Williams 1991) the QS is bounded to the north by the Wabigoon Subprovince and to the south by the Wawa Subprovince. In more recent subdivisions (e.g. Percival et al. 2006, 2012; Stott et al. 2010) of the Superior Province into “terranes” and “domains” the Quetico Subprovince is commonly referred to as the Quetico basin or Quetico terrane and it is bounded to the south by the Wawa-Abitibi terrane and to the north by the Western and Eastern Wabigoon terranes and the Marmion terrane. In this guidebook, we will refer to the “Quetico” as the Quetico Subprovince (QS) to avoid any interpretive tectonic implications. Similarly, rather than discussing subprovinces or terranes bounding the QS to the south, we will simply refer to the Shebandowan greenstone belt (SGB). The detailed geology of the QS (as a whole) is somewhat poorly understood. Systematic OGS mapping of large portions of the QS has not been carried out previously at 1:50 000 or 1:20 000 scale. Consequently, accurate bedrock geology maps of much of the QS do not exist, nor do large scale regional geochronology or geochemistry datasets that are tied to geological mapping. General regional geological syntheses of the QS are provided by Percival (1989) and Williams (1991). Additional synoptic descriptions of the QS are included in Percival et al. (2006, 2012) and these include a summary of existing geochronological constraints. Additional influential studies on the metamorphic history of the QS include Pan, Fleet and Heaman (1996); Valli et al. (2004) and a recent PhD study by Rehm (2025) among others. The QS has historically been interpreted to have been deposited in a fore-arc setting (e.g., Percival 1989, Williams 1991). In reality, the tectonic setting is likely more complex. Geochronology indicates most of the QS was deposited after circa 2700 Ma. However, - 44 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 1 (A) Total magnetic field image of the map area (Ontario Geological Survey 2017), underlain with lidar imagery (Ministry of Natural Resources and Forestry 2023). (B) Geological map (modified from Launay and Metsaranta, 2023) of the field trip area showing the location of stops presented in this guidebook. Note that Stops 13-15 are just to the north of the area portrayed by this map. Geological abbreviations: BLI, Barnum Lake intrusion; CCF, Crayfish Creek fault; CLI; HLG, Hilma Lake granite; HLI, Hadwen Lake intrusion; HLIC, Hades Lake intrusive complex; KF, Kingfisher fault; MFP, Moving Post fault PLIC, Penassen Lakes intrusive complex; QDZ, Quetico deformation zone; RLIC, Roll Lake intrusive complex; SFIC, Silver Falls intrusive complex; SIC, Shabaqua intrusive complex; TBLLF, Thunder Bay–Loon Lake fault. constraints vary by location (see discussion in Percival et al. 2006; and references therein) with some authors indicating deposition between approximately 2698 Ma and 2696 Ma and others indicating deposition after approximately 2692 Ma. Maximum depositional ages are poorly constrained because of the limited availability of representative and consistent detrital zircon datasets across the Quetico Subprovince, making stratigraphic and tectonic interpretations challenging. A framework for deformation and metamorphism summarized in - 45 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Percival et al. (2006 and references therein) suggests polyphase deformation and metamorphism spanned from close to the time of deposition to approximately 2650 Ma. Williams (1991) described four discrete deformation episodes affecting the QS. Although work on the metamorphic history of the Quetico differs regarding details, most work converges on the prevalence of subprovince-wide high temperature, low pressure metamorphism, which was likely preceded in some places by early medium-pressure and temperature metamorphism. Metamorphic grade increases in the eastern part of the QS where it reaches granulite-facies conditions (see Pan et al. 1998). Intrusive rocks are abundant in the QS, their characteristics are explored in the field guidebook and general characteristics are summarized by Williams (1991). Much attention has been paid to the boundary between the QS and the Wabigoon subprovince (e.g. the Beardmore-Geraldton greenstone belt), however, much less has been paid to the geology of the southern boundary. The SGB (and correlative greenstone belts in Minnesota) is a relatively narrow, arcuate greenstone belt, that extends from the Pass Lake area (east of Thunder Bay) to Northern Minnesota. The SGB is described in detail in Williams et al. (1991). A more recent geochronology based tectonostratigraphic framework for the SGB was proposed by Corfu and Stott (1998) and this remains in common usage as a stratigraphic and structural framework. Minor modifications to the Corfu and Stott (1998) framework have been added by Lodge (2016). In contrast to the QS, much of the SGB has been mapped by the OGS at 1:20 000 scale. However, much of this mapping was carried out prior to technological advancements like the widespread use of U-Pb geochronology, routine high precision trace element geochemistry, access to lidar imagery and high-resolution airborne magnetic data. That said, the OGS also has an on-going multiyear bedrock mapping project in progress to map much of the eastern part of the SGB at 1:20 000 scale (e.g., Lodge 2014; Ratcliffe 2016, 2017, 2019). The general greenstone belt-wide tectonostratigraphic framework for the SGB described by Corfu and Stott (1998) includes circa 2720 Ma aged rocks of the Greenwater assemblage (mainly tholeiitic mafic metavolcanic rocks and lesser ultramafic metavolcanic rocks, mafic-ultramafic intrusive rocks and metasedimentary rocks), circa 2718 Ma age rocks of the Burchell assemblage (mainly calc-alkalic felsic to intermediate metavolcanic rocks), circa 2695 Ma aged rocks of the Kashabowie assemblage (mainly calc-alkalic intermediate metavolcanic and metasedimentary rocks), circa 2690Ma aged rocks of the Shebandowan assemblage (calc-alkalic intermediate metavolcanic rocks, shallow marine and fluvial metasedimentary rocks) and younger than circa 2682 Ma aged rocks of the Auto Road assemblage (conglomerate). Corfu and Stott (1998) envisaged a structural history of D1 thrusting that interleaved the Greenwater assemblage along with the Burchell assemblage with the Kashabowie assemblage followed by a regional unconformity overlain by younger rocks of the Shebandowan and Auto Road assemblages deposited during D2 transpression. D2 transpression ceased by about 2680 Ma. According to the framework of Corfu and Stott (1998) intrusive rocks in the SGB include older gneissic tonalitic rocks to the south of the belt with ages as old as approximately 2750Ma, syn-Greenwater assemblage mafic-ultramafic intrusions, syn-Kashabowie assemblage tonalite, syn-Shebandowan assemblage monzodiorite-granite (Tower stock) and post-tectonic circa 2680 Ma aged intrusions of biotite-hornblende bearing diorite to granodiorite. Locally, evidence for magmatic rocks with ages around 2710 Ma are present in some parts of the SGB, e.g. Kabaigon porphyry (Corfu and Stott 1998). Geology of field trip area This fieldtrip will examine the geology of four distinct geological domains (see Figure 1): 1) the northeastern part of the Shebandowan greenstone belt, 2) the Lappe domain, 3) the southern Quetico domain and 4) the Dog Lake injection complex (Figure 1). Figure 2 is a geological timeline summarizing important events affecting the different geological units in the QS-SGB boundary zone and southern QS compiled from unpublished OGS data and various other sources. Synoptic reviews of these domains are given below. Additional details are provided in the field trip stop descriptions and will be augmented by discussions in the field. - 46 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 2 Geological timeline summarizing the main volcanic, sedimentary, intrusive, and structural events affecting the Shebandowan greenstone belt and the Quetico Subprovince. Ages are compiled from Corfu and Stott, 1998; Corfu, 2000; Kamo, 2013; Wang et al., 2020 and preliminary OGS data. Age bars include analytical uncertainties. Shebandowan greenstone belt (Stops 1, 2, 3, 5 and 6) This field trip guidebook only examines a narrow portion of the northern margin of the SGB that was covered by our mapping (Figure 1). In this area, the northern boundary of the SGB is generally eaststriking dextral shear zone interpreted to be the eastward extension of the Crayfish Creek fault. (Figure 1). Within this area of the SGB, we recognize four mappable units at the 1:50 000 scale which are subdivided into two informal groups, each comprising two informal formations. The older Greenwater group (a less repetitive Group-level name should be devised) consists of the Greenwater and Mud Lake formations and the younger Shebandowan group consists of the Strawberry Hill and Auto Road formations. Although not specifically identified in our area of mapping, we would include the “Kashabowie assemblage” (e.g. Corfu and Stott 1998) with the Shebandowan group. These units correspond with the “older” and “younger” portions of the SGB as described by previous workers (e.g., Corfu and Stott 1998, Lodge 2016) in most respects. However, we feel that moving towards a “sub-assemblage level” nomenclature is warranted to begin a framework for more detailed characterization of supracrustal rock variability at the regional scale. This is particularly true for rocks of the Shebandowan assemblage (in the sense defined by previous workers) which is lithologically heterogeneous. Greenwater group The Greenwater formation (Stops 1 and 6) consists mainly of tholeiitic mafic metavolcanic rocks, minor ultramafic metavolcanic rocks, synvolcanic gabbroic intrusions and minor clastic and chemical metasedimentary rocks. We do not have specific age constraints on the Greenwater formation; however, we infer that it is part of the “older” SGB based on lithological similarities with rocks of the Greenwater assemblage sensu stricto. At more detailed mapping scales, the Greenwater formation could likely be further subdivided (e.g. mafic dominated vs ultramafic dominated portions). The Mud Lake formation (Stop 1) consists mainly of calc-alkalic fragmental volcaniclastic rocks and locally coherent flows of felsic to intermediate composition. In the area, Corfu and Stott (1998) determined the age of this unit to be 2718 +/- 3 Ma. These are likely equivalent to Burchell assemblage of Lodge (2016). - 47 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Shebandowan Group The Strawberry Hill formation (SHF, Stop 2) typically consists of coarse-grained polymictic breccias characterized by hornblende phenocrysts in a dark matrix. The SHF is typically mafic to intermediate and calc-alkalic. It typically has elevated magnetic susceptibility and displays pink to red hematite alteration and/or pale green epidote alteration. Locally, it also occurs as more massive, hornblende-phyric mafic flows or shallow intrusions. At some localities, breccias or flows are associated with thinly layered tuffs, and reworked tuffs with clear pyroclastic textures such as bombs that deform layering. Geochronology by Corfu and Stott (1998) and our own work indicate deposition/eruption of the SHF at circa 2690 Ma. Although the bulk of SHF rocks are undeformed, they are locally cut by narrow ductile shear zones, and it is in sheared contact with older rocks. The SHF forms a thin, but important marker unit that can be correlated across much of the central SGB in the area depicted by Figure 1. Breccias of the SHF are compositionally similar to, and of the same age as the Tower stock (just west of the area depicted in Figure 1) which hosts low-grade disseminated, intrusion related gold mineralization and includes marginal breccias similar to the SHF (e.g. Carter 1992). The Auto Road formation (ARF, Stops 3 and 5) comprises mainly polymictic, matrix supported conglomerate. Local occurrences of trough crossstratified, likely fluvial sandstones, are also considered part of the ARF. Calc-alkalic mafic metavolcanic rocks, including apparently pillowed flows are locally intercalated with ARF sedimentary rocks. The ARF was deposited after 2682 ± 3 Ma based on geochronology in Corfu and Stott (1998) and as such, it clearly postdates the SHF. Dextral shear zones are a common feature of the SGB. Although it is not clear in Figure 1, geophysical patterns in adjacent areas like the LD and the SGB outside of our mapping area suggest that D2 shear zones post date D1 thrust faults. Sinistral northeast-trending shear zones in the SGB such as the Kingfisher and Thunder Bay-Loon Lake faults are relatively younger than the dextral shear zones based on mapping inferred off-sets. Potassium-rich calc-alkalic suite intrusions (PRCAS) form a minor component of the SGB as shown on Figure 1. These include massive to weakly foliated hornblende-biotite-magnetite quartz monzonite to monzogranite dominated intrusions of unknown age. These may be related to similar intrusions in the SGB like the Kekekaub pluton (circa 2680 Ma) or perhaps correlate with the Tower stock (circa 2690Ma). Lappe Domain (Stops 4, 7 and 9) The Lappe domain comprises mainly metasedimentary rocks (wacke and siltstone) similar to those of the southern Quetico subprovince to the north. Its southern boundary is the Crayfish creek fault whereas it is bounded to the north by the Moving Post fault. The LD is characterized by thin fault bounded panels of mafic metavolcanic and mafic intrusive rocks comparable to the Greenwater formation intercalated with the metasedimentary rocks. Where best preserved, these mafic panels contain pillowed mafic flows, local banded iron formations, local thin ultramafic schists (sheared flows or thin sills) and local sulfidic mudstones. The margins of the mafic panels are commonly sheared and often preserve well developed steeply plunging stretching lineations indicating dip-slip, probable thrust motion. Locally LD rocks are folded, however we do not have a sufficient coverage of detailed younging data or outcrop scale fold observations to determine the nature of folding in the LD. Although we do not have direct age constraints on metavolcanic rocks in the mafic panels, preliminary data suggests some thin gabbro bodies in LD metasedimentary rocks are intrusive (i.e. not structurally interleaved). These provide minimum age constraints for LD sedimentation; combined with preliminary detrital zircon data, and considering analytical uncertainties, LD sedimentation is bracketed between about 2698 and 2689 Ma. At another locality, Corfu (2000) determined and age of circa 2718 Ma for a gabbro within one of the mafic panels in Ware township. If this age is reliable, then some of the mafic rocks in the LD correlate with the Greenwater formation. Another hypothesis to consider is that this age could reflect zircon inheritance. Regardless of the age of the mafic panels and whether they represent tectonic slivers of older rocks, or if they are part of the “stratigraphy”, observed thrusts faults indicate that the boundary between the SGB and the QS likely represents a zone of fold-thrust deformation. The timing of LD sedimentation corresponds with the timing of deposition of the Kashabowie assemblage in the SGB (see Corfu and Stott 1998). Observed thrust - 48 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 faults in the LD may therefore correspond to “D1” of Corfu and Stott (1998) and this interpretation links the timing of early QS deformation with early deformation in the SGB. East of the Kingfisher fault, large, multiphase, PRCAS intrusive complexes, (the Penassen Lakes intrusive complex and the Roll Lake intrusive complex) were emplaced into the LD. These intrusions consist of an early mafic phase (hornblendite to monzogabbro) roughly coeval with intermediate a hornblende-biotitemagnetite monzodiorite to quartz monzonite phase and a late phase that is volumetrically dominant and composed of biotite monzogranite. Compositionally similar rocks are found to the north in the QS and the Dog Lake injection complex and ages determined for the different phases are consistent regionally as summarized in Figure 2. Locally, peraluminous granitic pegmatites occur in the northern LD (e.g. Walkinshaw pegmatites) but are not associated with any obvious parental granite. LD metasedimentary rocks are typically low metamorphic grade, dominated by biotite or chlorite, quartz, plagioclase assemblages. However, near intrusions they locally contain contact metamorphic porphyroblasts of andalusite and/or cordierite and in some areas experienced partial melting. Southern Quetico domain (Stops 10, 11 and 12) The southern Quetico domain comprises mainly metasedimentary rocks (wacke and minor siltstone) with rare intermediate tuffaceous horizons, rare mafic tuff (possibly boninitic). Bedding and foliations in the southern QS are typically east to northeast trending and “D2” folds typically have east to northeast trending axial surfaces. Southern QS metasedimentary rocks gradually become more recrystallized towards the north. Metamorphic assemblages are typically dominated by biotite and locally biotite-garnet. Andalusite- and cordierite-bearing metamorphic assemblages are also relatively common and may related to proximity to intrusions. Staurolite-bearing assemblages are present locally but rare. The southern QS was intruded by numerous potassium-rich calc-alkalic suite intrusions (PRCAS). These are depicted on Figure 1 and include from west to east, the Shabaqua intrusive complex, the Silver Falls intrusive complex, the Trout Lake intrusion, the Barnum Lake intrusion, the Whitelily Lake intrusive complex and the Hades Lake intrusive complex. These intrusions and intrusive complexes are variably complex mixtures of mafic (hornblendite-monzogabbro), intermediate (monzodiorite-quartz monzonite) and felsic (monzogranite) phases. S-type granites are also common in the southern QS, these include the Hilma Lake granite, the Voutilainen intrusion and the Hadwen Lake intrusion. Peraluminous granitic pegmatites are also abundant and spatially related to S-type granite bodies. Dog Lake injection complex and Quetico deformation zone (Stops 12, 13, 14 and 15) Strain and degree of metasedimentary rock recrystallization increase abruptly in the vicinity of the Quetico deformation zone (QDZ) in the northern part of the area. In this domain, QS metasedimentary rocks are recrystallized and comprised mainly of biotite-quartzfeldspar+/- magnetite paragneiss and locally also sillimanite-cordierite-garnet bearing paragneiss. The Dog Lake injection complex (DLIC) is characterized by paragneiss intruded by a high volume of both peraluminous and HPCAS intrusions (injections) that were emplaced synchronously with intense dextral transpression along the QDZ. Intrusions of both suites are commonly schlieric with strong fabrics defined by schlieren and magmatic minerals. At the contact with HPCAS intrusions, paragneisses are commonly strongly magnetic which likely resulted from their oxidation by fluids exsolved from these HPCAS intrusion triggering the crystallisation of magnetite. These zones are also particularly rich in biotite which locally give the paragneisses the appearance of melanosome. Migmatitic rocks are a volumetrically minor component of the DLIC and comprise mainly patchy metatexite likely related to heating by the high volume of intrusive rocks in the area. Syn-tectonic fabrics are ubiquitous in intrusive rocks of the DLIC. Strong fabrics are generally steep and east striking to east-northeast striking. Dextral shear bands with strikes of approximately N290-300 are common as are approximately N40 striking and N15-20 striking subvertical sinistral shear bands. C-S fabrics are common and suggest syn-emplacement dextral strike slip and locally north side up thrust components of motion. Shearing related fabrics in the paragneisses have the same orientations and kinematics and syn-tectonic emplacement fabrics in the granitoid rocks. Folding of gneissosity is common and folding - 49 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 tends to be gently plunging. Intense, steeply dipping, east striking mylonitic zones are present locally. Late brittle-ductile strike slip and thrust motion occurred along the QDZ locally overprinting ductile fabrics. This pattern is repeated at map scale where the sinistral north to northeast-trending shear zones branches onto dextral east-trending QDZ in the Dog Lake area (see Figure 1). These observations suggest a transition from an earlier ductile transpressive deformation to later more brittle-ductile deformation. Field trip stop descriptions Stop 1 (Optional) - Mafic metavolcanic rocks of the Greenwater formation and felsic to intermediate metavolcanic rocks of the Mud Lake formation 315073E 5376695N (Greenwater formation) 314610E 5377220N (Mud Lake formation) Park on the shoulder of Mud Lake Road. Wear reflective vests, stay on shoulder or in the ditch. Traffic is heavy on Hwy 102 so be very cautious crossing the highway. A series of outcrops in this area shows mafic metavolcanic rocks considered to be part of the Greenwater formation and felsic metavolcanic rocks of the Mud Lake formation. These two formations are typical of the older part of the Shebandowan greenstone belt. From the junction of Hwy 102 and Mud Lake Road, outcrops immediately to the east and west are mainly mafic metavolcanic rocks of the Greenwater formation. These rocks display well preserved volcanic features such as prominent pillows (Figure 3A) and local pillow breccias. The pillowed flows are subvertical and striking to N75. Based on pillow cusps, they appear to young northward. Quartzepidote veining, local red-pinkish alteration and east striking brittle-ductile shear zones can also be seen at this outcrop. Younger, mica-phyric mafic lamprophyre dikes are also present. Farther west, closer to the north end of Mokomon Lake (314610E, 5377220N) felsic metavolcanic rocks of the Mud Lake formation comprising tuff breccias, lapilli tuffs and locally flows are present in outcrops located on the north side of the highway. These felsic metavolcanic rocks host a thin, semi-massive sulfide (sphalerite, pyrite, pyrrhotite) horizon known as the Mud Lake VMS occurrence (Figure 3B). The rocks Figure 3. Metavolcanic rocks of the Greenwater and Mud Lake formations. A) Large pillows in mafic flow, Greenwater formation. B) Sulfide mineralization in felsic metavolcanic rocks, Mud Lake formation. here are strongly foliated (260/75) with local shearing (234/80) and locally cut by rusty shallow dipping faults. Felsic rocks from this outcrop have an age of 2718 +/- 3 Ma based on Corfu and Stott (1998). The age of Greenwater formation (Greenwater assemblage) rocks throughout the greenstone belt is mainly inferred from adjacent felsic to intermediate units and maficultramafic intrusions. Although the contact between these two units appears sharp at this location, mafic rocks of the Greenwater formation are intercalated with felsic to intermediate rocks of the Mud Lake formation in other locations, suggesting that the contact may have originally been gradational. - 50 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Stop 2 (planned) - Strawberry Hill formation, Shebandowan group 312462E 5378109N Park along the access road to the quarry on the southern side of Dawson Road. Participants must always wear reflective vests and remain on the road shoulder, as traffic along this section is relatively dense and driver visibility is poor. This stop exposes a representative outcrop of the Strawberry Hill formation of the Shebandowan group. It consists of a massive, undeformed, mafic to intermediate calcalkaline, hornblende-phyric, matrix-supported breccia (Figure 4A). The breccia is polymictic, containing angular to subrounded clasts composed predominantly of plagioclase-phyric, medium- to coarse-grained pink monzonite, along with subordinate clasts of mafic and intermediate volcanic rocks, all set within a fine-grained, dark-green matrix. Clasts of monzonitic composition locally preserve an internal magmatic foliation, highlighted by the alignment of plagioclase phenocrysts. This magmatic fabric suggests that the intrusion from which the clasts were derived was likely emplaced syn-tectonically. The absence of visible bedding, combined with the generally angular to sub-rounded nature of the clasts, suggests formation in a high-energy volcanic environment, possibly associated with a cryptodome, and likely proximal to the volcanic source. Alternatively, this unit may represent a subvolcanic magmatic breccia, comparable to the breccias around the Tower stock described by Carter (1992). Based on TIMS U–Pb ages reported by Corfu and Stott (1998), magmatism related to this breccia likely occurred at approximately 2692±6 Ma. Thus, the SHF is likely contemporaneous with the 2690 ± 3 Ma Tower stock (Corfu and Stott 1998) Although the unit is largely massive and lacks visible foliation, discrete mylonitic shear bands are locally present (Figure 4B). These shear bands are commonly associated with carbonate alteration and quartz–carbonate veining. The shear zones generally strike northeast and locally preserve kinematic indicators consistent with a thrust motion, indicating a northsideup sense of shearing (Figure 4B). The breccia is also cut by multiple generations of quartz–carbonate veins, indicating postdepositional brittle deformation coeval with hydrothermal activity. These veins locally offset both clasts and matrix but do not significantly disrupt the overall massive character of the breccia. Stop 3 (Planned) - Auto Road formation, Shebandowan group 316851E 5378641N Park at the entrance of the private dirt road south of Korpela Road. As Korpela Road is narrow, please ensure that your vehicle does not obstruct traffic or restrict access along the road. Figure 4 Representative photographs of the Strawberry Hill formation outcrop (Stop 2). (A) Massive poorly sorted matrix supported polymictic intermediate breccia. (B) Discrete mylonitic shear band with asymmetric kinematic indicators (C-S fabric) indicating a north-side-up sense of shearing. This stop exposes a representative outcrop of the Auto Road formation of the Shebandowan group. It consists of a strongly foliated, poorly sorted, matrixsupported polymictic conglomerate. The conglomerate contains predominantly pebble to boulder-sized clasts of plagioclasephyric, medium to coarse-grained pink monzonite and monzogranite, many of which are - 51 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Road formation deformation event to approximately 2688 ± 0.8 Ma, whereas TIMS U–Pb ages reported by Corfu and Stott (1998) indicate a maximum depositional age of 2682 ± 2 Ma for the conglomerate. Together, these ages suggest that the intrusions from which the clasts were derived were deformed after 2688 Ma, prior to erosion and deposition of the conglomerate sometime after 2682 Ma. The conglomerate was subsequently deformed and affected by dextral shearing likely related to the Crayfish Creek fault. Stop 4a (Planned) - Sheared mafic rocks, mediumbedded wackes and thrust deformation at the Northern boundary of Lappe domain. 326238E/ 5383267N Park along Moving Post Road or in the parking lot of the old Lappe Store if permission is obtained. Wear reflective vests, be mindful of traffic, shoulders of the road are narrow and visibility is poor. Figure 5 Representative photographs of the Auto Road formation outcrop (Stop 3). (A) Strongly foliated polymictic conglomerate. (B) Dextral asymmetrical C-S fabric wrapping around a clast of pink monzogranite. Note the discordant internal foliation within the clast. strongly flattened parallel to the foliation (Figure 5A). The matrix is sandy, medium to coarse-grained, and characterized by a darkgreen color. Several monzonitic and monzogranitic clasts preserve an internal foliation that is discordant with the matrix foliation (Figure 5B), indicating that these intrusive rocks were deformed prior to erosion and deposition. This relationship suggests a preAuto Road formation deformation event affecting the source intrusions. The conglomerate exhibits a strong east–west trending foliation and is overprinted by a northwesttrending (approximately N300°) dextral shearing, highlighted by the development of asymmetric C–S fabrics wrapping around the clasts (Figure 5B). Preliminary ages obtained from a foliated intrusive clast constrain the maximum age of the preAuto This outcrop illustrates strongly deformed, tholeiitic mafic metavolcanic rocks (Figure 6A) of the northernmost mafic metavolcanic unit of the Lappe domain. Mafic metavolcanic rocks at this exposure are characterized by N250 striking north-dipping strong foliation and well-developed northward plunging lineation. The apparent dip-slip motion along the shear zone is north-side-down. In its present geometry, the true kinematics of the dip-slip motion along this structure is equivocal (Figure 6B). However, an interesting and commonly repeating pattern along strike is that metamorphosed north dipping wackes located north and south of this mafic metavolcanic unit consistently young southward indicating that the whole stratigraphic succession is overturned. This pattern was also observed in the past OGS mapping campaign of MacDonald (1939, observe printed version of old map). If our interpretation of the kinematics of this structure and the facing direction in the bounding metagreywacke units are correct, a possible interpretation of this structure is that it represents an originally northward verging thrust that was subsequently steepened and overturned. The stratigraphic relationship between the mafic metavolcanic rocks at this locality and surrounding wackes is not well constrained. Commonly both contacts of the mafic unit are sheared and there is a paucity of rocks suitable for geochronology in the exposures that we have mapped. Reliable younging - 52 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Stop 4b (Optional) - Southward younging Lappe domain metasedimentary rocks 326207E 5382509N This optional outcrop is located approximately 750 m south of Stop 4a along Dog Lake Road. It exposes mediumbedded wackes displaying a southward younging direction, as indicated by graded bedding and load casts (Figure 7A and 7B). The southward younging of these clastic metasedimentary rocks occurs near the mafic metavolcanic rocks and associated thrust fault observed at Stop 4a, providing important constraints on local stratigraphic facing and structural relationships. Figure 6 Representative photographs of sheared mafic volcanic flow from the Lappe Domain (Stop 4). (A) Strongly foliated and sheared mafic volcanic flow. (B) C-S fabric wrapping around quartz eyes indicating north-side down sense of shearing indicators within the mafic metavolcanic unit are almost nonexistent. At one locality, farher to the east, southward younging pillows were observed along a similar structure in a similar setting. We have not observed strong evidence of stratigraphic continuity between the surrounding wackes and the mafic unit. In this case, observed younging directions do not argue against stratigraphic continuity, however the sheared nature of contacts makes interpretation difficult. A thin, mica-phyric lamprophyre dike is also present at this locality. Mafic lamprophyre dikes are common throughout the area in the SGB, LD and QS. They have not been successfully dated and their contact relationships and relationships to structures and other intrusive suites is difficult to interpret as in many places relative age relationships are contradictory. This may Figure 7 Clastic sedimentary rocks of the Lappe Domain indicate multiple generations of lamprophyric mafic (Stop 4b). (A) Medium bedded wackes with graded beds. (B) intrusion are present regionally. Flame structure showing a southward younging direction. - 53 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Stop 5 (Optional) - Cross bedded sandstone, Auto Road formation, Shebandowan group 329269E 5379186N Park along the south side of Peterson Road, near the entrance to the private residential access road located on the curve. This outcrop is situated on private property. Authorization from the landowner is required prior to accessing the outcrop, and participants must ensure that permission has been obtained before entering on the property. This large outcrop exposes a well-preserved section of sandstone in sheared contact with a calc-alkaline mafic volcanic flow (Figure 8A). The sandstone displays a variety of well-developed sedimentary structures, including crossbedding and channelized geometries, indicative of a fluvial depositional environment (Figure 8B). The sandstone locally contains plagioclase phenocrysts, suggesting a potential juvenile volcaniclastic component. The mafic lava flow is locally pillowed and occurs in sheared contact with the sandstone (Figure 8C). The shear zone is characterized by a penetrative east– west-striking foliation that dips steeply to the south. A well-developed stretching lineation, plunging steeply (~55°) to the east, is observed on foliation planes. Locally, kinematic indicators are preserved and indicate a dextral sense of shearing. Together with the steeply plunging lineation, these observations suggest a dextral transpressional deformation with a top-to-the northwest thrust component. Younging directions determined from cross bedding indicate a consistent southward younging across the outcrop. The sandstone is also crosscut by late, narrow mafic dikes, indicating post-depositional magmatic activity (Figure 8D). Although samples collected for U–Pb geochronology Figure 8 Outcrop of cross-bedded sandstone of the Auto Road formation (Stop 5). (A) Aerial drone photograph showing crossbedding and channel structures. (B) Close up on cross-stratified sandstone with southward younging direction. (C) Strongly sheared and foliated mafic volcanic flow occurring within the sandstone. (D) Late mafic dikes crosscutting sandstone. - 54 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 did not yield datable mineral phases, the sandstone is interpreted to be part of the Shebandowan group, most likely the Auto Road formation, based on its characteristic fluvial depositional environment. Stop 6 (Planned) - Greenwater assemblage mafic metavolcanic rocks, eastern extension of Crayfish Creek deformation zone 340868E 5376210N Park on the shoulder of Mount Baldy Road at its junction with Hwy 527. Wear high visibility vests. The shoulder here is narrow and logging truck traffic can be heavy. Be careful if crossing the highway. Footing is uneven and there are commonly garbage and glass in the ditches. This outcrop represents the sheared contact between the Shebandowan greenstone belt (to the south) and the Lappe domain (to the north) and may represent the eastward extension of the Crayfish Creek deformation zone. The northern part of the outcrop consists mainly of east-striking, steeply south-dipping, sheared, ankerite altered, magnesium-rich mafic rocks (Figure 9A). During mapping, kinematics of the shearing at this locality were not determined confidently. Precise identification of protoliths in the northern part of the outcrop is problematic as most primary features were obliterated. However, towards the south, rock types are well preserved and include massive, fine- to mediumgrained mafic volcanic flows (Figure 9B), mafic pillowed flows, a thin pyrite-bearing nodule black mudstone, and quartz-feldspar porphyritic intermediate dikes. Enigmatic weakly boudinaged dikes of mafic to ultramafic composition locally cut the main shearing fabric in the northern part of the outcrop. Minor Proterozoic calcite veins are also present. Lappe domain metasedimentary rocks to the north were deposited after circa 2700 Ma and perhaps after circa 2690 Ma, depending on the interpretation of preliminary detrital zircon data. Based on geochronology performed elsewhere in the SGB, the Greenwater formation is inferred here to have an age of circa 2720 Ma. Therefore, this shear zone juxtaposes rocks that differ in age by at least 20 million years. At this locality, shearing could represent a transpressive dextral reactivation of an earlier shear zone that interleaved units of disparate age. Note that there does not appear to be a rhyolitic unit equivalent to the Mud Lake formation north of the Greenwater formation as seen in Stop 1. This feature could be attributable to either a fault-related subtraction or a lateral stratigraphic discontinuity. The “QFP” dikes cutting the Greenwater formation here have the same appearance as dikes commonly observed in the Lappe domain and in the southern Quetico. Unfortunately, these dikes have proven difficult to date due to the lack of mineral phases amenable to U-Pb geochronology. Pyritic black shales like those at this locality occur locally in the Greenwater and Mud Lake formations. Figure 9. Greenwater formation metavolcanic rocks (Stop 6). (A) ankerite altered mafic-ultrmafic schist. (B) Massive, plagioclase-phyric mafic flow. - 55 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Stop 7 (Optional) - Lappe domain metasedimentary rocks 341256E 5378262N Park at the “weigh-scale” on the west side of Highway 527. Wear high visibility vests and use a high level of caution crossing the highway to the outcrop. Ditches also have uneven footing and garbage. This outcrop illustrates low metamorphic grade rocks of the southern Lappe domain. Here ~ 250° striking, north dipping but southward younging metasedimentary rocks include thin- to mediumbedded intercalated siltstone and sandstone (Figure 10A) overlain by very thickly bedded poorly sorted volcaniclastic sandstone (Figure 10B). Near the base of the thick sandstone bed, there is a folded horizon of thinly interbedded sandstone and siltstone. This may represent syn-depositional soft deformation. Locally, sparse carbonate nodules are present in the outcrop; these have been interpreted as early diagenetic features. Farther north, calc-silicate nodules (amphibole, epidote, locally garnet) are common in the QS and probably represent more metamorphosed equivalents of these carbonate nodules. As alluded to in the description of Stop 6, Laserablation-ICP-MS zircon geochronology was carried out on samples from this outcrop. This data suggest deposition of these rocks about the same time as much of the Shebandowan group. However, analytical precision does not permit precise chronostratigraphic correlation with the Strawberry Hill or Auto Road formations. Maximum depositional ages for tidally influenced shallow marine sediments in the Finmark area have maximum depositional ages of about 2691 Ma based on limited population, single crystal IDTIMS geochronology reported by Corfu and Stott (1998). The Finmark metasedimentary rocks occur in a similar structural setting based on geophysical interpretation. Stop 8 (Optional) - Northern margin of the Penassen Lakes intrusive complex 345318E 5385843N This stop requires parking on the shoulder of Hwy 527. Use hazard lights and traffic cones to increase visibility. Wear reflective vests and be mindful again of the traffic on Hwy 527. Be also mindful of soft shoulders when parking and walking. This outcrop represents part of the northern contact of the Penassen Lakes intrusive complex. At this outcrop early hornblende monzodiorite is crosscut by intermediate aged hornblende quartz monzonite, which is cut by late pink leucocratic biotite monzogranite dikes (Figure 11A and 11B). Also visible are narrow mica-phyric mafic lamprophyre dikes and xenoliths of metawacke and possibly mafic metavolcanic rocks. Figure 10. Lappe domain metasedimentary rocks at Stop 7. (A) steeply dipping, southward younging, thin- to mediumbedded, low metamorphic grade siltstone and sandstone. (B) Poorly sorted, lapilli and intraformational-sedimentary-clast bearing thick-bedded volcaniclastic sandstone. Multiphase, oxidized (magnetite bearing) intrusive complexes are a common feature of the SGB, LD and QS (see Figures 1 and 2). Early mafic phases of these intrusive complexes were emplaced between about 2677 and 2670 Ma, whereas later pink monzogranite phases appear to be about 5 million years younger (Figure 2). Although relative and absolute age differences between different phases of these intrusions are observed, we refer to them collectively as the potassium-rich calcalkalic suite. - 56 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Stop 9 (Planned) - Lappe Domain metasedimentary rocks and Walkinshaw peraluminous granitic pegmatites 346697E 5388265N Turn to the east on side road located just south of Stop 9 coordinate (Seagris Rd; no sign). If this side road is too rough for vehicles, use the road leading to summer camps on the northern end of Walkinshaw Lake, farther north. Wear high visibility vests, stay on shoulder or in ditch. Use extreme caution when crossing the road. Outcrops are relatively tall at this locality, be mindful of the potential for falling rocks in places. Figure 11. Northern margin of the Penassen Lakes intrusive complex at Stop 8. (A) Metasedimentary country rock fragments intruded by grey monzodiorite, crosscut by pink quartz monzonite to monzogranite dikes. (B) Amphibolephyric quartz monzonite with xenoliths of metamorphosed wacke. We consider this area part of the Lappe domain as we are south of the northernmost mapped mafic metavolcanic panel and the inferred eastward extension of the Moving Post fault. The Penassen Lakes intrusive complex and the similar Roll Lake intrusive complex to the north appear to post date the Moving Post fault based on geophysical interpretation and the presence of amphibolitic mafic pillowed flows occurring as large, strongly deformed inliers within the RLC and the emergence of a thin shear zone bounded mafic panel on the east side of the RLIC (Figure 1). This provides a clear relative age constraint on the Moving Post fault. These rocks are not, however, post-tectonic as we will see in later stops. This long outcrop contains relatively undeformed metasedimentary rocks (Figure 12A and 12B) in the northern part of the Lappe domain along with peraluminous granitic pegmatite dikes locally containing green mica, black tourmaline (Figure 12C and 12D) and disseminated molybdenite. These pegmatites we refer to as the Walkinshaw pegmatites. This area of metasedimentary rocks is surrounded by several large intrusive complexes (Potasssium-rich calc-alkalic suite), the Whitelilly Lake, Roll Lake and Penassen intrusive complexes, as well as several minor, sub-concordant, pink monzogranite bodies that are too small to map at 1:50 000 scale. At this locality sedimentary features are well preserved (see Figure 12A) and the overall strain appears low. Foliation-bedding orientation relationships and measured intersection lineations suggest that folds in this area likely plunge steeply. Locally, thin shear zones have steep lineation plunges. Finer-grained beds locally have well developed porphyroblasts of andalusite (Figure 12B) and some cordierite, both are commonly replaced by muscovite. These assemblages are consistent with high temperature-low pressure metamorphism. At this locality we interpret that the observed metamorphic assemblage results from proximity to the many large intrusions in the area. The Walkinshaw pegmatites are somewhat enigmatic. They occur in relatively low metamorphic grade rocks and there is no clear peraluminous “parent” granite nearby. A speculative explanation could be that small volume melts were locally produced by partially melting adjacent to contacts of nearby intrusions (PRCAS). There is local evidence for such melts, but only in very small volumes. - 57 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 12. Lappe domain metasedimentary rocks and the “Walkinshaw” peraluminous granitic pegmatites (Stop 9). (A) northward younging wacke bed based on scouring and normal grading. (B) Andalusite porphyroblast-rich bed. (C) and (D) Black-tourmaline-rich subconcordant muscovite pegmatite dike. Stop 10 (Planned) - Onion Lake pegmatites and folded Quetico metawacke 346817E 5398027N Turn east on Cliff Rd (no sign) and drive about 250m down the dirt logging road and park to one side. Be aware of potential for logging traffic or other road users. Wood ticks are common at this site in spring and early summer. Use caution while walking around on the uneven ground. This outcrop shows a clean exposure of a peraluminous granitic pegmatite typical of pegmatites we refer to as the Onion Lake pegmatites. At this stop, a biotite-muscovite-garnet bearing pegmatite-aplite dike (Figure 13A and 13B) strikes roughly northeast and appears to post-date a strong foliation affecting typical Quetico Subprovince metasedimentary rocks. The pegmatite displays prominent interlayering of pegmatitic and aplitic rock and unidirectional solidification textures (Figure 13A). This pegmatite is not far south of the contact of a peraluminous granite we refer to as the Voutilainen intrusion. Several large “whalebacks” of pegmatite are present in this area. Although not entirely clear at this locality, the Onion Lake pegmatites are boudinaged and commonly have internal fabrics defined by magmatic phases implying a syn-tectonic emplacement. Regionally, the northeastward strike of pegmatite contacts is parallel to sinistral shear zones which are interpreted to be antithetic structures related to the overall dextral shearing related to the Quetico deformation zone. Granites in this area occur near the southern margin of prominent deformation related to the QDZ. At least two distinct generations of peraluminous granitic pegmatites are present in the southern Quetico. A second generation of pegmatites, younger than the one at this locality crosscut at a high angle the foliation related to the Quetico deformation zone and therefore are post-tectonic. These later pegmatites are much less abundant, and we will not be able to examine the younger generation of pegmatites on this trip. Metasedimentary rocks at this locality are strongly deformed. Relatively steeply plunging, east-northeast striking z- to m-folding is revealed by prominent quartz-feldspar veins (Figure 13C). These quartzfeldspar veins are very common in the southern QS. - 58 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 13. Onion Lake peraluminous granitic pegmatite and folded Quetico metasedimentary rocks (Stop 10). (A) Pegmatite-aplite layering, unidirectional solidification textures, biotite-muscovite pegmatite and garnet aplite (B) Close-up of abundant garnet in aplitic phase, (C) boudinaged S-type granite dike sub-parallel to axial plane of “D2” folds in Quetico metawacke. Based on cross-cutting relationships they appear to predate most of the mapped intrusive suites. Note the narrow, boudinaged peraluminous granitic dike emplaced sub parallel to the axial plane of the folds appearing to crosscut the veining (Figure 13C). Outcrop scale folds of sedimentary layering are relatively uncommon in the southern Quetico making overall understanding of fold-geometries somewhat difficult. These folds are likely “D2” in the nomenclature of Williams (1991) and limbs of similarly oriented folds are elsewhere postdated by dextral shearing (D3). A prominent linear magnetic anomaly, caused by a relatively magnetic wacke unit, shows a clear regional z-folding pattern and this is likely the general geometry of “D2” folding in the southern QS. In this area, many traverses across-strike documented well preserved younging indicators that show multiple reversals over relatively short distances. These reversals likely represent parasitic folds in hinge zones of larger z-fold enveloping surfaces. Towards the north, in the Quetico deformation zone, fold orientations change and tend to be east-striking, upright or slightly inclined with gentle plunges. These folds have been interpreted as being part of the D3 event. Stop 11 (Optional) - Mylonite and late brittle-ductile deformation Quetico deformation zone 348059E 5401951N Pull vehicles over near the north end of long outcrop and park on the shoulder of Hwy 527. Keep the duration of stop relatively short. If longer stop required park on logging road just to the south. Wear reflective vests, use hazard lights. Traffic can be heavy. At this locality, highly deformed metasedimentary rocks and sheared and boudinaged muscovite pegmatites are present. Locally, north dipping brittle structures offset pegmatite dike contacts with a north over south sense of displacement (Figure 14A). Pale - 59 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 QS domain to the south and the Dog Lake injection complex to the north. Grey amphibole-biotite-magnetite quartz monzonite at this outcrop is crosscut by later pink, moderately magnetic biotite monzogranite (Figure 15A and 15B). The quartz monzonite is moderately foliated and syn-tectonic. The quartz monzonite and the biotite monzogranite are compositionally similar to bigger, typically less strained intrusions located farther south e. Conversely, these types of intrusions are highly strained to the north in the Dog Lake injection complex. Preliminary geochronology suggests that despite highly variable degrees of strain, PRCAS intrusions have comparable ages in the Lappe domain, southern Quetico Subprovince and in the Dog Lake injection complex. Weakly deformed intrusions like the Trout Lake and Barnum Lake intrusions are essentially contemporaneous with highly sheared syn-tectonic equivalents in the DLIC. Figure 14. Sheared Quetico metasedimentary rocks and peraluminous granitic pegmatites, Quetico deformation zone (Stop 11). (A) brittle minor off-set thrust fault post-dates dextral shearing related to the ductile phase of the QDZ. (B) Pale green, siliceous mylonite related to the Quetico deformation zone. green siliceous rocks exposed at the north end of the outcrop are likely a mylonitic band (Figure 14B) within the larger Quetico deformation zone. To the south, dark grey rocks are strongly deformed wacke. Stop 12 (Planned) - Intermediate and felsic phases of potassium-rich calc-alkalic intrusive suite and syn-tectonic schlieric S-type granite 348541E 5403237N Pull over on the shoulder of Hwy 527. Use hazard lights, wear reflective vests, use extreme caution when crossing the highway. This large outcrop illustrates contact relationships between intermediate and felsic phases of the potassium-rich calc-alkalic intrusive suite (PRCAS) and a schlieric biotite-rich peraluminous granite. This outcrop represents the transition from the southern At the north end of the outcrop, syn-tectonic, schlieric, low magnetic susceptibility peraluminous leucogranites are in contact with rocks of the PRCAS intrusions. C-S fabrics in the granite, and narrow sheared bands (Figure 15C and 15D) indicate north side up thrusting with a dextral strike-slip horizontal component during emplacement. East-northeast striking foliations locally bear shallowly plunging stretching and mineral lineations indicating strike slip motion. These lineations may have formed under brittleductile conditions after the main phase of ductile syngranite shearing. The relative age of the peraluminous intrusion and the intermediate PRCAS phase is not immediately clear at this exposure. Regionally, the intermediate phase of the PRCAS slightly predates the bulk of S-type granite intrusions, and pink biotite monzogranites are typically younger. In some areas, hybridization of magmas have been documented. Stop 13 (Planned) - Shear-hosted leucogranitic injections, Dog Lake injection complex 346928E/ 5407112N (this stop is not on Figure 1) From Highway 527, turn right onto Hiccup Road (a logging road). Park on the curve near the stack of logs. This road is not active at the time of writing, and traffic is expected to be minimal. This outcrop exposes paragneiss of the Dog Lake complex intruded and variably digested by large volumes of syntectonic leucogranitic injections (Figure - 60 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 15. Potassium rich calc-alkalic suite intrusions and schlieric peraluminous granite at Stop 12. (A) Grey, foliated, feldspar porphyritic, hornblende-biotite quartz monzonite cross but by dikes of pink biotite monzogranite; (B) Porphyritic texture in quartz monzonite. (C) and D) syn-emplacement C-S fabrics defined by biotitic schlieren in biotite-rich peraluminous granite indicate a north-side up thrust component of motion (C) and dextral strike slip component of motion (D) during peraluminous granite emplacement. 16A), producing raft and schollen textures that can be easily confused with diatexite, and may therefore lead to misleading interpretations. The outcrop displays variable degrees of assimilation and digestion of the sedimentary host rocks by granitic melts, locally producing biotite schlieren within the leucogranite. Leucogranite injections are heterogeneous, ranging from coarse-grained to porphyritic textures (Figure 16B). They occur as sheeted to irregular intrusions that clearly exploit east-west trending foliation planes and northwest-trending dextral shear bands within the paragneiss host rock. This strong structural control indicates syntectonic emplacement facilitated by regional dextral zones related to the Quetico deformation zone. Locally, antithetic sinistral shear bands are also observed. Wider and more homogeneous granite injections locally contain garnet and pegmatitic segregations (Figure 16C and 16D). The presence of these pegmatitic segregations indicate a high degree of melt fractionation, which is incompatible with in situ partial melting. This interpretation is supported by chondritenormalized REE patterns, which display a strongly fractionated geochemical signature and variably developed negative Eu anomalies (Figure 17), comparable to those observed in the S-type granite intrusions of the Quetico subprovince. These features indicate that granitic melts had already undergone significant plagioclase fractionation at depth forming cumulates before extraction of the residual melt along shear zones. Although some textures locally resemble those seen in migmatite, their interpretation as true anatectic melts is not supported by the mineralogy. - 61 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 16 Photographs of shear-hosted leucogranitic injections of the Dog Lake injection complex (Stop 13). (A) Dense network of leucogranitic injections emplaced along foliation planes and dextral shear bands. Note the presence of paragneiss rafts within wider injections (B) Close-up view of dextral shear bands. Note the presence of biotite-rich schlieren in some leucogranitic injections. (C) Schlieric garnet-bearing dyke of leucogranite. Note the presence of pegmatitic pods indicating fluids segregation. (D) Close up on garnets within the dyke of leucogranitic. Melanosome-looking parts are mostly only composed of biotite and lack typical peritectic mineral phases (e.g., garnet, cordierite, sillimanite) expected from insitu partial melting of metasedimentary protoliths. Instead, this outcrop is interpreted as a migration zone for granitic melts generated deeper in the crust, which were channeled upward along regional dextral shear zones. During ascent, these melts assimilated sedimentary host rocks, resulting in the development of characteristic schollen and schlieric textures observed at this outcrop. The large volume of ascending granitic melt likely induced high-temperature, low-pressure metamorphic conditions in the surrounding paragneiss, as evidenced by the development of sillimanite–cordierite assemblages. Locally, the paragneiss also experienced limited partial melting, interpreted to have been induced by thermal input associated with the emplacement of this large volume of granitic melts. Stop 14 (Planned) - Patchy metatexites, Dog Lake injection complex 346711E 5406946N (this stop is not on Figure 1) From the previous stop, return to Highway 527 and cross the highway onto Doodie Road. Park at the entrance of the road. The outcrop is located on the north side of the road. This outcrop exposes an interlayered biotite–quartz– feldspar and garnet–biotite–quartz–feldspar migmatitic paragneiss, interpreted as a patchy metatexites (Figure 18A). Peritectic garnet is present within leucosome patches, providing clear evidence for insitu partial melting of fertile pelitic layers. The estimated melt proportion is relatively low (approximately 5–10%). - 62 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 17 Chondrite normalized rare earth element (REE) patterns of leucogranitic injections from the Dog Lake injection Complex compared with Stype granite intrusions occurring in the Quetico Subprovince. Bedding is largely preserved, indicating low melt connectivity and limited melt extraction (Figure 18B). This migmatitic paragneiss is gently folded, with fold axes plunging eastward. The east–westtrending foliation dips steeply to the north. The paragneiss is cut by boudinaged dikes of white, coarse-grained leucogranite, similar to the leucogranitic injections observed at the previous stop. This outcrop highlights a significant volumetric contrast between the limited amount of melt generated in situ within the paragneiss and the much larger volume of granitic injections observed at the previous stop (Stop 13), despite that the two localities are separated by only ~300 m. This contrast is a strong indication that the granitic melts observed elsewhere in the Dog Lake injection complex were not produced in situ but instead represent migrated and fractionated melts generated at deeper crustal levels, which were subsequently channeled upward along regional shear zones. The spatially restricted partial melting and migmatitization observed at this outcrop therefore do not represent the source of the Stype granites but rather reflect a thermal response to advected heat associated with the emplacement of large volumes of granitic melt in nearby shear corridors, rather than a widespread regional anatexis. Stop 15 (Optional) - Syn-tectonic schlieric pink monzogranite, Dog Lake injection complex 347031E 5405626N (this stop is not on Figure 1) Continue driving south along Doodie Road for approximately 1.5 km. This road is not active at the time of writing; however, road shoulders may be narrow or unstable, so vehicles should be parked directly on the road where it is safe to do so. This final stop exposes a representative outcrop of syntectonic, magnetitebearing pink monzogranite (Figure 19). The intrusion displays a heterogeneous texture, ranging from porphyritic to locally pegmatitic, highlighting the high fluid content of the granitic melt during its emplacement. The granite contains biotite schlieren, resulting of the complete digestion of the paragneiss host rock. Locally, relict structures of the - 63 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 19 Photograph of syntectonic, schlieric biotite pink monzogranite (Stop 15). Note the presence of dextral and antithetic sinistral shear bands. shear corridors. Melt migration was facilitated and channelized by regional transpressional deformation acting in the Quetico Subprovince and its adjacent greenstone belts. REFERENCES Card, K.D., and Ciesielski, A. 1986. DNAG No. 1: subdivisions of the Superior Province of the Canadian Shield. Geoscience Canada, 13: 5–13. Figure 18 Representative photographs of garnet bearing, patchy metatexites from the Dog Lake Injection Complex (Stop 14). (A) In situ partial melting localized within fertile pelitic layers of the paragneiss. Note that primary bedding structures are largely preserved. (B) Close up view of photo A. The upper layer shows a clear lack of segregation between leucosome and melanosome indicating low melt connectivity. original sedimentary bedding can still be inferred within these schlierenrich domains. The intrusion is strongly foliated and affected by welldeveloped dextral shear bands and antithetic sinistral shear bands, along which pegmatitic pods are locally emplaced. This outcrop illustrates how regional dextral shear zones within the Dog Lake complex have acted as efficient pathways for multiple types of granitic melts, which derived from different sources in the lower crust. The pink monzogranite suite is interpreted as the final, most fractionated product of the potassiumrich calcalkaline intrusive suite. These relationships reinforce the interpretation that the Dog Lake complex represents a major migration zone, where granitic magmas produced at depth were focused, transported, and emplaced along Carter, M. W., 1992, Geology and mineral potential of the Tower syenite stock, Conmee Township, District of Thunder Bay, in Dressler, B. O., Baker, C. L., and Blackwell, B., eds., Summary of field work and other activities 1992: Ontario Geological Survey Miscellaneous Paper 160, p. 60–63. Corfu, F., 2000. Extraction of Pb with artificially too-old ages during stepwise dissolution experiments on Archean zircon. Lithos, 53, nos. 3–4, p. 279–291. Corfu, F. and Stott, G.M. 1998. Shebandowan greenstone belt, western Superior Province: U-Pb ages, tectonic implications, and correlations; Geological Society of America Bulletin, v.110, p.1467-1484. Kamo, S.L. 2013. Report on U-Pb geochronology (CA-IDTIMS and LA-ICPMS) of rocks from the Grenville and Superior provinces of Ontario; internal report prepared for the Ontario Geological Survey, Jack Satterly Geochronology Laboratory, University of Toronto, Toronto, Ontario, 50p. Launay, G.A. and Metsaranta, R.T. 2023. Precambrian bedrock geology mapping in the Onion Lake and Sunshine areas, Quetico and Wawa Subprovinces, northwestern Ontario; in Summary of Field Work and Other Activities, 2023, Ontario Geological Survey, Open File Report 6405, p.11-1 to 11-12. - 64 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Launay, G.A. and Metsaranta, R.T. 2024. Mapping regional fractionation patterns in S-type peraluminous granite and pegmatite intrusions in the southern Quetico Subprovince; in Summary of Field Work and Other Activities, 2024, Ontario Geological Survey, Open File Report 6413, p.9-1 to 9-11. Lodge, R.W.D. 2014. Precambrian geology of Aldina Township; Ontario Geological Survey, Preliminary Map P.3776, scale 1:20 000. Lodge, R.W.D., 2016. Petrogenesis of intermediate volcanic assemblages from the Shebandowan Greenstone Belt, Superior Province: evidence for subduction during the Neoarchean. Precambrian Research, 272, p. 150–167. MacDonald, R.D. 1939. Gorham Township and vicinity, District of Thunder Bay, Ontario; Ontario Department of Mines, Map 48C, scale 1:63 360. Ministry of Natural Resources and Forestry 2023. Forest Resources Inventory leaf-on LiDAR; Ministry of Natural Resources and Forestry, Science and Research Branch, Forest Resource Information Unit, online data, April 10, 2022 update, https://geohub.lio. gov.on.ca/maps/lio::forest-resources-inventory-leafon-lidar/about. [accessed April 27, 2023] Metsaranta, R.T. 2015. Preliminary results from geological mapping of the Quetico Subprovince, the Shebandowan greenstone belt and Proterozoic rocks north of Thunder Bay; in Summary of Field Work and Other Activities, 2015, Ontario Geological Survey, Open File Report 6313, p.15-1 to 15-20. Metsaranta, R.T. 2022. Highlights of bedrock geology mapping in the Quetico Subprovince, north of Thunder Bay, northwestern Ontario; in Summary of Field Work and Other Activities, 2022, Ontario Geological Survey, Open File Report 6380, p.9-1 to 9-9. Metsaranta, R.T. and Walker, J.A. 2019. Precambrian geology of western McGregor Township and adjacent areas, northeast of Thunder Bay; in Summary of Field Work and Other Activities, 2019, Ontario Geological Survey, Open File Report 6360, p.11-1 to 11-10. Metsaranta, R.T. and Hamilton, M.A. 2020. A precise U/ Pb age for a north-trending mafic dike from the western flank of the Marathon swarm, East Bay area, northwestern Ontario; in Summary of Field Work and Other Activities, 2020, Ontario Geological Survey, Open File Report 6370, p.7-1 to 7-9. Metsaranta, R.T. and Kamo, S.L. 2021. A uranium–lead baddeleyite age for the Midcontinent Rift–related Lone Island Lake intrusion, northwestern Ontario; in Summary of Field Work and Other Activities, 2021, Ontario Geological Survey, Open File Report 6380, p.12-1 to 12-8. Ontario Geological Survey 2017. Ontario airborne geophysical surveys, magnetic data, grid data (ASCII and Geosoft® formats), magnetic supergrids; Ontario Geological Survey, Geophysical Data Set 1037— Revised. Pan, Y., Fleet, M.E., and Heaman, L. 1998. Thermo‑tectonic evolution of an Archean accretionary complex: U–Pb geochronological constraints on granulites from the Quetico Subprovince, Ontario, Canada. Precambrian Research, 92: 117-128. Percival, J.A. 1989. Late Archean Quetico accretionary complex, Superior Province, Canada. Geology, 17: 23–25. Percival, J.A., Sanborn‑Barrie, M., Skulski, T., Stott, G.M., Leclair, A.D., and Corkery, M.T. 2006. Tectonic evolution of the western Superior Province from NATMAP and Lithoprobe studies. Canadian Journal of Earth Sciences, 43: 1085–1115. Percival, J.A., Skulski, T., Sanborn‑Barrie, M., Stott, G.M., Leclair, A.D., Corkery, M.T., and Boily, M. 2012. Geology and tectonic evolution of the Superior Province, Canada. In: Tectonic styles in Canada: the Lithoprobe perspective. Geological Association of Canada, Special Paper 49, p. 321–378 Ratcliffe, L.M. 2016. Precambrian geology of Sackville Township, Shebandowan greenstone belt, Wawa– Abitibi terrane; Ontario Geological Survey, Preliminary Map P.3802, scale 1:20 000.Ratcliffe, L.M. 2017. Precambrian geology of Adrian Township, Shebandowan greenstone belt, Wawa–Abitibi terrane; Ontario Geological Survey, Preliminary Map P.3813, scale 1:20 000. Ratcliffe L.M. 2019. Precambrian geology of Marks Township, Shebandowan greenstone belt, Wawa– Abitibi terrane, northwestern Ontario; Ontario Geological Survey, Preliminary Map P.3830, scale 1:20 000. Rehm, A. G. 2025. “Tectonometamorphic Evolution, Fluid Production, and Evaluation of Gold Liberation in the Quetico Metasedimentary Belt, Canada.” Ph.D., Laurentian University Sudbury, Ontario. Stott, G.M., Corkery, M.T., Percival, J.A., Simard, M. and Goutier, J. 2010. A revised terrane subdivision of the Superior Province; in Summary of Field Work and Other Activities, 2010, Ontario Geological Survey, Open File Report 6260, p.20-1 to 20-10. Valli, F., Guillot, S., and Hattori, K.H. 2004. Source and tectono‑metamorphic evolution of mafic and pelitic metasedimentary rocks from the central Quetico metasedimentary belt, Archean Superior Province of Canada. Precambrian Research, 132: 53–72. Wang, S., Kuzmich, B., Hollings, P., Zhou, T. and Wang, F. 2020. Petrogenesis of the Dog Lake Granite Chain, Quetico Basin, Superior Province, Canada: Implications for Neoarchean crustal growth. - 65 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Precambrian Research, 346: 105828. 4, Part 1, p.485-541. Williams, H.R. 1991. Quetico Subprovince; in Geology of Ontario, Ontario Geological Survey, Special Volume 4, Part 1, p.383-403. Williams, H.R., Stott, G.M., Heather, K.B., Muir, T.L. and Sage, R.P. 1991. Wawa Subprovince; in Geology of Ontario, Ontario Geological Survey, Special Volume - 66 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Trip 3 - Geological assemblages, regional structural framework and tectonic evolution of the Neoarchean Shebandowan greenstone belt Dorothy Campbell, P.Geo and Justin Jonsson P.Geo Resident Geologist Program, Ontario Geological Survey, Ministry of Energy and Mines, Thunder Bay, Ontario, P7E 6S7, Canada Introduction This trip provides an overview of the geological assemblages, regional structural framework, and tectonic evolution of the Neoarchean Shebandowan Greenstone Belt (SGB) and their relationship to gold and base metal mineralization. The SGB is situated in the western Wawa Subprovince (Superior Province) and extends 150 km from the Ontario–Minnesota border in the west to northeast of Thunder Bay in the east (Figure 1). The SGB is locally in fault contact with the Quetico Subprovince to the north and bounded by the older (2750 Ma) Northern Light–Perching Gull Lakes batholith (tonalitic gneiss) and younger granitic intrusions to the south (Lodge 2016). The SGB is characterized by a complex history of early rifting, subduction-driven volcanism, tectonic accretion, and later transpressional deformation. The SGB comprises three main assemblages and two primary deformation events (Williams et al. 1991; Stott and Corfu 1991; Corfu and Stott 1998; Percival 2006; Lodge 2016; Reynolds et al. 2023; Dorval et al. 2026): BLF=Burchell Lake fault; USSZ=Upper Shebandowan Lake shear zone; SGFZ=Squeers Lake-Greenwater Lake fault zone; TLFZ=Tinto Lake fault zone; CCF=Crayfish Creek fault; LSSZ=Lower Shebandowan Lake shear zone; MLS=Moss Lake stock; BLS=Burchell Lake stock; HGC=Haines gabbroic complex; HS=Hermia stock; HLS=Hood Lake stock; GLS=Greenwater Lake stock; LGP=Little Greenwater Lake pluton; PCS=Pinecone stock; KS=Kekekuab stock; PS=Peewatai stock; SS=Shebandowan stock; TS=Tower Stock Figure 1. Regional Geology of the Shebandowan greenstone belt (modified from Kuster, Lesher and Houlé, 2022; modified from Sotiriou et al 2019; Lodge 2016; Osmani 1997a; Corfu and Stott, 1998). - 67 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Greenwater assemblage (2722-2719 Ma): volcanic suites characterized by thick sequences of tholeiitic mafic volcanic rocks, ultramafic flows (komatiites) and sills, iron formations, mafic intrusions, and minor FII- and FIII-type felsic volcanic rocks. Burchell assemblage (2719-2716 Ma): calcalkalic, dominantly intermediate volcanic rocks and lesser FI-type felsic volcanic rocks and with no known ultramafic sills or intrusions. This subdivision was first defined by Williams (1991) on the basis of younging directions but rejected by Corfu and Stott (1998) due to lack of chronological distinction and re-interpretation of structural architecture. Lodge (2016) interpreted more recent higher-precision geochronology as supporting a similar subdivision to that of Williams (1991). Kashabowie assemblage (2695 Ma): syn-D1, represents renewed activity on the SGB after a long hiatus. It is less voluminous and more evolved than Greenwater assemblage. Calc-alkaline to alkalic intermediate/felsic volcanic rocks, associated diorites, tonalites (e.g., Shebandowan Lake Pluton), tectonically interleaved with older 2720 Ma volcanic suites. This subdivision was first introduced by Corfu and Stott (1998) as part of their re-interpretation of older assemblage classifications. D1 Compressional Deformation event (2695 and 2690 Ma): associated with calc-alkaline magmatism and intra-arc deformation (thruststacking and interleaving). Shebandowan assemblage (2690-2680 Ma): syn-D2 Timiskaming-type assemblage, unconformably overlies older Greenwater assemblage, composed of calc-alkalic to alkalic volcanic rocks and associated coarse clastic Timiskaming-type sedimentary rocks, iron formation and late sanukitoid plutons. D2 Transpressional Deformation event (2685– 2680 Ma): marked the final accretionary phase of the Wawa subprovince evolution of the Superior Craton, termed the Shebandowanian phase of the Kenoran Orogeny (Stott and Corfu 1991). This late-stage dextral transpression and obliqueslip deformation represents the development of Timiskaming-type pull-apart basins and regional Timiskaming-aged structures. Auto Road assemblage (<2682 Ma): distinctly younger sedimentary assemblage in the SGB, dominated by conglomerate-sandstone units (with clasts of volcanic and granitoid origin). Corfu and Stott (1998) describe the assemblage as a small sedimentary basin, informally termed the “Auto Road assemblage”. The western limb of the SGB is often divided from the central and eastern portions of the belt by an informal north-south boundary roughly, at the town of Kashabowie (Figure 1). There are differences in the distribution of assemblages between the west and east sides: the Kashabowie assemblage is situated mostly along the western limb, the Shebandowan assemblage is situated on the central-eastern side, and the Auto Road assemblage is restricted to a small area on the eastern side. The Greenwater/Burchell assemblage(s) make up the large majority of the preserved supracrustal rocks, despite comprising just ~6 million years of the >40 million-year evolution of the SGB (Figure 1). The volcanism recorded by these assemblages appears to have been two-stage: an extensional plume-rift setting recorded by the Greenwater assemblage followed by a compressional subduction-arc setting recorded by the Burchell assemblage (Figures 2, 3; Lodge 2016). The deposition of chemically distinct Kashabowie assemblage volcanic rocks occurred after a ~21 million-year hiatus, recording a later compressional subduction-arc setting (Figure 3). These rocks are contemporaneous with the D1 structural event, which involved the interleaving and thrust-stacking of the Kashabowie and Greenwater units (Reynolds et al. 2023). Subsequently, the Shebandowan assemblage, represents the final stages of the Shebandowan accretionary event. These “Timiskaming-type,” deposits unconformably overlie the Greenwater assemblage. They are characterized by a mix of clastic sediments (conglomerate, sandstone), iron formation, and calc-alkalic to alkalic volcanic rocks (Figure 3), interpreted to have formed in transtensional, pullapart basins along the flanks of transpressional uplifts (Reynolds et al. 2023). Due to their tectonic setting, these rocks are strongly associated with structurally controlled, late-orogenic gold mineralization (Figure 4). - 68 - Based on the spatial distribution of southwest- �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 2. Schematic illustration of possible tectonic evolution of the Shebandowan greenstone belt in both plan view and crustal cross section (from Lodge 2016). Colors of units correspond to legends in Figure 1. Note sketch is not to scale. (A) Initial plume-dominated tectonic setting forming Greenwater assemblage. (B) Subduction-dominated tectonic setting forming Burchell Assemblage. A change in plate motion results in the initiation of subduction and formation of a calc-alkalic arc dominated by andesitic strata. Subduction of ridge results in high geothermal gradient and melting of slab to produce adakitic melts. Hybridization of mantle and slab derived melts results in magnesian andesites (Mg# > 50) from Lodge 2016. trending metavolcanic rocks on the western limb, Osmani (1997a) defined three distinct geological units that remain in use by current explorers (Figure 6): • Central Felsic Belt (CFB): a <5 km-wide core of the Burchell/Kashabowie assemblage. • Northern Mafic Belt (NMB) and Southern Mafic Belt (SMB): mafic metavolcanic rocks of the Greenwater assemblage, flanking the CFB to the north and south respectively. There are three past-producing mines in the SGB: the North Coldstream copper mine (1957-1967) and the Ardeen gold mine (1932-1936, 1942) in the western part of the belt, and the Shebandowan nickel-copperPGE-cobalt mine (1971-1998) in the eastern part of the belt (Figure 5). Tectonic associations provide spatial context for mineral prospectivity in the SGB (e.g. Lodge et al. 2015, Lodge 2016, Reynolds et al. 2023). Magmatic Ni-Cu-PGE mineralization occurs in the Greenwater assemblage mafic-ultramafic intrusive rocks, notably the sill-hosted deposit comprising the past-producing Shebandowan mine. The mine operated for most of 1971-1998, producing 9.29 Mt at 1.75% Ni, 0.88% Cu, 0.06% Co and 1.83 g/t PGEs. Clusters of magmatic sulfide occurrences also occur in the Haines gabbro (~7 km northwest of the mine) and in the Bateman Lake area (~40 km east of the mine). Although no economic deposits that are definitively of volcanogenic massive sulfide (VMS) affinity exist in the SGB, several prospects exist in spatial association with Greenwater/Burchell assemblage felsic metavolcanic rocks. The North Coldstream copper-gold-silver deposit, located 10 km southwest of Kashabowie on the western arm of the SGB, is a - 69 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 past-producing (2.48 Mt at 1.87% Cu, 0.28 g/t Au, and 5.53 g/t Ag from 1957-1967) atypical deposit variably interpreted to be intrusion-related (e.g. Farrow 1994) or volcanogenic (Reynolds et al. 2023); it is currently being explored by Gold X2 Mining Inc., who tentatively interpret the deposit as a sheared, remobilized VMS system. In more recent years, orogenic gold has become the main focus of mineral exploration in the SGB. Gold is primarily controlled by late tectonic D2 structural zones, in contrast to lithologically controlled magmatic and VMS mineralization associated with Greenwater/ Burchell assemblages. Gold mineralization is generally hosted within ductile-brittle shear zones, particularly near regional fault zones (Figure 4) or adjacent to “Timiskaming-type” unconformities (Figure 14). Gold is typically hosted by quartz-carbonate-pyrite veins and veinlet networks cross-cutting all lithologies. On this field trip, we will look at some specific examples these structural zones: • Moss Gold Deposit (Gold X2 Mining Inc.) and the 111 Zone (Bold Ventures Inc.): gold mineralization occurs near regional fault zones, within sheared diorites, felsic dykes/sills and mafic to intermediate metavolcanic rocks. • I-Zone (Delta Resources Limited): gold-bearing quartz ladder veins within a felsic dyke (brittle, extensional), intruding Timiskaming iron formation. • Eureka Zone (Delta Resources Limited): a key target for gold exploration at the unconformity Figure 3. Evolution of Greenwater/Burchell, Kashabowie, and Shebandowan assemblages (from Reynolds et al. 2023). Figure 4. Schematic section of western Shebandowan greenstone belt (from Reynolds et al. 2023). - 70 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 5. Geology map of the Shebandowan greenstone belt showing location of field trip stops. NCM: North Coldstream Mine, See Figure 1 for all other abbreviations. - 71 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 between the Greenwater and Shebandowan assemblages, marking a “Timiskaming-type” unconformity. Stops 1 to 2 - Moss Gold Deposit (Gold X2 Mining Inc.) Permission is required from company to access sites Gold X2 Mining Inc. (Gold X2) is exploring the Moss gold deposit, a high-tonnage low-grade deposit (Figure 6), located 100 km west of Thunder Bay on the western limb of the SGB. Gold X2 recently completed a Preliminary Economic Assessment, releasing an updated resource estimate as of January 16, 2026, (Dorval et al. 2026) for the deposit as follows: • Indicated: 2.125 Moz Au at 1.03 g/t with 3.160 Moz Ag at 1.53 g/t • Inferred: 3.910 Moz Au at 0.97 g/t Au with 6.273 Moz Ag at 1.55 g/t Engineering trade-off studies & design work is underway and a feasibility study is anticipated for Q3 2027 (Gold X2 Mining Inc., Corporate Presentation, April 12, 2026). The Moss deposit is structurally controlled and situated within intermediate to felsic metavolcanic rocks of the Central Felsic Belt (CFB; Figure 6). Primarily hosted by sheared diorite (Figure 7), the deposit developed during and after intense ductile deformation, with 2 distinct tectonic-hydrothermal events identified (Reynolds et al 2023; Dorval et al. 2026). Alteration occurs in different styles and intensities but is generally composed of albite, biotite, sericite, chlorite, carbonate, epidote and pyrite (typically 2-10% of the rock; locally up to 15%). Gold mineralization occurs in complex arrays of smallscale quartz-carbonate-pyrite veinlets, breccias, and stockworks with higher grades within more intense, narrow shear zones (Nwakanma 2024; Dorval et al. 2026). The sulfide assemblage is dominated by pyrite, with minor chalcopyrite, sphalerite, and molybdenite. Rare, high-grade tellurides are associated with the high-grade gold mineralization (Reynolds et al. 2023; Dorval et al. 2026). Stop 1. Moss Gold Deposit (Portal) N83 Z15 U 668730E 5379177N At this stop, highly sheared diorite and feldspar porphyry has been variably silicified, chloritized, hematized, sericitized and sulphidized (Figure 7). The outcrop is highly fractured and exhibits a network of narrow quartz-carbonate-pyrite veinlets. The now closed-off portal, developed in the mid-1980s by Tandem Resources Limited and Storimin Exploration Limited, lead to historical underground workings and gold zones at the 230-foot (70 m) level (Figure 8). Figure 6. Geology map shear hosted Moss Lake Deposit (in red) modified from Dorval et al. (2026). - 72 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 8. Underground plan of the 230-foot (70 m) level, showing gold-bearing zones of the Moss deposit (from Osmani 1997a; modified from an underground plan of Tandem Resources Limited - Storimin Exploration Limited, 1989). Figure 7. Gold-mineralized diorite at the Moss deposit that has been variably silicified, chloritized, hematized, sericitized and sulphidized. Stop 2. Discovery Outcrop The Moss property has a long history of exploration dating back to 1936, when Mining Corporation of Canada completed 5 trenches that exposed a zone of mineralization later known as the Main Zone (often referred to in historical records as the Snodgrass showing). Gold was initially identified in a mineralized zone hosted by sheared dacite and felspar porphyry near the northern contact with diorite. The zone measured approximately 25 feet (7.6 m) in width and 600 feet (180 m) in length. In 1945, Lobanor Gold Mines Limited followed up with 12 diamond drill holes which ultimately led to the development of the Moss deposit (Figure 9). Subsequently, more than 30 companies explored various smaller sections of the property that were consolidated in 2014-2016 by Wesdome Gold Mines Ltd. In May 2021, Gold X2’s predecessor (Goldshore Resources Inc.) acquired the Moss Gold property from Figure 9. Map showing location of initial trenches, drill holes and gold assay results by Lobanor Gold Mines (1945) (from Harris 1970). - 73 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Wesdome. In 2024-2025, the property was further expanded by: i) purchasing the “Coldstream claims” and acquiring Kesselrun Resources Ltd., whose Huronian project claims include the past-producing Ardeen mine, ii) staking the Hillcrest property (Crayfish Creek Fault extension) and claims covering the Squeers-Greenwater Fault Zone extension, to the north and south of the Moss deposit, respectively, and iii) optioning Sky Gold’s Star Lake property, based on OGS gold-in-till anomalies (Figure 10). These expanded land holdings are strategic and a testament to the importance of regional structures for gold exploration. Stop 3. 111 Au Zone Trench - Burchell Lake Au-Cu Property (Bold Ventures Inc.) N83 Z15 U 676840E 5380320N Permission is required from company to access site The Burchell Lake Au-Cu property, located 95 km west of Thunder Bay, is adjacent to Gold X2’s Moss property to the west. While the property hosts multiple Au and Au-Cu showings, this stop focuses on Bold’s newly discovered 111 Au Zone (Figure 11 and 12). Initial grab samples returned 59.9 g/t and 68 g/t Au (Figure 11). Sampling at the 111 Au Zone by the Regional Resident Geologist (2025) returned up to 61.2 g/t Au and >1.2% Cu. Early assay results from 2026 drilling at the 111 Au Zone, BL-26-001 returned 0.42 g/t Au over 19 m, including 1.1 g/t Au over 5.0 m, and 2.7 g/t Au over 1 m. At this stop, silicified mafic to intermediate metavolcanic rocks are crosscut by a northeasttrending anastomosing shear zone (Figures 11, 12). A 14 m-wide halo of anomalous gold (see red dotted outline on Figure 12) has been outlined, flanked with zinc and copper mineralization. Gold mineralization is associated with disseminated pyrite and stringers of chalcopyrite, hosted in strongly silica‑ and sericite‑altered metavolcanic rocks. Locally, the rock is characterized by intense shearing and alteration obscuring the protolith, potentially a sheared and highly silicified metavolcanic rock or diorite. A narrow, relatively undeformed felspar porphyry occurs adjacent to the shear zone (Figure 12). Osmani (1997b) mapped this location as a felsic metavolcanic-dominated portion of the Southern Mafic Belt, though there was no outcrop exposure at the 111 Au Zone at the time of his mapping. Corfu and Stott (1998) reported a U–Pb zircon age of 2721 ± 1 Ma from a felsic metavolcanic flow less than 2 km to the northeast, interpreted to represent its eruption age. The mafic metavolcanic Figure 10. Map showing Gold X2’s 2025-2026 land acquisitions: Kesselrun’s Huronian project with the past-producing Ardeen Mine (red oval), Hillcrest and Squeers-Greenwater projects (yellow ovals), and Sky Gold’s Star Lake property (blue) with a cluster of gold in-till anomalies (orange and yellow dots). - 74 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 11. Map of land position, major showings, and 111 Au Zone trench highlighted with red oval (from Bold Ventures Inc., news release, October 20, 2025). Figure 12. Geology map showing the 111 Au Zone with channel sample results for gold, copper and zinc (from Bold Ventures Inc, news release, October 20, 2025). - 75 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 rocks here may either be tectonically interleaved with or conformable with the felsic metavolcanic rocks mapped by Osmani (1997b). Stop 4. Pillowed vesicular basalt at Swamp River N83 Z15 U 714018E 5390896N This outcrop is an example of typical Greenwater assemblage tholeiitic mafic metavolcanic rocks. The outcrop is glacially polished with well-defined striations that trend 25°. Glassy pillow selvages and abundant vesicles are well preserved at this location. Pillows are deformed (~10:1 aspect ratio) in the same orientation as foliation, striking 100° and dipping steeply south. Original mineralogy is replaced by a typical greenschist facies assemblage of chlorite, hornblende, sericite, saussurite, and carbonate (Morin, 1973). Pillow selvages appear to have been loci for fluid movement, as evidence by localization of pyrite and carbonate to the selvages. Morin (1973) mapped these pillows as younging to the north-northeast – can you see this? Stop 5. Timiskaming-type conglomerate N83 Z15 U 715392E 5387505N From Aubet and Campbell (2012). At this location two facies of the epiclastic suite of Timiskaming-type rocks are exposed. The dominant rock type is poorly sorted, highly foliated conglomerate (Figure 13). Note the heterolithic nature of the fragments, including minor Keewatin-type red jasper fragments. This particular outcrop is highly deformed with the clasts being stretched, forming a welldeveloped lineation plunging steeply to the southeast. Note the abundant iron carbonate alteration within the sandy matrix. In fault contact with the conglomerate to the west are mudstone and siltstone. Here we have near vertical mineral lineations normal to rolls on the bedding planes. This unit is finely bedded with grading, although present, obscured by the deformation. Stop 6. Autoclastite N83 Z15 U 715698E 5385810N This location is an example of ultramafic metavolcanic rocks of the Greenwater assemblage, featuring a flow-top breccia with a mixture of transported sub-angular, blocky clasts exhibiting some nice examples of random spinifex-textures and Figure 13. Timiskaming Conglomerate variolitic textures. The clasts range in size from 0.5 cm to 20 cm in diameter. Although this particular outcrop was not mapped by Rogers (1995), Rogers and Berger (1995) reported other nearby ultramafic metavolcanic units to be generally narrow (<50 m thick) and discontinuous (<1 km along-strike). Both olivine and pyroxene spinifex have been reported in the eastern SGB (e.g. Hinz 2018). Stops 7 to 10. Delta-1 Au Property (Delta Resources Limited) Permission required from company to access sites The Delta-1 Gold property (formerly Shabaqua Gold Project) is located near Shabaqua, 50 km west of Thunder Bay. The area has a long history of exploration dating back to 1930s, where numerous companies and prospectors carried out prospecting, geological, geochemical, and geophysical surveys, trenching, sampling and diamond drilling programs. While the Eureka deposit is the company’s flagship, Delta Resources significantly expanded the Delta-1 property in 2024 by acquiring more than a dozen properties from numerous companies and prospectors. The Delta-1 property now has multiple gold prospects and occurrences covering a 35-km strike extent of several regional-scale structural zones, near or at the unconformity between Shebandowan (Temiskaming- - 76 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 type) metasedimentary rocks and Greenwater metavolcanic rocks (see black dotted lines in Figure 14). (Portofino Resources Inc., news release, November 17, 2020). Stop 7. I-Zone gold-bearing quartz ladder veins N83 Z15 U 714705E 5382490N Modified from Aubet and Campbell (2012) The I-Zone (and associated gold showings) is an exploration target situated proximal to the Crayfish Creek Fault (Figure 14), a major regional structure currently presenting as brittle but likely with a protracted brittle-ductile history. The I-Zone gold occurrence consists of felsic dikes intruding Timiskaming oxide facies iron formation intercalated with argillite. The felsic dikes are host to gold-bearing quartz-tension/ ladder veins with 3%-5% pyrite and localized visible gold (Figure 15). Fractures opened up in the dike due to the ductility contrast of the enclosing ironrich argillites and the felsic dike. Later hydrothermal fluids, likely carrying gold reacted with the iron oxides resulting in the formation of pyrite and precipitation of native gold. Historical findings at the site include Landore Resources’ 1995 drill program, which intersected 4.32 g/t Au over 41 m, 4.53 g/t Au over 14.4 m, and 4.36 g/t Au over 20.4 m. Additionally, a 2008 mini-bulk sample conducted by Mengold Resources yielded an average grade of 9.9 g/t Au. Portofino Resources Inc. reported 2020 sampling at the I-Zone returned up to 45.9 g/t Au with 6 of 14 samples returning more that 5 g/t Au Figure 15. Simplified geology at the I-Zone (modified from Aubut et al., 1990). Stop 8 Eureka Zone (2024 Delta-1 Eureka Trench above drill hole D1-23-60) N83 Z16 U 290200E 5385348N In 2017, Doug Parker and Barbara D’Silva generated renewed interest in gold exploration in the Shabaqua area, on the eastern limb of the SGB. The ParkerD’Silva team followed up on historical data and OGS gold-in-till anomalies with prospecting, mechanical stripping, and rock sampling, which successfully led to the discovery of the Eureka Gold Zone (Figure 16). In 2019, Mr. Parker optioned the property to Delta Resources Inc. (Delta). Since then, Delta has advanced the project with 140 diamond drill holes (totaling more 40 000 m), confirming a mineralized zone for more than 2.5 km along strike and to a depth of 400 m (Figure 17). The Eureka Zone is situated adjacent to the unconformity between Shebandowan (<2690 Ma) and Greenwater (2720 Ma) assemblages. The Figure 14. Geology map showing Delta 1 Gold property (black outline), regional structural zones (black dashed lines) and gold showings (red stars) situated at or near the uniformity between Greenwater-Shebandowan assemblages (from Delta Resources Inc. website, Projects; Delta-1; Regional and Property Geology, April 2026). - 77 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 ankerite-pyrite veinlets. The quartz-ankerite-pyrite gold veinlets crosscut all lithologies and are hosted within a 300-400 m wide corridor of ankerite-silicasericite altered rocks. The Greenwater assemblage host rocks at this stop are comprised of mafic metavolcanic and ultramafic flows, weathered to a dark rusty brown with rock textures nearly or completely obliterated (Figure 18). Stop 9. Bylund Trench N83 Z15 290490E 5385211N Figure 16. Doug Parker’s 2017-18 prospecting and mechanical trenching programs generated renewed interest in gold exploration in the Shabaqua area. unconformity between the Greenwater (ultramafic and mafic to intermediate metavolcanic rocks) and Shebandowan (Temiskaming-type metavolcanic and metasedimentary rocks) assemblages has a close spatial association with gold occurrences, widely known as prospective for gold exploration (Figure 14). At this stop, Delta’s 2024 trenching program exposed an 11 m surface section of the Eureka Gold Zone, directly above drill hole D1-23-60. This drill hole returned an intersection of 1.79 g/t Au over 128.5 m (including 2.16 g/t Au over 97.5 m), while channel sampling from the surface trench returned an average grade of 1.23 g/t Au over 11 m (Delta Resources Inc., news releases, September 12, 2023, and September 25, 2024). Gold mineralization at the Eureka Zone is hosted by a stockwork of 1 mm to 10 cm wide quartz- At this stop, stockworks of gold-bearing quartzankerite-pyrite veinlets are situated within a broader 300-400 m carbonate-sericite-silica-altered halo that hosts anomalous/low-grade gold mineralization. The mineralized trend strikes ~110° and dips approximately 50-55° north. Mineralization is hosted within Greenwater assemblage rocks – most commonly, a feldspar-phyric tholeiitic basalt. That unit is not seen at this trench; what we see here a silica-rich rock that has historically been interpreted as chert but is being re-evaluated by the company as at least partially comprising highly silicified metavolcanic rocks. On the northeastern end of the trench, silicified komatiite or komatiitic basalt is present, displaying beautiful spinifex texture. Intense pyrite-ankerite alteration is widespread, but gold grades from this trench are relatively low. Three generations of quartz-carbonate veins are visible at this trench: i) NE-trending, steeply NW- Figure 17. Longitudinal section of the Eureka Zone - 78 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 18. Eureka Zone stockwork of 1 mm to 10 cm wide gold-bearing quartz-ankerite-pyrite veinlets hosted by Greenwater assemblage rocks are weathered to dark rusty brown with rock textures nearly or completely obliterated. dipping, ii) NW-trending, steeply dipping, and iii) NE-trending, shallowly dipping. Vein sets 1 and 2 are conjugate and are post-dated by vein set 3. Vein set 1 is the main gold-bearing set. Stop 10. Finmark Metasedimentary Rocks N83 Z16 U 293525E 5383950N From Puumala and Cundari (2023) At this stop we will have an opportunity to view a remarkably well-preserved roadside exposure of Shebandowan assemblage clastic metasedimentary rocks. The following description of these rocks is provided by Carter (1990). The rocks are mainly thinly bedded, the beds ranging in thickness from 5 cm to 12 cm. Primary sedimentary structures comprising load casts and flame structures, small-scale ripple structures, and cross bedding, are well developed in these rocks in the road exposures along Highway 11- 17 about 2.5 km west of the eastern boundary of Horne Township, and in the outcrops immediately southeast of these. Parker (1980) indicates that the “Finmark metasedimentary belt” consists of sandstone-siltstonemudstone sequences that alternate with thick units of cross-stratified sandstone. These sequences display many of the primary sedimentary structures that are characteristic of tidal flat (e.g., rhythmic layering, lenticular, wavy and flaser bedding) and tidal channel (e.g., herringbone cross stratification, large scale crossstratification) depositional environments respectively. Petrology of these rocks indicates that the primary sediment source was a felsic to intermediate volcanic terrain (Parker 1980). Characteristics of the clasts and rock fragments are consistent with a proximal Shebandowan assemblage sediment source. - 79 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Stop 11. Auto Road Assemblage (Optional) mafic clasts to nearly undeformed. N83 Z16 U 313838E 5377726N The Auto Road assemblage comprises a small sedimentary basin in south-central Ware township. It was first provisionally subdivided by Corfu and Stott (1998) on the basis of a U-Pb in youngest detrital zircon age of 2682±3 Ma – this is 9 m.y. younger (and outside of error provisions) than the youngest detrital minerals (zircon and titanite) in the Shebandowan assemblage. The assemblage is affected by D2 deformation and therefore provides a lower constraint on both sedimentation and regional transpression in the SGB. Corfu and Stott (1998) comment: The map pattern suggests that this conglomerate-sandstone unit is interbedded with Greenwater assemblage basaltic units (Brown, 1995), yet the polymictic conglomerate includes feldspar-hornblende-phyric volcanic clasts typically found within the Shebandowan assemblage. Also common are coarse granitoid cobbles as well as clasts of various volcanic lithologies. The results for sandstone sample Au presented below demonstrate that this is indeed one of the youngest supracrustal units of the Shebandowan greenstone belt as well as of the neighboring Quetico Subprovince, justifying its separate designation. Acknowledgements We would like to thank Gold X2 Mining Inc., Bold Ventures Inc., and Delta Resources Limited for permission to access parts of their properties and for their generous time, knowledge and support in preparing for this field trip. REFERENCES Aubet, A. and Campbell, D. 2012. Field trip 4 - Shebandowan Mine Area In; Hollings, P., MacTavish, A. and Addison, W. (Eds.), Institute on Lake Superior Geology Proceedings, 58th Annual Meeting, Thunder Bay, Ontario, Part 2 - Field trip guidebook, v.58, part 2, 2-26. Aubut, A., Lavigne Jr., M.J., Scott, J. And Kita, J. 1990. Metallogeny, Stratigraphy and Structure of the Shebandowan Greenstone Belt; Field Trip 3 Guidebook, Mineral Deposits of Central Canada, CIM Thunder Bay Branch. Campbell, D.A. and Rainsford, D.R.B. 2020. Nickelcopper-cobalt-PGE potential in the Shebandowan greenstone belt; in Ontario Geological Survey, Resident Geologist Program, Recommendations for Exploration 2019–2020, p.69-74 At this location, felsic intrusive, chert, and felsic to mafic intrusive clasts of up to 40 cm in size are deformed (up to ~5:1 aspect ratio) by D2 transpression. Mafic clasts are deformed to a roughly uniform degree, while felsic clasts vary from similarly deformed as Carter, M.W. 1990. Geology of Goldie and Horne townships; Ontario Geological Survey, Open File Report 5720, 189p. Corfu, F. and Stott, G.M. 1998. Shebandowan greenstone belt, western SuperiorProvince: U–Pb ages, tectonic implications, and correlations. GSA Bulletin 110,1467–1484. Dorval, A., Lussier, D., Michaud, C., Taschereau, C., Vanier-Larrivée, N., Shankie, S. 2026. Preliminary Economic Assessment NI 43-101 Technical Report, Moss Gold Project, Ontario Canada, prepared for Gold X Mining Inc. by G. Mining Services Inc. Farrow, C.E.G. 1994. Base metal mineralization, Shebandowan greenstone belt, District of Thunder Bay in Summary of Field Work and Other Activities 1994, Ontario Geological Survey, Miscellaneous Paper 163, p. 22-97 to 22-104 Harris, F.R. 1970. Geology of the Moss Lake area, Ontario Geological Survey, Geological R085, 89p. Hinz, S.L.K. 2018. Geochemistry and petrography of the ultramafic metavolcanic rocks in the eastern portion of the Shebandowan greenstone belt, northwestern Ontario; Lakehead University, unpublished MSc thesis, 157p. Figure 19. Polymictic conglomerate of the Auto Road assemblage. Inco Limited Ontario Division 2001. Shebandowan Mine closure plan Part I of II: unpublished report; Ministry of Energy and Mines, Thunder Bay Mining Division; - 80 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Thunder Bay District, 84p. Survey, Special Vol. 4, Part 1, pp.145-238. Kuster, K., Lesher C.M., and Houlé, M.G. 2022. Geology and geochemistry of mafic and ultramafic bodies in the Shebandowan mine area, Wawa-Abitibi terrane: implications for Ni-Cu-(PGE) and Cr-(PGE) mineralization, Ontario and Quebec, Geological Survey of Canada Scientific Presentation 130, 25p. Lodge, R.W.D., Gibson, H.L., Stott, G.M., Franklin, J.M. and Hudak, G. 2016. Geodynamic setting, crustal architecture, and VMS metallogeny of ca. 2720 Ma greenstone belt assemblages of the northern Wawa subprovince, Superior Province. Canadian Journal of Earth Sciences, vol. 52, p. 196-214. Lodge, R.W.D. 2016. Petrogenesis of intermediate volcanic assemblages from the Shebandowan greenstone belt, Superior Province: Evidence for subduction during the Neoarchean: Precambrian Research, v.272, p.150–167. Morin, J.A. 1973. Geology of the Lower Shebandowan Lake area, District of Thunder Bay. Ontario Geological Survey, Report 110, 45p. Nwakanma, M.U. 2024. Characterization of alteration and mineralization of the Moss gold deposit, Shebandowan greenstone belt, Northwestern Ontario, Lakehead University, Department of Geology, Masters Thesis, 173p. Osmani, I.A., 1997a. Geology and mineral potential: Greenwater Lake area, west-central Shebandowan greenstone belt; Ontario Geological Survey, Report 296, 135p. Osmani, I.A. 1997b. Precambrian Geology, BurchellGreenwater Lakes area, west half; Ontario Geological Survey, Map 2622, 1: 20 000. Parker J. R. 1980: The Structure and Environment of Deposition of the Finmark metasediments, Thunder Bay, Ontario. Unpublished Hon.B.Sc. Thesis, Lakehead University, Thunder Bay, Ontario, 90 p. Percival, J.A., Sanborn-Barrie, Skulski, T., M., Stott, G.M., Helmstaedt, H., and White, D.J. 2006. Tectonic evolution of the western Superior Province from NATMAP and Lithoprobe studies. Geological Survey of Canada, NRC Research Press Web site at http:// cjes.nrc.ca.on 4 September 2006. Puumala, M. and Cundari, R. 2023. Geological highlights of the Thunder Bay area, Thunder Bay South Resident Geologist’s Office, unpublished field trip guide, 23p. Reynolds, N., Field, M., Fung, N., Peruse, C., Raponi, R., Ugarte, E., Gupta, N. 2023. NI 43-101 Technical report mineral resource estimates for the Moss Gold and East Coldstream deposit, Ontario, Canada, prepared for: Goldshore Resources Inc., 285p. Rogers, M.C. 1995. Precambrian geology, Duckworth township; Ontario Geological Survey, Map 2621, 1:20 000. Rogers, M.C. and Berger, B.R. 1995. Precambrian geology, Adrian, Marks, Sackville, Aldina and Duckworth townships. Ontario Geological Survey, Geological Report 295, 66p. Williams, H.R., Stott, G.M., Heather, K.B., Muir, T.L. and Sage, R.P. 1991. Wawa Subprovince; in Geology of Ontario, Ontario Geological Survey, Special Volume 4, Part 1, p.485-541. Sotiriou, P., Polat, A., Frei, R. 2019. Petrogenesis and geodynamic setting of the Neoarchean Haines Gabbroic Complex and Shebandowan greenstone belt, southwestern Superior Province, Ontario, Canada: Lithos, v.324-325, p.1–19. Stott, G.M. and Corfu, F.1991.Uchi subprovince. In Geology of Ontario. Edited by P.C. Thurston, H.R. Williams, R.H. Sutcliffe, and G.M. Stott. Ontario Geological - 81 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Trip 5 - Archean Geology and Metallogeny of the Rainy Lake Wrench Zone K. Howard Poulsen Geological Consultant USA. It includes approximately 2600 km of rocky shoreline plus more than 1600 islands and covers an area of approximately 930 square kilometers. Rainy Lake is fed from the east by the Seine River waterway and is drained westward by the Rainy River which leads to the even larger Lake of the Woods and the Winnipeg River system (Fig. 1). For centuries it has been part of the historic water link between the Atlantic and Arctic watersheds: it was known as Tekamaniwen to the indigenous inhabitants of the region and as Lac a la Pluie to the French voyageurs and fur traders. Rainy Lake and Lake of the Woods are remnants of the vast glacial Lake Agassiz which formed by melting of the Wisconsin continental ice sheet approximately 13,000 years ago. The predominately Archean bedrock in the Rainy Lake region (Figs. 1, 2) is now exposed in arched, glacially-sculpted outcrops within areas of generally thin and discontinuous surficial cover overgrown by boreal forest. A little learning is a dangerous thing; Drink deep, or taste not the Pierian spring: There shallow draughts intoxicate the brain, And drinking largely sobers us again. Fired at first sight with what the Muse imparts, In fearless youth we tempt the heights of Arts, While from the bounded level of our mind Short views we take, nor see the lengths behind; But more advanced, behold with strange surprise New distant scenes of endless science rise! So pleased at first the towering Alps we try, Mount o’er the vales, and seem to tread the sky, The eternal snows appear already past, And the first clouds and mountains seem the last; But, those attained, we tremble to survey The growing labors of the lengthened way, The increasing prospects tire our wandering eyes, Hills peep o’er hills, and Alps on Alps arise! Alexander Pope, 1711 Foreword Rainy Lake is a body of fresh water which straddles the border between Ontario, Canada and Minnesota, My first visit to Rainy Lake was in summer 1966 when I helped a geophysical operator evaluate the longwire electromagnetic survey method for our employer Dr. Ray Oja, a geological consultant working out of Thunder Bay. The equipment test was focused on the Grassy Portage Bay property of Noranda Mines Ltd. which included copper mineralization on their Halkirk Figure 1: Southwestern Superior Province with locations of selected mineral deposits. The area of Figure 2 is outlined by the dashed rectangle. - 82 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 2: Rainy Lake Geology – Watten (Northrock) prospect: C.J. Hodgson who later became one of my thesis supervisors at Queen’s had completed his MSc thesis on this deposit in 1959. I returned to the property in the early 1970’s with Dr. Mel Bartley who was then consulting for Northrock Mines and I helped him log a section of diamond drill core from the deposit which is located on the south flank of a feature known as the Rice Bay Dome (Fig. 2). Mel, who was a well-regarded geologist and one of the founders of Lakehead University, also consulted around that time for George Armstrong of Fort Frances. George was a successful highway construction contractor who, along with Mike Hupchuk, was also an avid part-time prospector. They had discovered Zn mineralization in 1971 near Pocket Pond east of Rice Bay. Mel and I made a site visit to Pocket Pond in fall 1972 and I prepared a report on the geophysical data for the property (Poulsen, 1973). At that time, I noted the existence of abundant outcrops along the drill roads near Armstrong’s trenches which were extremely large for the time - they had been excavated by his road construction crew! Jim Franklin, for whom I had been a research assistant at Lakehead University, left in July 1975 to join the GSC in Ottawa while I became a full-time technician in the geology department. I also began an independent look at roadside outcrops around Thunder Bay with a view toward identifying a possible thesis topic with Dick Ojakangas, the well-regarded sedimentologist at Duluth who was also famous for his Finn jokes. Around the same time, however, I told Jim about the interesting geology and the massive sulfide mineralization at Rainy Lake and we decided to investigate further. Armed with Andrew C. Lawson’s classic GSC Memoir 40 as well as Fred Harris’ more recent Ontario geology maps as guides, we visited several outcrops on Rainy Lake in summer 1976. In particular we revisited the Pocket Pond property where we confirmed my original observation that, based on pillow shapes, the strata appeared to be overturned. We also visited Lawson’s classic outcrops at Bear’s Passage using a Zodiak boat only to realize when we got there that they now are located at a boat launch site which is easily accessible by road! We nonetheless had also found the key outcrops and agreed that the staurolite-bearing metasedimentary rocks are also overturned. We later met John Wood of the Ontario Geological Survey who was mapping to the east at Mine Centre and he showed us outcrops of Lawson’s Seine conglomerate and of gold-bearing quartz veins near Bad Vermilion Lake. Once Lakehead University gained approval for its own M.Sc. program in geology, I applied to become the first (part-time) graduate geology student at Lakehead to study the problem of the apparently - 83 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 overturned stratigraphy around the Rice Bay Dome and Bear’s Passage. The thesis work began in 1978 under the supervision of Manfred Kehlenbeck and the newly hired structural geology professor, Graham Borradaile. The resulting structural analysis showed that, contrary to the long-standing interpretation of the Rice Bay Dome as originally proposed by Lawson, the evidence was clearly in favour of downward facing folds and extensive stratigraphic inversion but it was not easy to convince others of this: I had, somewhat unwittingly, stumbled into a larger problem that had already dominated the discussion of the Archean rocks northwest of Lake Superior for many decades. The Institute on Lake Superior Geology was initiated in 1955 as an annual meeting, most times with companion field trips, to discuss developments in geological understanding of both the U.S. and Canadian side of Lake Superior. Early meetings emphasized iron ore deposits which were of the greatest economic importance at that time but evolved into an exploration of a much more eclectic range of topics. Mel Bartley and Ed Pye of Port Arthur were among the early participants and Samuel S. Goldich, a pioneer of geochronology, was a founder and frequent contributor. I attended my first ILSG meeting at Madison, Wisconsin in 1973. Among the speakers were Paul Sims and Klaus Schultz of the U.S. Geological Survey and Don Davidson and John Green of the University of Minnesota at Duluth. A memorable and perhaps prophetic moment came during a presentation on Proterozoic stratigraphy of the Lake Superior area by the mild-mannered John Green who suggested that the Puckwunge Formation should be excluded from the Keweenawan Group. The proposal brought loud and angry condemnation by the short, red-faced Sam Goldich even before the talk was completed. As it turns out, although Goldich was a painfully shy and quiet individual in social situations, he was equally fierce and combative in professional settings. This proved to be the case again in 1976 at the ILSG meeting at St. Paul Minnesota. I attended Goldich’s excellent field trip to the Archean gneisses of the Minnesota River Valley, including a visit to a small outcrop in a swamp where he believed he had sampled and analysed the oldest rock on Earth as reported by that time. When one of his former graduate students questioned the statistical validity of Goldich’s data regression, the offender was told in no uncertain terms that, if he didn’t like the method, he could just leave the field trip immediately! At that time Goldich was a member in high standing of an international group of geologists with a strong interest in Precambrian geochemistry and geochronology. The Canadian leader within this group was Alan M. Goodwin of the University of Toronto who had conceived of and organized the multidisciplinary Superior Geotraverse Project which ran from 1970 to 1978. Near the project’s end Goodwin organized the Archean Geochemistry Conference in summer 1978 to highlight the significant results. This meeting involved the “who’s who” of Precambrian geochemistry at the time and, after a series of conference presentations at the Quetico Centre, the group headed west to Fort Frances-International Falls. Sam Goldich and Zell Peterman led a one-day field trip on route to illustrate aspects of the geology at Rainy Lake. Peterman had completed his MS thesis with Goldich in 1959 on the metasedimentary rocks of the Rice Bay Dome and now was a geochemist with the US Geological Survey in Denver. With prior arrangement by Jim Franklin who was a formal participant, I was able to tag along unofficially and silently as a beginning graduate student. The emphasis at each stop was placed on the chemical composition of rock units as recorded on hand-written file cards which Goldich drew from a deck at each outcrop. At one exposure there was considerable debate about whether a xenolith-rich lamprophyre dike might actually be a new locality of the Seine conglomerate but the important localities at Bear Passage and Pocket Pond were not part of the field trip. The classical stratigraphic interpretation of the eminent geologist Andrew C. Lawson was adhered to and I was not in any position to offer an objection. I made my first formal presentation on “Polyphase Deformation of Archean Rocks at Rainy Lake, Ontario” on May 10th of the following year at the Institute of Lake Superior Geology meeting at Duluth where I made the case for overturned strata around the Rice Bay Dome, contrary to Lawson’s original interpretations. Sam Goldich, who often referred reverently to “Professor Lawson”, was upset by this, so much so that he was unable to speak to me about it in person: he sent a delegation of Zell Peterman and Paul Sims instead to voice his displeasure. Both were apologetic and conciliatory and asked if it would be possible for me to arrange a field trip to visit the outcrops in question and this was set for later in the summer. In addition to Goldich, Sims and Peterman, the field trip participants included Dick Ojakangas - 84 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 and David Southwick from Minnesota as well as the Ontario geologists John Wood, Charlie Blackburn and Dick Beard. The event did not start well with Goldich clearly muttering something to the effect of “young punks don’t know anything” but the situation improved somewhat with successive stops. The second to last was at Lawson’s famous Bear’s Passage exposure: the group hadn’t fully had a chance to look closely at the outcrop before Dick Ojakangas, with a pointing of his thumb, indicated the southwestward direction of younging of the northwestward-dipping graded beds. This prompted Goldich to become agitated and declare that he didn’t believe graded bedding was a reliable criterion: Ojakangas, who had completed his PhD on the Cretaceous turbidites of the Great Valley Sequence in California, responded calmly that he had measured at least a thousand similar beds there without conflict. The final stop was at the exposure of pillow basalt near Pocket Pond where the field relationships proved to be even more convincing. Paul Sims, a nononsense individual whose standard dinner included a martini, a rare steak and a salad, followed by a footlong cigar, had remained quiet throughout the day but, when confronted with the outcrop, he turned to Goldich and said “there’s no question about this Sam, the section is overturned”. This prompted Goldich to smile, walk over and shake my hand, saying “well young man, you showed me something important today that I didn’t know before – let’s go back to Fort Frances and drink some of that “Canadian” beer”. He was always cordial to me from that point onward and made a point of connecting again in the field the following season. That one-day field trip was essential in demonstrating the credibility of the field observations and a second presentation on overturned Archean successions at the 1980 ILSG meeting at Eau Claire met with little resistance. A companion journal paper which previously had been rejected by the editor was ultimately accepted for publication with minor revisions by the Canadian Journal of Earth Sciences on June 17, 1980. The involvement of representatives from the Ontario and Minnesota geological surveys also proved to be important. Charlie Blackburn and John Wood later asked me to incorporate many of the field stops into one leg of a multi-day OGS-led excursion on Western Wabigoon Geology for the May 1982 GAC Meeting at Winnipeg. Dick Beard also lobbied hard for the funding of my subsequent work for Sandy Colvine of the Mineral Deposits Section of the OGS on the mineral deposits of the Mine Centre-Fort Frances area. Much of the field work for the OGS had been completed by 1981 and formed the basis of a third ILSG presentation at International Falls in 1982. Dave Southwick of the Minnesota survey was the organizer of the meeting and late in 1981 asked me if I would lead a related field trip focussed on the mineral deposits of the area. I agreed and we set a limit of 25 participants but this was a period of renewed in interest in gold exploration so registration quickly filled up. Dave contacted me again in the New Year and asked if we could double the limit to 50 participants and I reluctantly agreed but that limit was also reached in a short time so Dave developed a waiting list which grew to more than 20 requests. He contacted me once more to ask whether I would accommodate additional participants if he could find a Greyhound bus and provide shuttle vans and drivers to speed up the logistics at some field stops. I once again agreed and an exhausting, but gratifying, one-day, 10-stop field trip was delivered to 77 participants on May 5, 1982. Two weeks later, John Wood and I also led a field trip with a structural-stratigraphic focus as part of the larger excursion organized by Charlie Blackburn for the Winnipeg meeting. What follows is an attempt to illustrate the historical development of ideas about Rainy Lake geology using outcrops in the Mine Centre – Fort Frances corridor (Fig. 2). It includes a concise historical overview and a summary account of the highlights of the regional geology followed by updated descriptions of representative field localities. The motivation for doing this involves three main considerations. The first is purely practical and involves the precision and accuracy of outcrop locations. After the passage of more than forty years, some of the sites described in the guidebooks of 1982 are difficult to re-locate, especially for someone without prior knowledge of the area. Most mapping at that time was largely carried out on nonrectified aerial photographs with considerable local distortion and the modern digital tools of geographic positioning were not available. Furthermore, destruction of vegetation in some areas and new growth in others has rendered past bush trails and landmarks to be obscure, if not impossible, to recognize, even for the author of the guidebooks. Abandonment of old bush roads has also given way to new gravel access roads and the widening of highways has compromised some outcrops while exposing new ones. A second consideration is the currency of information and ideas. - 85 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 The work in the late 1970’s and early 1980’s was done within a limited context without much consideration of comparable situations globally: this is somewhat ironic because one of Lawson’s goals had been to use this region as a global type example of an Archean granitegreenstone belt. It is also important to recognize that new contributions have been made to the understanding of the geology of this area since the original guidebooks were written. The final consideration is historical. In its time the “Seine-Coutchiching problem”, rooted in the simple but laborious task of geological field mapping, influenced discussions among geologists world-wide but many of the details about the background to the debate have not been adequately recorded, especially in the context of the outcrops themselves. Every effort has been made to avoid duplication of points which are adequately covered in the past guidebooks for this region and the material presented below is meant to serve mainly as a source of information for field trip leaders and new researchers to draw on to supplement the existing documents. The Seine-Coutchiching Problem The discovery of gold at Lake of the Woods in 1878 followed by the building of the C.P.R. line prompted Arthur Selwyn, director of the Geological Survey of Canada, to instruct one of its senior mappers to begin a survey of the geology of this area. Part of the task given to Robert Bell and his young assistants, A.C. Lawson and J.W. Tyrell, was to have the geology carefully worked out as a type locality for the “socalled Huronian system” (Zaslow, 1975, p. 184). Bell left Lawson and Tyrell at Bigstone Bay in spring 1883 to map the shoreline geology and topography while he Figure 3: Simplified geology of the Coutchiching Rapids area using the colour scheme of Figure 2. surveyed a line northward toward Red Lake. When he returned, he checked their results and directed them to work separately, Lawson on geology and Tyrell on topography, before they all reconvened at Rat Portage (now Kenora) at the end of the season. By the beginning of the 1884 field season, Andrew Cowper Lawson had graduated from the University of Toronto with the gold medal in natural science and was put in charge of the project. By then, at age 23, he had been taken on staff at the Geological Survey of Canada and, during that field season, he continued the geological work at Lake of the Woods. A.E. Barlow and W.H.C. Smith independently mapped the topography southward toward Rainy Lake. Lawson’s geological report and maps resulting from the work conducted at Lake of the Woods were published in 1885, questioning the approach the Survey had taken in the mapping Precambrian rocks up to that time (Zaslow, 1975). Lawson (1885) argued that the greenstone which he termed “Keewatin” is clearly intruded by foliated granitoid rocks. He termed these “Laurentian” in keeping with the original GSC terminology introduced by its first director W.E. Logan to denote quartzo-feldspathic basement gneiss upon which all supracrustal rocks had been deposited. Although Lawson’s productivity was admired, his geological interpretations were doubted by more senior geologists. Perhaps because of the attention he gained and the fact that he had by now received an M.A. from the University of Toronto, Lawson was able to prevail on Selwyn to support his further academic advancement. He was allowed to attend courses during the winter in the U.S.A.: he was the first of many GSC geologists to follow this course of action for decades to come. Lawson, with Smith as topographer, began by mapping the canoe routes between Lake of the Woods and Rainy Lake in 1885 and in 1886 focussed on systematic mapping of the Rainy Lake area (Fig. 2). The following season, Lawson filled in the details in the Rainy Lake district while Smith moved eastward along the Seine River Route and southward to the Canada-U.S. border. Lawson recognized a series of metasedimentary rocks exposed along the Coutchiching rapids at the outlet of Rainy Lake into Rainy River at modern-day Fort Frances and International Falls (Fig. 3). He traced these rocks farther northeastward from the type locality into the Rice Bay and Bear’s Passage areas (Figs. 4, 5) where the evidence suggested that rocks of the Coutchiching series are even older than the Keewatin (Fig. 6a). This - 86 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 4: Simplified geology of the Rice Bay area only added further to his dispute with GSC management leading to the heavy editing of his map and first report on Rainy Lake geology (Lawson, 1888). He also provided additional evidence that, rather than being a fundamental basement gneiss, the Laurentian rocks are actually deformed and metamorphosed intrusions that show evidence of cross-cutting the supracrustal rocks. A hand-written version of the report was also submitted for his PhD thesis at John’s Hopkins University (Lawson (1888) where he applied the relatively new technique of optical petrographic description to thin sections from his field samples. Although the accomplishments of Lawson and his colleague W.H.C. Smith were significant, it was the resulting geological interpretation that met continued Figure 5: Simplified geology of the Bear’s Passage area. Note that “Bear’s Passage” refers to the strait linking Swell Bay to Redgut Bay but the terms “Bear Pass” or “Bear Passage” have also been used over time to describe the nearby area. resistance from management and the 1887 report was heavily edited (Saslow, 1975). Lawson, however, largely prevailed and showcased his results at the Fourth International Geological Congress at London in 1888 and the American Association for the Advancement of Science meeting at Toronto in 1889. During the 1889 field season Lawson completed the mapping of the Hunter Island Sheet southeastward of Rainy Lake with Smith but resigned from the Geological Survey of Canada in spring 1890. He worked for a while as a geological consultant in Vancouver but soon accepted a faculty position at the University of California at Berkley, where he pursued an illustrious career for the Figure 6: Portrayals of stratigraphic order at Rainy Lake (1887-1999). - 87 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 next sixty years. Although increasingly accepted overall, some aspects of Lawson’s interpretation of Rainy Lake geology continued to be questioned by his peers. In particular, Coleman (1898) noted that the sedimentary sequence at Shoal Lake (Fig. 7), portrayed by Lawson as belonging to the Coutchiching, includes conglomerate with abundant rounded clasts of both Keewatin greenstone and Laurentian granitoid rocks which are also exposed nearby. The U.S. Survey, which was responsible for mapping the southward extensions of the area covered by Lawson and Smit, took particular exception to Lawson’s interpretations. A special committee on stratigraphic nomenclature for the Lake Superior region was therefore convened by the U.S. Geological Survey and the Geological Survey of Canada and the resulting report was published in the Journal of Geology (Adams et al., 1905). It was critical of Lawson’s interpretation and suggested that there is evidence for the Coutchiching rocks to be younger than the Keewatin, a point that was later re-affirmed Minnesota by Van Hise and Leith (1909). Lawson was irate over the findings of the special committee and R.W. Brock, who was by then the director of the Geological Survey of Canada, invited Lawson to re-study the key parts of his original Rainy Lake map sheet in 1911. Lawson was also given the mandate to examine the rocks farther east along the Seine River toward Steeprock Lake and Sapawe. Several practical developments had ensued since the first mapping, including a gold rush to Mine Centre in the 1890’s, construction of the CNR south line through the area circa 1906 and major forest fires in the region in 1910, generating much new bedrock exposure. By then Lawson was in mid-career and had gained pre-eminence in many aspects of geological science in the western U.S. so that, when he produced his famous Geological Survey of Canada Memoir 40 in 1913 and an accompanying map in 1914, they were accepted without revision. In the memoir he reaffirmed his interpretation of the field relationships in the Rice Bay and Bear Passage areas where he observed the Coutchiching metasedimentary rocks to dip at moderate angles below Keewatin strata. He also issued a bitter challenge to the members of the special committee (Memoir 40, p.13-14): “The facts here recited in regard to this line of contact, particularly near the railway on the shores of Bear Passage and the south end of Redgut Bay, taken in connexion with the relations of the Coutchiching to the granite, appear to me to prove conclusively the superposition of the Keewatin upon the rocks mapped by me as Coutchiching in the report of 1887. I invite the attention of the International Committee and of the U.S. Geological Survey to this section and challenge them in view of the facts there Figure 7: Bad Vermilion Lake area - 88 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 apparent and easily accessible, to deny the relations of the Keewatin and Coutchiching as I mapped and described them a quarter of a century ago. The fact that these eminent authorities have denied in toto the existence of the Coutchiching series as a constituent member of the Archean below the Keewatin, without any attempt to verify the very explicit statement of the evidence in regard to this section contained in the report of 1887 places them in a curious light from the point of view of scientific method.” While forcefully retaining his contention that the Coutchiching rocks at Rice Bay (Fig. 4) and Bear’s Passage (Fig. 5) are positioned below the Keewatin, Lawson also admitted to an error in the Bad Vermilion Lake area (Fig. 7). There he proposed the new term “Seine Series” for the conglomeratic metasedimentary rocks that he had previously included as a basal part of the Keewatin. He now confidently placed the basal Seine conglomerate unconformably above both the Laurentian granitoid rocks and the Keewatin metavolcanic rocks in that area (Fig. 6b). He also noted the presence of trough crossbeds in the sandy portions of the Seine series near Old Mine Centre (Fig. 7) and used the newly recognized criterion of determining the directions of stratigraphic younging using their shapes. This allowed him to define a synclinal fold within the Seine sedimentary sequence in a narrow belt extending eastward along the Seine River (Fig. 2). He also recognized that the Seine Series locally extended farther eastward beyond the Rainy Lake area. In so doing, he mistakenly classified sedimentary rocks at Sapawe (Fig. 1, then known as Iron Spur) as part of the Seine Series. The granitoid Blalock stock cuts metasedimentary rocks discordantly at that locality so Lawson introduced the new term “Algoman” for such intrusions which he believed to be generally younger than the Seine (Fig. 6b). Although subsequent studies at Sapawe support Lawson’s contention of a late-tectonic intrusion, they also have consistently portrayed the intruded sedimentary rocks there as part of the Coutchiching rather than the Seine. Nonetheless, Lawson offered other acceptable field and petrographic distinctions that argue for the existence of a younger set of Algoman granitoid intrusions in the Rainy Lake area proper. They tend to contain higher proportions of K-feldspar than the dominantly sodic tonalitic rocks which comprise the Laurentian. He also mapped a narrow band of conglomerate near Hopkins Bay, west of Rice Bay (Fig. 2), and tentatively correlated it with the Seine sequence: at that locality he also presented strong evidence that the conglomerate is cut by younger Algoman granitoid rocks. As he had in the 1880’s Lawson used the International Geological Congress, this time at Ottawa in 1913, to promote his revised view of Rainy Lake geology and Precambrian stratigraphy in general. A debate was staged between Lawson and C.K. Leith to present arguments for and against the findings of the special committee: as later recalled by Leith, Lawson had a “slashing style” and “while I came out feeling I had presented the facts, I also felt Lawson had chewed me up and thrown me to the wolves” (Dott, 2001, p.1007). Lawson’s views were further solidified during the 1913 International Congress field trip that he led on Sunday, August 17th for approximately 90 participants who had traveled by C.N.R. to the Mine Centre and Bear’s Passage train stations after similar visits at Iron Spur and Steep Rock Lake the day before. At Mine Centre, participants were given the option of riding in horsedrawn wagons from the station to the Golden Star Mine along the Shoal Lake Road or taking a short boat ride across Bad Vermilion Lake to a walking trail leading to the mine (Fig. 7). At Bear’s Passage, one group was assigned to a boat trip which visited lakeshore outcrops along Redgut Bay and Bear’s Passage (Fig. 5) while others made a traverse though a similar geological section exposed relatively new rock cuts along the C.N.R. railway line. A carefully prepared itinerary and field guide for both of the historic localities (Uglow, 1913) allowed Lawson to illustrate the nature of each of his five stratigraphic units and his observations on the relationships among them. Lawson’s revised interpretation of the geology of the Lake of the Woods and Rainy Lake regions prevailed for another decade (Bruce, 1925) before the idea that there was still a “problem” was revived by F. F. Grout of the Minnesota Geological Survey. Grout (1925) reviewed the field relationships at the type locality of the Coutchiching near International Falls (Fig. 3) and at outcrops which Lawson had assigned to the Seine in the area of Neil Point farther to the east. Grout affirmed Lawson’s use of cross-bedding as an indicator of stratigraphic younging at Neil Point but offered an alternative overall interpretation which placed both the Seine and Coutchiching above the Keewatin. He then moved northeastward across the international boundary to a locality south of Bear’s Passage known as Morton Island (Fig. 5). There he used the newly recognized - 89 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 field criterion of graded bedding to deduce that the direction of stratigraphic younging in the Coutchiching is northward and away from the Keewatin volcanic rocks. He also visited the key localities at Rice Bay, Bear Passage, Shoal Lake and also at Jackfish Lake southwest of Steeprock Lake. In all cases he raised objections to Lawson’s positioning of the Coutchiching and placed it above both the Keewatin and the Seine (Fig. 6c). The problem expanded in scope when, during a subsequent field examination with T.L. Tanton of the Geological Survey of Canada, it became apparent that Grout had made a significant observational error on the Minnesota side of the boundary by misinterpreting an intrusion breccia to be a conglomerate of sedimentary origin. Tanton (1927) took great pains to publicly point this out at a Geological Society of America Precambrian Symposium, noting that the error was made by “a Minnesota geologist”. Grout, in a discussion of Tanton’s paper, duly acknowledged his own mistake but also stated combatively that a “structure section sketched in the field by Tanton shows more errors than any before”. Rather than resolving the problem, these exchanges only served to accentuate it. Some years later, Tanton (1936) made a comparable error by misinterpreting the Seine conglomerate at Shoal Lake to have been intruded by the Laurentian granitoid rocks rather than being deposited above it (Fig. 6d). Apart from his local mistake, Grout’s overall arguments found some traction and provided the impetus for additional field work. J.E. Hawley, a graduate of the University of Wisconsin and a professor at Queen’s University, was well versed in stratigraphy and structural geology. Along with a review of the Shoal Lake area, he conducted a study of the Seine and Coutchiching eastward though Jackfish Lake and past Sapawe. He concluded (Hawley, 1930) that part of the problem was, in some localities at least, that the contacts between the Coutchiching and Keewatin are arguably occupied by faults so that attitudes of strata alone provide inconclusive evidence of stratigraphic order. F.F. Grout also remained influential at that time and recommended the Seine-Coutchiching Problem to P.L. Merritt who conducted a study of the entire corridor from Rainy Lake eastward along the Seine River watershed for his Ph.D. thesis at Columbia University (Merritt, 1934). His conclusions concerning the two metasedimentary sequences supported Grout’s interpretation (Fig. 6c) and he suggested that, with the notable exception the clastic rocks at Rice Bay and Bear’s Passage, the term Coutchiching should be abandoned altogether and that all other sedimentary units should be included in the post-Keewatin, Seine Series above the basal conglomerate. Like Hawley, Merritt also provided detailed documentation of a fault contact between the Keewatin and sedimentary units at various localities and traced a continuous fault from Calm Lake eastward through Sapawe as far as Dog Lake, 60 km north of Thunder Bay: this is known today as the Quetico Fault. He also proposed (Merritt, 1934, p. 371) that “the fault movement along the contact is believed to combine a horizontal shear with an associated overthrust to the south”. Grout had a further influence on the expanding Seine-Coutchiching problem in that he inspired Francis Pettijohn, his field assistant during the work at Rainy Lake, to take on pioneering work in the study of Archean sedimentary rocks in general. Pettijohn did his undergraduate and graduate work at the University of Minnesota and, in accepting the Penrose Medal for 1975 from the Geological Society of America, he acknowledged the importance of Grout’s tutelage as well as the short time that he spent studying with A.C. Lawson at Berkley in 1927-28 to learn more about the alternative view. Pettijohn’s Ph. D. thesis documented the Abram Lake conglomerate in the Minnitaki Lake area in part because it resembled both the Seine conglomerate at Rainy Lake and the Ogishke conglomerate at Knife Lake Minnesota (Fig. 1). He later summarized his findings at all three of these localities as well as at several others in the northern Lake Superior region (Pettijohn, 1937) to also conclude that the majority of sedimentary units are arguably younger than the Keewatin. He also raised the possibility, however, that not all of the units included in the Keewatin need be of the same age and that local intercalation between volcanic and sedimentary rocks may locally be possible. As important as these insights ultimately proved to be, Pettijohn’s resolution of the Seine-Coutchiching problem also called for the abandonment of both of Lawson’s local units (Seine and Coutchiching) in favour of an overarching “Knife Lake Series” composed of similar rocks which had precedence of definition in the geological literature in Minnesota. This also reinforced Grout’s views and a summary paper on the topic (Grout et al., 1951) notably included a section entitled “No Coutchiching Recognized in Minnesota”. Nonetheless, the “SeineCoutchiching problem” was kept alive intermittently well into the 1970’s even to the extreme point of academic speculations that no unconformities existed - 90 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 at all and that there was simply a proximal to distal lateral facies equivalence (Fig. 6e) among broadly age-equivalent Keewatin, Seine and Coutchiching rocks (Bass, 1961; Ayres, 1971; Mackasey et al., 1974; Goodwin, 1977). Sam Goldich who was a graduate of the University of Minnesota rejoined that institution in 1948 as a professor and director of the Rock Analysis Laboratory where he and Alfred Nier gained international reputations as pioneers in isotope geochemistry and geochronology. An outcome of that work was the application of geochronological methods to the resolution of stratigraphic problems in the Lake Superior region (Goldich et al., 1961; Goldich, 1968). Goldich compromised on the question of the SeineCoutchiching problem by favouring the term “Knife Lake Group” over “Seine Group” above the Keewatin but also allowed for the possibility (using a question mark for emphasis) of the existence of Coutchiching metasedimentary rocks below it. Goldich tackled the geology of the Rainy Lake area head on by supporting three field-based M.S. theses at the University of Minnesota (Alt, 1959; Frye, 1959; Peterman, 1959) and the resulting maps and samples became the basis for on-going geochronology and geochemical studies (Peterman et al, 1972; Goldich and Peterman, 1980). With time, Lawson’s original terminology and interpretation of stratigraphic order was largely supported by the data but with the added implication that all of the constituent rock-forming events took place in less than 100 million years with only local evidence for younger post-metamorphic retrogression. At the time of the studies by Goldich and his colleagues an important fact remained: apart from Grout’s work in Minnesota, no geologist other than A.C. Lawson had mapped systematically in the Rainy Lake area. This had been undertaken by him at a scale of one inch to four miles in 1885-87 and, with the assistance of H.C. Cooke and R.C. Wallace, at one inch to one mile in 1911. New mapping in greater detail was therefore ultimately undertaken by the Ontario Division of Mines beginning in the 1970’s (Davies, 1973; Blackburn, 1973; Harris, 1974; Wood et al., 1980 a, b; Fumerton, 1985). The outcrop mapping of Fred Harris is perhaps the most notable because it provided an advanced level of lithostratigraphic detail, at a scale of one inch to ½ mile, while covering the historically controversial Rice Bay and Bear’s Passage areas. He also provided new local evidence for stratigraphic younging in the Keewatin strata including the first recorded use of the shapes to pillows in basaltic flows in this area. Harris (1974) avoided the use of the historical stratigraphic terms but his table of formations tends to support Lawson’s original interpretation of metasedimentary biotite schists at the base of the sequence. John Wood provided a comparable level of mapping at Mine Centre (Wood et al., 1980 a, b) with a focus on the Seine and Coutchiching metasedimentary rocks (Wood, 1980). Companion studies of the geology in the Minnesota portion of the Rainy Lake area were conducted under the auspices of the Minnesota Geological Survey and the US Geological Survey (Ojakangas, 1972; Southwick, 1972; Southwick and Ojakangas, 1979; Southwick and Sims, 1980). Poulsen (1980) made extensive use of the report and maps of Harris (1974) as a foundation for structural and metamorphic studies in the Rice Bay and Bear’s Passage areas. It eventually became clear, however, that one of the flaws in Lawson’s original interpretation was that it relied on the assumption that structural superposition of the Keewatin above the Coutchiching equates to stratigraphic superposition as well in rock packages that are arguably overturned (Poulsen et al., 1981). This led to a revised interpretation of stratigraphic order (Fig. 6f) but one without geochronological constraint. The full essence of the Seine-Coutchiching problem was ultimately clarified by application progressively improved methods of U-Pb analysis of zircons (Davis, 2023). Strategic sampling of each of Lawson’s five lithostratigraphic units across several sites where field relationships had been established (Davis et al., 1989; Davis et al., 1990; Fralick and Davis,1999) provided the results that form the basis of the current chronostratigraphic chart for the area (Fig. 6f). Keewatin metavolcanic rocks and Laurentian metaplutonic rocks were shown to be of similar age (circa 2727 Ma) whereas detrital zircons from the Coutchiching suggested a younger age (circa 2700 Ma) and a granitoid clast and detrital zircons from the Seine conglomerate even younger (<2693 Ma). The age of crystallization of the Algoman intrusions was estimated to be in the range of 2693 to 2684 Ma. In total, the geochronological constraints have shown that most of the historical interpretations, including those of Lawson, had both merits as well as flaws whereas the lateral facies concepts which were so widely and uncritically accepted in the 1970’s have proven to be entirely untenable. The net result, however, is that - 91 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Lawson’s placement of the Coutchiching beneath the Keewatin on the grounds of the dip of strata alone was the main source of geological error. It was not that he did not understand the difference because, in Memoir 40, he appears to have been the first geologist to have compare directions of dip to the directions of younging (way-up or bedding top) in cross-bedded arenite of the Seine sedimentary unit. Lawson (1913) did acknowledge that he had learned about the utility of truncated cross-bedding from his field assistant J.D. Trueman, then a graduate student who in turn had been taught this by W.O. Hotchkiss at the University of Wisconsin (Dott, 2001). Hotchkiss was also familiar with upward-fining grain size variation in sandstone mudstone sequences but this was not yet in common use and therefore the significance of graded bedding, as preserved at Bear Passage area, was not yet appreciated by Lawson in 1913. It took the work of F.F. Grout (1925) to demonstrate that the graded beds at Morton Island indicate that the Coutchiching beds there stratigraphically overlie the Keewatin. Lawson also certainly would have been aware of the stratigraphic use of pillowed volcanic flows, as advocated by Morley E. Wilson (1913) in Memoir 39 of the Geological Survey of Canada, but was of the opinion that this method was unsound because he believed that pillows, then referred to as ellipsoidal structures, were of intrusive origin (Lawson, 1912). As one looks back, the Timiskaming-Keewatin problem evolved along similar paths as another great geological debate that played out during much the same time frame, the Highlands controversy of Scotland. That problem also involved many observers who were focussed on small, geographically separated parts of a bigger problem and it has been said that, in many cases, they did not know what they did not know (Oldroyd, 1990). A case in point is the famous anecdote concerning T.L. Tanton of the Geological Survey of Canada and E.B. Bailey of the British Geological Survey (Dott, 2001). Tanton, who had graduated from the University of Wisconsin in 1915 under the supervision of C.K. Leith, led a group of Princeton geologists on a tour of Rainy Lake as part of their geological trip across Canada by rail in 1927. The group included two eminent guests from overseas, L.W. Collett from Switzerland and E.B. Bailey of Britain (Bailey, 1927). Tanton demonstrated the utility of cross-bedding and graded bedding to determine wayup in metasedimentary rocks, using Lawson’s examples from the Seine Group at Shoal Lake and Grout’s Coutchiching outcrops at Morton Island respectively. This resulted in Tanton’s inclusion as a participant on a reciprocal visit to Scotland where he convinced Bailey that the Dalradian strata at Ballachulish are overturned (Tanton, 1930; Bailley, 1930, Dott, 2001). Another point of communality between the two controversies is that the reputations of the observers, especially Sir R.I. Murchison in the Highlands and A.C. Lawson at Rainy Lake, tended to get in the way of the geological facts. This should not overshadow the reality, however, that in his first, youthful burst of mapping from 1882 to 1889 and in his mid-career re-study from 1911 to1913, Lawson identified the five lithological building blocks which are representative of the architecture of virtually every Archean greenstone belt in the world. As Oldroyd (1990) has pointed out for the Scottish Highlands controversy, it is not only about who was right and who was wrong but it is also about the process of narrowing in on a consensus view based on the facts at hand. Similar sentiments were expressed by Lawson himself in the introduction to his 1913 report which fuelled the Seine-Coutchiching problem in the first place. The overall lesson of the problem seems to be that: “Science is never ‘settled’ but evolves by the accumulation of facts, new ideas and vigorous open discussion and debate. Consensus is irrelevant in science; only truth matters.” (Dewey and Ryan, 2022, p.1834). Rainy Lake Wrench Zone Poulsen (1986b) introduced the term “Rainy Lake wrench zone” to distinguish rocks between the E-W Quetico Fault and the ENE Rainy Lake – Seine River Fault from the Quetico metasedimentary belt to the south and the main mass of the Wabigoon granite-greenstone belt to the north (Fig. 8). The rationale for highlighting the wrench zone involved many different geological aspects (Poulsen, 1986b) but the most prominent are the distinctive lenticular. s-shaped lithostratigraphic domains which merge with the discordant boundary faults. Broadly similar patterns are also evident in the steep metamorphic foliation which affects the Seine as well all of the older lithostratigraphic units. This is also the area in which the Seine – Coutchiching problem mainly played out and where generations of geologists contributed to the understanding of diverse aspects of its geology. It is also the focus of this field guide which can be used to illustrate the major lithostratigraphic - 92 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 8: Simplified geological map of the Rainy Lake Wrench Zone. units that comprise the wrench zone as well as the related topics of deformation, metamorphism and metallogeny. Keewatin Lawson applied the term “Keewatin Series” to all of the Archean metavolcanic rocks in the Rainy Lake area mainly to distinguish them from foliated quartzo-feldspathic rocks of probable plutonic origin. He initially did this in a descriptive way (Lawson, 1885) but his Rainy Lake reports (Lawson, 1887; Lawson, 1913) also provided petrographic detail and genetic interpretation. The Keewatin rocks within the wrench zone include lithofacies which are common to Archean greenstone belts in general. Mafic volcanic rocks predominate in the northwestern part of the zone, particularly at Windy Point, Nickel Lake and Pocket Pond. The rocks at these locations were metamorphosed to amphibolite facies assemblages so that primary features are difficult to document in the resulting foliated mafic tectonites. In places where strain is moderate it is relatively easy to identify pillows and varioles but the level of distortion in many places (Fig. 10a) makes it difficult to confidently use the shapes of pillow to confidently define directions of younging (Borradaile and Poulsen, 1981). A notable exception is at Pocket Pond (Fig. 9a) where adequate evidence of stratigraphic polarity is preserved (Fig. 10b). Felsic metavolcanic rocks predominate in the southeastern part of the wrench zone where they are commonly intercalated with rocks of andesitic composition (Fig.10c), The rhyolitic rocks are commonly quartzphyric and included both coherent (Fig. 10d) and volcaniclastic (Fig. 10e) facies. Figure 9: Pocket Pond locality - 93 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B v C D E F Figure 10: a) westward plunging shape lineation defined by deformed pillows in metabasalt, Nickel Lake area; a) Pillow basalt, Pocket Pond; c) Amygdaloidal basalt, Port Arthur Copper; d) spherulitic rhyolite, Ottertail east; e) Rhyolite Breccia, Wind Bay; f) volcaniclastic ferropicrite, Belacoma area. One outstanding unit within the Keewatin sequence is composed of a distinctive ultramafic volcaniclastic rock (Fig. 10f) which is exposed in the Grassy Portage Bay area (Fig. 4). The unit was first recognized by Harris (1974) who classified it as an intermediate volcanic rock, mainly because of its common bright green, chloritic appearance along with volcaniclastic textures. Poulsen (1980) prosaically termed it “magnetic green rock” which is composed mainly of Mg-chlorite plus actinolite and magnetite. He provided lithogeochemical analyses to show that the rock has an ultramafic bulk composition but incorrectly classified it as a komatiite, a rock type with which it shares only some chemical similarities. He also compared the unit, both chemically and texturally to the betterknown picritic Steep Rock Ashrock approximately 100 km to the east and suggested that their separation might be due to dextral displacement on the Quetico Fault (Fig. 1). Steve Schaefer conducted a study of the ultramafic units at both localities and confirmed their volcanic origins (Schaefer and Morton, 1991). He also provided the acronym GUP (Grassy Portage - 94 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Ultramafic Pyroclastic) for the rocks at the Rainy Lake locality. Goldstein and Francis (2008) pointed out the differences in the chemical composition of this unit compared to komatiites: the GUP shows higher FeO, TiO2 and incompatible elements (e.g., Nb) as well as displaying fractionated rather than flat rare earth element patterns. Goldstein and Francis (2008) reclassified the rocks as pyroclastic ferropicrites, noting that they are examples of relatively rare Ferich volcanic varieties that were likely derived from partial melting a mantle source that was enriched in Ti and rare earth elements. A further characteristic of the GUP is that it contains microdiamonds which were discovered in 2008 by MetalCORP Limited at the Beaver Pond Occurrence (Hinz et al., 2010). All of these observations have significantly improved the understanding of this unusual volcanic unit but questions remain regarding its stratigraphic position and regional significance. Despite the remarkable similarity to the Dismal Ashrock at Steeprock, the notion of a strike-slip separation of the same unit is still feasible but not fully demonstrated. Tomlinson et al., (2003) reported a maximum age of 2780.4 +/-1.4 Ma for the Dismal Ashrock based on analyses of inherited zircons and argued that it is feasible for it and overlying basalts (Witch Bay formation) to be as young as other sequences in the Western Wabigoon Subprovince: by extension, this would include the mafic-ultramafic volcanic units in the Grassy Portage Bay area. If the ages of the ultramafic volcanic rocks at the two distant localities prove to be different, however, it would mean that an alternative explanation for their similarity would have to involve operation of similar processes at different times. In that case the communality might be sought in the mantle composition and depth that led to the formation and deposition of these unusual rocks. Interflow metasedimentary rocks comprise a common but volumetrically small component of the Keewatin sequence. Although in places these rocks could be mistaken as providing evidence for interdigitation with Coutchiching biotite schists or with volcaniclastic rocks of intermediate composition, in most cases, they are arguably metalliferous, synvolcanic sedimentary units which range from pyritic mudstone and minor sandstone, to chert-magnetite banded iron-formation (Fig. 11a) and pyritic massive sulfide deposits (also termed sulfide facies ironformation). The sulfide-bearing varieties were targets for possible sulfur production in the period around World War I when, particularly at Nickel Lake, they were noted to contain anomalous concentrations of CoNi-Zn-Cu. In places zinc is also a locally anomalous component and, at Pocket Pond, the small sphalerite lenses discovered in the 1970’s are associated with iron-formation intercalated with metabasalt (Fig. 9). From a strictly geological perspective the presence of laterally extensive interflow units proves valuable for establishing a sense of stratification within the Keewatin because they not only can be mapped discontinuously in outcrop and drill core but cane be easily traced accurately by magnetic and electromagnetic surveys. A.C. Lawson’s 1914 geological map of Rainy Lake also includes two mafic plutonic rock types which he regarded to be part of the Keewatin sequence: extensive units of what he termed hornblende gabbro in the Grassy Portage Bay area (Fig. 4) and anorthosite in the Bad Vermilion Lake area (Fig. 5). Subsequent mapping has shown that he underestimated the total volumes of mafic plutonic rock in both cases and this was with good reason. It is now well-understood that thick, mafic submarine lava flows are capable of slow cooling rates to produce what can easily be accepted as a “gabbro-textured” facies that grades vertically and laterally over short distances into finer grained basaltic rocks, making their visual distinction from plutonic equivalents difficult. Furthermore, where amphibolite facies metamorphism has affected mafic volcanic rocks, recrystallization tends to coarsen the texture and obscure primary features: this is certainly the case in the northwestern western part of the Rainy Lake Wrench Zone. Finally, considerable local variations in textural detail are common in layered mafic intrusions (Fig. 11b, c, d) that that are difficult to map at a reconnaissance scale. What Lawson did map, however, were two of most extensive, distinctive and homogeneous plutonic phases, leucogabbro in the Grassy Portage Intrusion (Fig. 11e) and coarse anorthosite in the Bad Vermilion intrusion (Fig. 11 f). Detailed mapping by Hodgson (1959) at Grassy Portage Bay and by Harris (1974) at both localities provided much better definition of the full extents of these intrusions. Ashwal et al. (1983) undertook a more advanced petrological and geochemical study of the Bad Vermilion anorthosite and concluded that it represents the remnants of a subvolcanic magma chamber from which aliquots of magma had been extracted as extrusive lava flows. Poulsen and Hodgson (1985) reviewed the disposition of the different phases of both intrusions and the sulfide - 95 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B D C D F E Figure 11: a) chert-magnetite iron-formation, Pocket Pond; b) thin-layered gabbro, Grassy Portage intrusion, west side of Redgut Bay; c) thick-layered gabbro-melagabbro, Northrock East trenches, Grassy Portage intrusion; d), Pegmatitic Gabbro, Northrock E trenches, Grassy Portage intrusion; e) leucogabbro, Grassy Portage intrusion; f) coarse anorthosite, Bad Vermilion intrusion, Scott Islands (the edge of the compass in the bottom left measures 10 cm) and oxide mineralization within them, providing support to the idea that they are examples of synvolcanic layered intrusions resulting from cumulus growth and magma fractionation. Both intrusions also received attention for their economic potential during exploration programs for Cu-Ni-PGE sulfide and Ti-V oxide mineralization (Hinz et al., 2010). The Bad Vermilion Intrusive complex and the surrounding metavolcanic rocks have recently been described as an arc-related “ophiolite” sequence (Wu et al., 2016) but this is highly unlikely given the dominance of rhyolite in the volcanic section and the absence of both peridotite and sheeted dikes. The ages of the Keewatin units were largely unknown until the mid-1970’s despite many attempts to apply modern geochronological methods (Goldich, 1968; Tilton and Grunenfelder, 1968; Hart and Davis, 1969; Peterman et al., 1972). At that point improvement in analytical precision and accuracy allowed U-Pb geochronology on carefully constrained samples to impact stratigraphic interpretations (Davis, 2023). Davis et al. (1988) applied these methods in the Rainy Lake Wrench zone to show that the units which were historically classified as Keewatin formed around 2727 - 96 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Ma in a remarkably short interval of five to six million years (Fig. 5f). This included direct analysis of rhyolitic rocks from both the northwestern and southeastern part of the zone as well as the indirect constraint of mafic (Grassy Portage Gabbro) and felsic (Mud Lake trondhjemite) that cut the volcanic rocks. More recent attempts to provide additional ages of volcanic rocks near the Bad Vermilion Intrusion have proven to be unsuccessful in light of the lower analytical precision and accuracy of the methods employed (Wu et al. 2016). Coutchiching Lawson’s 1914 map of Rainy Lake outlines three areas of Coutchiching rocks labeled as “mica schist, paragneiss and phyllite”. The most extensive area occurs south of the Seine River Fault in Quetico Subprovince where the term Quetico metasedimentary rocks also applies (Fig. 12a). The other two major localities are located within the Rainy Lake Wrench Zone: a southern belt extending from Fort FrancesInternational Falls northeastward along Swell Bay and a northern one as a partially annular zone within the Rice Bay Dome (Figs. 2, 3, 4). Grout (1925) A B C D E F Figure 12: a) Quetico metasedimentary rocks, Bleak Bay area; b) thick-bedded wacke, Sandpoint Island c) graded beds cut by ENE cleavage, Morton Island (N to top of photo); d) knotty biotite schist containing retrograded staurolite and garnet, Great River Road; e) graded beds, Bear’s Passage boat launch; f) graded beds in greenschist facies turbidites, Old Station Road (diagonal lines are glacial striae). - 97 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 who was the first to recognize graded bedding in the metasedimentary rocks in the Swell Bay belt (Fig. 12b, c) and to apply it to establish local stratigraphic polarity at Morton Island (Fig. 13). This was confirmed by Merritt (1934) who also notably interpreted the colour banding of graded rocks in the Swell Bay as “varves”. R.W. Ojakangas who often lamented that the Canadian glaciers had been cruel to Minnesota re-examined the sparse exposures of the Coutchiching rocks at Ranier, Minnesota near Lawson’s type locality (Fig. 3). He described the rocks there as metagreywacke noting that they originally consisted of alternating beds of greywacke sandstone (or simply wacke) and mudstone deposited, not by glacial processes but by turbidity currents on submarine fans (Ojakangas, 1972; 1982). Most authors who have studied the belt of Coutchiching rocks along Swell Bay have also noted that they been clearly intruded by younger granitoid rocks (Algoman) and that the rocks on the northern shore of Swell Bay display amphibolite facies, pelitic metamorphic assemblages (Fig. 12d) involving biotite, muscovite, garnet, cordierite and staurolite (Ojakangas, 1982; Poulsen, 1980). The higher metamorphic grade has also been implicated by many authors for obscuring primary features such as graded bedding in the metasedimentary rocks. The most contentious interpretations of the stratigraphic significance the Coutchiching rocks in the Swell Bay corridor result from observations in the Bear’s Passage area (Figs. 4, 14). The Keewatin at this locality consists of a northwestward-dipping section composed of the upper part of the southeastwardyounging Grassy Portage layered intrusion overlain by a thin unit of what are arguably mafic metavolcanic Figure 13: Morton Island locality (adapted from Poulsen and Wood, 1982) rocks. The staurolite-bearing metasedimentary rocks, although locally folded, also dip to the northwest and are cut discordantly by granodiorite of the Bear’s Passage intrusion (Fig. 4). Although minor reversals in polarity of grading suggest local folding within the Coutchiching rocks in the Bear Passage area, a good quality exposure at their contact with Keewatin strata (Fig. 12e) demonstrates that the metasedimentary rocks are overturned (Poulsen, 1980). This plus the observations at Pocket Pond (Fig. 9) and Morton Island (Fig. 13), provides the geological evidence in favour of the Coutchiching being younger than the Keewatin. The most conclusive evidence, however, ultimately came from U-Pb analyses of detrital zircon in biotite schist near Tunnel Bay and in well preserved greenschist grade metagreywacke (Fig. 12f) northeast of Shelter Cove (Fig. 6) which represents the northeastward extension of the exposures at Morton Island (Davis et al. 1989). The age of the Coutchiching is constrained by the youngest detrital zircon grains at approximately 2704 Ma and by the circa 2692 Ma age of across-cutting felsic dike (Fig. 5 f). The presence of much older detrital grains (2930, 2940 and 3060 Ma) also suggested a potential contribution of detritus to the Coutchiching from a source area comparable to the Marmion domain north of the Quetico Fault extending in the Steeprock Lake area (Fig. 1). Similar conclusions were reached for the Quetico metasedimentary rocks by Davis et al. (1990). Laurentian Lawson (1887) used the term Laurentian for variably foliated granitoid rocks in general but by 1913 he only applied it at only three localities, Bad Vermilion lake, Figure 14: Bear’s Passage locality - 98 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Rice Bay and Grassy Island near Neil Point (Fig. 2). The Laurentian granitoid rocks at Bad Vermilion Lake occupy three sinuous bodies that are broadly co-spatial with the Bad Vermillion layered intrusion (Fig. 7). The sodic granitoid rocks range from tonalite (Fig. 12a, b) to trondhjemite (Fig. 12c) in composition (Goldich and Peterman, 1980) and likely occupy the remnants of sills that are broadly concordant with stratigraphic layering in the surrounding northward-younging Keewatin volcanic rocks (Fig. 7). It is noteworthy that Lawson (1887) was the first to suggest that they might be syn-volcanic, subvolcanic intrusions. This point was verified by Davis et al. (1989) who established nearly identical ages of 2728 Ma for the intrusive Mud Lake trondhjemite near the Stellar gold deposit and an overlying rhyolite west of the Port Arthur copper deposit. The Laurentian rocks at Grassy Island likely represent an isolated remnant of the same stratigraphic section to the southwest (Fig. 2). A noteworthy characteristic of some outcrops of tonalite, particularly near gold-bearing quartz veins, is a quartz-rich sericitic rock (Fig. 12b) that was termed “protogene” by the early gold explorers in the region and results from plagioclase-destructive metamomatism related to carbonatization associated with brittle-ductile shear zones in the tonalite (Diamond and Marshall, 1990). The Laurentian rocks exposed in the core of the Rice Bay Dome (Fig. 4) are much more difficult to interpret, in part due to overprinting deformation and amphibolite facies metamorphism. Lawson’s 1914 map classified them to include as an inner body of granite and granite gneiss with an intrusive relationship with an outer annulus of Coutchiching biotite schist. Subsequent petrographic studies documented the distinctions among the lithologies (Frye, 1959; Peterman, 1959) and the term “paragneiss” was ultimately given to the innermost rocks. The existence of a large pluton was questioned and both the paragneiss and biotite schist were considered to be different components of the Coutchiching (Peterman, 1959; Peterman et al. 1972). By the same token, however, a small volume of deformed quartz-feldspar dikes and sills were shown to cut the paragneiss within the dome (Peterman et al. 1972). Harris (1974) took much the same approach and, apart from areas where the minor granitoid dikes and sills were particularly abundant, he mapped most of the interior of the Rice Bay Dome as being composed mainly of “biotite-feldspar-quartz schist” which he also assigned to the lower metasedimentary unit (i.e. the Coutchiching). Goldich and Peterman (1980) continued to view the rocks in the interior of the Rice Bay Dome as being composed of paragneiss derived from epiclastic sedimentary rocks but they also presented chemical data to show that they are different from the Coutchiching biotite schists and metagreywackes. Poulsen (1980) used the non-genetic term “grey gneiss” for rocks in the interior of the Rice Bay Dome (Fig. 15d, e) and also showed that they are fundamentally different in chemical composition from the annulus of biotite schist that envelopes them (Fig. 4). The minor deformed quartz-feldspar porphyry dikes (Fig. 15 e, f) are in, turn, different in chemical composition from both the grey gneiss and biotite schists (Poulsen. 1980; Goldich and Peterman, 1980). Dick Ojakangas (personal communication, circa 1980) provided the novel suggestion that some of the grey gneisses actually may have been felsic volcanic rocks rather than felsic intrusions. This prompted Poulsen (1984) to opt for the uninspiring descriptive term quartzo-feldspathic gneiss to distinguish the Laurentian rocks from the Coutchiching biotite schists. Davis et al., (1989) reported a U-Pb zircon age of 2725+/-2 Ma from a sample of the quartzofeldspathic gneiss near Moran’s Bay (Fig. 4) to demonstrate its probable chronological equivalence with both the Keewatin rhyolite and the Laurentian Mud Lake trondhjemite in the Bad Vermilion Lake area. One of the notable lithogeochemical attributes of the biotite-rich Laurentian gneisses within the Rice Bay dome is their local deficiency in Na and Ca and their excess in Mg and Fe relative to their high silica and low Ti contents (Goldich and Peterman, 1980; Poulsen, 1980). One explanation for this is that they were locally subjected to plagioclase-destructive metasomatism which would also explain the presence of staurolite, andalusite and/or cordierite within them at specific sites. Such alteration in well-known in the environments of volcanic-associated massive sulfide deposits. Beakhouse (1984) evaluated this possibility in the western part of the Rice Bay dome where he identified the metamorphic assemblage quartzchlorite-garnet-anthophyllite-staurolite with possible large relict grains of cordierite at one locality and common garnet over a larger area. Teck Corporation subsequently verified these mineralogical anomalies with further mapping and lithogeochemical surveys to conclude that the alteration is likely related to pyritic massive sulfide mineralization within an iron- - 99 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B C D E F Figure 15: a) Bad Vermilion tonalite, Mine Centre; b) Sericitized tonalite (“protogene”), Mine Centre c) Mud Lake trondhjemite, Stellar gold property; d) grey quartzo-feldspathic gneiss cut by leucocratic dikes, Rice Bay, e) quartz-phyric grey gneiss cut by quartz-feldspar-phyric dike, Laurentian gneiss unit, Moran’s Bay; f) deformed quartz (dark) and feldspar phenocrysts in qfp dike, Moran’s Bay formation unit near the outer part of the Rice Bay dome (Alderman, 1988). In summary, despite incremental advances in establishing the geological facts concerning the Laurentian gneiss of the Rice Bay dome, considerable uncertainty remains about its origin. It has been established to be age equivalent and compositionally similar to both the Keewatin and Laurentian rocks in the Bad Vermilion Lake area but much study is required to establish its stratigraphic significance with respect to the Coutchiching and Keewatin rocks which structurally overlie them. The weights of evidence suggest, however, that the definitively intrusive aspects of the dome are attributable to the minor volume dikes and sills for no absolute ages have been established. On lithogeochemical grounds they may represent a phase on the younger Algoman intrusive suite (Goldich and Peterman, 1980). - 100 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Seine Of all of Lawson’s many achievements at Rainy Lake, it was arguably the recognition of the sedimentary rocks of the Seine Series, the interpretation of their probable depositional paleoenvironment and the demonstration of a high-angle unconformity beneath them that have best withstood the test of time. Although the overall level of exposure is uneven, the critical localities where this is best illustrated are located between Shoal Lake and Bad Vermilion Lake in the Mine Centre area (Fig. 7). In particular, exposures of the basal conglomerate (which Lawson termed “fanglomerate”) near the Golden Star Mine (Fig. 16) and the overlying arenite facies exposed on islands in Shoal Lake to the south provided the diagnostic evidence for Lawson’s arguments. Figure 16: Simplified geology of the Golden Star locality. Rocks of the Seine series occupy the area to the southeast of the trace of the unconformity and the underlying rocks of the Laurentian and Keewatin are located to the northwest. The S-shaped configuration of the unconformity trace is likely meaningful, not only because it mimics larger patterns in the wrench zone as a whole (Fig. 8) but also because the northsouth segment reflects lower than average intensity of superimposed strain. Lawson was the first to note that this is in part responsible for the convincing preservation of contact relationships. The basal Seine conglomerate dips shallowly southeastward whereas Lawson showed that an interflow chert-carbonate unit within the Keewatin dips moderately northward. A relatively minor refinement (Pouslen and Wood, 1982) is that pillowed metabasalt overlies the chertcarbonate marker and indicates a northwestwardyounging for the Keewatin rocks. In other words, there is evidence for back-to-back younging across a highangle unconformity. Although weakly aligned due to overprinting strain, a critical point of observation is that clasts in the basal conglomerate show no evidence of a prior metamorphic foliation (Fig. 17a). The derivation of the coarse gritty matrix of the basal conglomerate from the underlying Laurentian tonalite is also clearly evident when compared to the intrusive rocks below the nonconformity. The shallow dipping basal conglomerate (Fig. 17b) to which Lawson ascribed an alluvial origin has been mapped along a persistent ridge of fair outcrop (Fig. 16) but topographically recessive arenite which overlies it to the east is poorly exposed. The Seine arenite unit is well-exposed at Shoal Lake where cross-bedded sandstone (Fig. 17c) provides stratigraphic polarity as well as supporting the common interpretation of a fluviatile origin. Cross-bedded sandstone (Fig. 17d) also can be traced farther eastward along the Seine River (Fig. 2) where it can be demonstrated to be overlain by an upper unit of coarse, polymictic conglomerate (Fig. 17e) and, in some cases, intercalated with it (Fig. 17f). The uppermost conglomerate unit is notable for an abundance of granitoid clasts and Davis et al. (1989) reported an age of 2696.1+5/-3 demonstrating that it was sourced in a granitoid body that was much younger than the Laurentian which provided detritus for the basal Seine Conglomerate. Davis (1990) further constrained the depositional age of the sandsized fraction from arenite at Horsecollar Junction (Fig. 2) by noting the presence of abundant detrital zircons with a U-Pb age of approximately 2693 Ma., effectively the same age as the Bear Pass pluton. This fact contradicted Lawson’s original contention that all of the Algoman intrusions could be defined on the basis of the fact that they are younger than the Seine (see below). Nonetheless, Lawson’s original interpretation of the Seine Series mainly as a product of Archean alluvial and fluvial sedimentary processes has been reinforced and elaborated upon by several authors (Ojakangas, 1972; Wood, 1980; Fralick and Davis, 1999; Czech and Fralick, 2002). Although his language was somewhat dense, the overall message of Lawson’s paleoenvironmental interpretation is paraphrased as follows: “it seems a fair inference that the conglomerate represents a gravelly flood plain… The distribution of the conglomerate … indicates the course of a river (following) the dominant structural lines … at a time which antedates the intense complication which folded - 101 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B C D E F Figure 17: a) basal Seine conglomerate inter-clast quartz grit derived from underlying tonalite, Golden Star arear; b) stratified basal conglomerate, Golden Star area; c) trough cross-bedded Seine arenite in plan view, Shoal Lake showing younging toward the top of the photo; d) deformed cross-bedded Seine arenite and pebble conglomerate in cross-section view, Seine River Bridge; e) deformed polymictic conglomerate in cross section view, east of Mine Centre; f) sandstone interbed in coarse upper Seine conglomerate in plan view west of Wild Potato Lake. Note the angle between bedding (arrows) and foliation. and deformed the conglomerate” (Lawson, 1913, p.62). In other words, he envisioned the location of Seine conglomerate and arenite to have been controlled by syn-sedimentary faults to account in part for it’s elongate map pattern (Fig. 2). Algoman Lawson’s 1914 map portrays five different varieties of intrusive rocks at Rainy Lake in decreasing order of perceived age which he classified with the term Algoman: basic facies of syenite, syenite gneiss, granite and granite gneiss, banded and streaked gneiss and porphyroid gneiss. Harris (1974) made similar distinctions which allowed the least deformed Algoman rocks to be discussed in terms of three distinct spatial and compositional suites: the Rocky Islet Bay complex, the Swell Bay intrusions and the large and conspicuous Ottertail Lake Intrusion (Fig. 3). The first of these are dominated by quartz monzonite syenite and mafic syenite and are commonly feldspar-phyric (Fig. 18a, - 102 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B C D E F Figure 18: a) feldspar-phyric quartz monzonite, Raspberry Island; b) porphyritic quartz monzonite, Rocky Islet Bay; c) granodiorite cut by vertical sheeted quatz-pyrite veins, Bear’s Passage; d) xenolithic monzodiorite, Ottertail Lake intrusion; e) Intrusion breccia with granitoid matrix, western Ottertail Lake intrusion; f) incipient brecciation and granitoid infilling of metamorphic tectonite, Ottertail Lake intrusion. b), The Swell Bay intrusions, exemplified by the Bear Pass Pluton (Fig. 18c) are composed mainly of quartz monzonite and granodiorite (Goldich and Peterman; 1980). Some of these intrusions are compositionally zoned with mafic to intermediate margins and felsic interiors (Cram, 1923; Harris, 1974). The Ottertail Lake intrusion is also compositionally zoned from marginal hornblende-biotite quartz monzonite to interior leucocratic quartz monzonite in the interior (Goldich and Peterman, 1980): wallrock xenoliths are common in the marginal phase (Fig. 18d) and internal magmatic breccias (Fig. 18e, f) are well developed in what Lawson interpreted to be roof pendants of deformed and metamorphosed Keewatin rocks. Goldich and Peterman (1980) demonstrated that the Algoman intrusive rocks commonly contain abundant K-feldspar and have much higher Sr contents than Laurentian tonalite and trondhjemite. The Ottertail Lake intrusion, also with high overall Sr content, displays a fractionation trend of increasing Rb:Sr - 103 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 ratio toward its interior. Shirey and Hanson (1984, 1986) and Stern et al. (1989) further defined specific lithogeochemical characteristics of the Algoman rocks at Rainy Lake to show that they are also distinctive from other granitoid rocks at a global scale. Relative to their intermediate silica content (55-60%), they contain anomalous Mg, Sr, Ba, Ni, Cr and are strongly enriched in light rare earth elements. Stern et al. (1989) proposed their formation from hydrous melting of mantle that had been enriched large ion lithophile elements though prior metasomatism. Davis (1990) provided an estimate of 2693 +/- 2 Ma age for the Bear Pass pluton and coupled with the 2686+2/-1 Ma age of the Ottertail Lake intrusion (Davis et al. 1989), demonstrated that the sanukitoid magmatism spanned the time bracket for inferred for deposition of the Seine conglomerate and arenite above a profound angular unconformity. A recent study by Bjorkman et al. (2024) has demonstrated the widespread distribution of the sanukitoid suite of rocks across the Wabigoon Subprovince, including the Ottertail Lake Intrusion. This has been interpreted to represent a significant shift in magmatism at approximately 2690 Ma that can be explained by metasomatism and magmatism in a suprasubduction setting leading to collisional deformation and metamorphism that is commonly attributable to the Kenoran Orogeny. Deformation and Metamorphism The emphasis on protoliths and stratigraphic relationships that has historically dominated the discussion of the geology does not outweigh the fact that most of the rocks are clearly metamorphic tectonites as well. Lawson (1913) recognized this and attributed commonly observed foliation and lineation (“pencilling” in his terminology) to compressive deformation related temporally to the Algoman granitoid suite. Rocks in the southeastern part of the wrench zone have been metamorphosed to greenschist facies mineral assemblages and rocks of the amphibolite facies are dominant in the northwest (Fig. 8). Significant areas of retrograde metamorphism have also been noted (Peterman et al. 1972; Poulsen, 1984) and this has been taken to be the explanation why most geochronological approaches have yielded unreliable protolith ages. It is likely that the overall distribution of preserved prograde assemblages is the result a combination of both local contact and regional dynamothermal metamorphism. The common existence of minor structures of dynamothermal metamorphic origin such as foliation (Fig. 12c, 17f, minor folds (Fig. 19a, b) and lineation (Fig. 10a) are reflections of local strain. Rheological contrasts within and among lithological units have also been well established to be important in controlling the local strain intensity in the Rainy Lake area, particularly in the Seine conglomerate (Hsu, 1971; Jackson, 1982; Czeck et al., 2009). The highest strains are also common in features which are arguably shear zones in which strong foliation is accompanied by asymmetric distribution of foliation (Fig. 19c, d, e, f) that mimics the overall structural pattern in the wrench zone as a whole (Fig. 8). Following the lead of Peter Hudleston (1986) in the Vermilion district of Minnesota, dynamic interpretations invoking dextral transpression have been invoked by several authors to explain the overall structural style of the Rainy Lake wrench zone (Poulsen, 1986b; Borradaile et al., 1988; Poulsen et al., 1992; Czeck and Hudleston, 2003; Fernandez et al., 2013). Beyond the local importance of dynamothermal metamorphic fabrics, however, the larger structural features in the wrench zone also of considerable interest. Foremost among these is the angular unconformity at the base of the Seine sedimentary sequence in the southeastern part of the zone (Fig. 20a) and it also provides an ideal temporal reference point for understanding the deformational and metamorphic history of the area. As illustrated above, the fact that lithic clasts in the basal conglomerate above the unconformity show no evidence of pre-depositional metamorphic fabrics yet clasts throughout the Seine have been variably strained during post-depositional dynamothermal metamorphism is an important one. It illustrates the insufficiency of using the development of foliation alone as a means of tracking a protracted structural history. A second notable structural aspect at Rainy Lake is the stratigraphic evidence for significant overturning of beds in the northwestern part of the zone (Fig. 20b). Poulsen (1980) suggested that this might have resulted from the overprinting of early recumbent folds by younger upright ones but, given the observation that the first-formed foliation in these rocks is also folded in the Rice Bay dome, the possibility of late-overturning of what may have been at one time steep strata can’t be entirely ruled out. A third topic of importance is the fact that, since their recognition in the 1930’s, there also has been a great deal of attention paid to the major faults that define the boundaries of - 104 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B C D E F Figure 19: a) shortening and transposition of felsic dikes cutting Coutchiching biotite schist, north of Noden Causeway; b) folded felsic sills, Great River Road; c) asymmetric boudinage of the interior of a mafic dike relative to its foliated margins, Noden Causeway; d)) asymmetric boudinage in felsic metavolcanic rocks south of the Olive gold mine, e) asymmetric shapes of clasts in Seine meta-conglomerate adjacent to the Rainy Lake – Seine River Fault south of Seine River Bridge; f) tight asymmetric folds in mylonite, Little Turtle Lake landing. the wrench zone. The rocks that now help to define the Quetico Fault at Rainy Lake were originally mapped by Lawson (1913) as part of a narrow belt of “porphyroid gneiss” extending westward from Little Turtle Lake at Mine Centre to Cheery Island. He recognized that the red porphyroid gneiss “has a pronounced cataclastic structure and that the schistosity of the rock is referable to deformation involving shearing of the mass” (Lawson, 1913, p.94). He stopped short of relating the rocks to a fault, however, interpreting them instead to represent the deformed southern margin of a large granitoid batholith: this is somewhat ironic because he is the geologist who, by this time, had named the San Andreas Fault and had compiled the definitive technical report on the Great San Franciso Earthquake of 1906. By the time F.R. Harris remapped the area, however, it had been recognized that the rocks here belong to the greater than 350 km long Quetico Fault based on the interpretation linears on air photo mosaics (Parkinson, 1962). Harris (1974) went on to describe the rocks in the fault as crushed granite, augen gneiss and mylonite and, like Lawson before him, locally showed gradational contacts with adjacent banded gneissic rocks which he termed migmatite. Kennedy (1984) studied 14 sites along the entire Quetico Fault, including 3 in the Rainy Lake wrench zone, and concluded that the mylonitic foliation on average resulted, not strictly from cataclastic processes, but from ductile flattening - 105 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 A B Figure 20: Schematic cross-sections through a) Rice Bay – Bear’s Passage and b) the Bad Vermilion – Shoal Lake areas. See Figure 8 for the locations of the sections (adapted from Davis et al., 1989). The Quetico fault is located at the northern end of both sections. based on measured axial ratios of deformed mineral aggregates and object-object strain estimates. She also used quartz c-axis fabric measurements and analysis of brittle micro-faults and ductile shear zones to argue for overall dextral displacement on the fault. Kennedy (1984) showed that the microfaults and minor shear zones dominantly strike NW and have dextral shear sense. She further argued that transition from ductile behaviour (mylonite) to brittle is consistent with the current level of exposure representing deformation at a crustal depth of 10-15 km. Borrradaile and Kennedy (1982) also showed evidence of flow-banding in veins of pseudotachylite at Crowrock Inlet as evidence of frictional melting in the fault zone. Peterman and Day (1989) reported a Rb-Sr isochron age of 1947+/23 Ma to suggest that the pseudotachylite from both the Quetico and Seine River faults resulted from Proterozoic reactivation of the Archean faults. Metallogeny A commonly understated geological feature of the Rainy Lake wrench zone is the simple abundance of mineral occurrences within it in comparison to the adjacent areas on either side. Poulsen (2000b) enumerated 88 of them in total and demonstrated that they include examples that are representative of multiple deposit types (Figs. 8, 21) which, in turn, are thought to relate to multiple geological processes. Syngenetic deposits include stratabound metalliferous sediments in the mafic sections of the Keewatin including banded iron formation, pyritic massive sulfide deposits with locally anomalous zinc sulfides (Nickel Lake and Pocket Pond). Numeous Zn-Cu occurrences (Port Arthur Copper, Lochart Lake, Wind Bay, Gagne Lake, Pidgeon) demonstrably possess the descriptive of volcanic-associated massive sulfide deposits in general. Basal Cu+/-Ni sulfide mineralization (North Rock) and magnetite+/ilmenite mineralization (Seine Bay, Mironsky) is clearly associated with the Grassy Portage and Bad Vermilion Lake layered gabbroic intrusions (Poulsen and Hodgson, 1984). Quartzpyrite-molybdenite veins show a spatial association with Algoman granitoid rocks and sheeted veins of this type within the Bear Pass Pluton are similar in style to those in the deeper parts of granitoid-related - 106 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 main geological features. The western starting point of the road log Km 0.0 (92.4) is at the lookout tower on the waterfront in Fort Frances and the eastern ending point Km 92.4 (0.0) is at the highway bridge across the Seine River near Crilly. The highway distances are approximate and, although the stops are described from west to east, they can be visited in any order depending on topical interests. Figure 21: Metallogenic Summary of the Rainy Lake Wrench Zone Phanerozoic vein and stockwork deposits. The goldbearing quartz veins in the Mine Centre area which were the focus of a gold rush in the 1890’s (Coleman, 1894; Winchell and Grant, 1895), are readily classified in modern terms as “orogenic” deposits characterized by ribbon quartz, carbonate-sericite alteration and spatial control by minor shear zones (Poulsen, 1986a). A recurring question about the metallogeny of the Rainy Lake wrench zone concerns the apparent absence of economically viable mineral deposits compared to the numerous occurrences. While it is true the there is strong similarity between the make-up of the rocks in the Rainy Lake wrench zone and the central volcanic complexes at Chibougamau, Val d’Or and Noranda in the Abitibi subrprovince, the discrepancy in metal endowment may simply be explained in the context of the geological deposit types. For example, the metal endowment of syngenetic massive sulfide systems is thought to be negatively influenced by shallow water environments, the lack of a well-defined lithocap or by cooler upwelling fluids and this might apply to Rainy Lake. A notable characteristic of the orogenic Auquartz veins at Mine Centre the kinematic evidence for strike-slip stress conditions for vein formation at Rainy Lake in contrast to conditions for reverse faulting allowing for higher fluid pressure at Val d’Or in the Abitibi Subprovince (Poulsen et al., 1992). Road Log and Field Stops A traverse which follows Highway 11 along the Rainy Lake wrench zone provides an opportunity to examine representative outcrops which illustrate its The lookout tower at Fort Frances is located on the north shore of the Rainy River near its outlet from Rainy Lake (Fig. 22). The rock exposures which Lawson (1887) originally chose as a type locality of the Archean metasedimentary biotite schist at the Coutchiching Rapids were flooded upon construction of the power dam to the west of here circa 1906. Since then, representative outcrops that illustrate the Coutchiching Group have been described nearby at Ranier, Minnesota by Ojakangas et al. (1982, Stop 1) and Jirsa and Hemstad (2010, Stop 6-2). Drive east along Front Street and join Highway 11 and continuel eastbound from Fort Frances. Lake Road intersects the highway at Km 1.9 (90.5). Continue through the land of the Couchiching First Nation past Couchiching Drive at Km 3.3 (89.1). Note the discrepancy between the modern spelling compared that of the geological unit which was based on the version used topographically circa 1887. Continue past the C.N.R. Railway Crossing (Km 5.5 (86.9)) and over the crest of the Noden Causeway bridge and continue past the intersection with a side road to the north marked “Scenic Lookout”. This sideroad (Km 8.0, 84.4) leads to stop 13 of Czeck and Poulsen (2010). Continue eastward on Highway 11 and turn in to the next (unmarked) sideroad (Km 8.8, 83.6) which leads northward to a parking area beneath the hydro tower. This is STOP NC (Noden Causeway). This is an instructive stop (Fig. 23) in that this is one of the many islands in Rainy that would have been mapped both topographically by triangulation by W.H.C. Smith and geologically by Andrew C. Lawson in the 1880’s. The rocks here consist mainly of foliated quartz monzonite of which Lawson first assigned to the Laurentian but later revised to the Algoman intrusive suite which he described as “mica syenite” belonging to a larger Pukamo Island intrusion (Lawson, 1913). Harris (1974) correlated these rocks with the Rocky Islet Bay Complex west of Rice Bay which are comprised mainly of felsic to intermediate granitoid rocks of variable composition. The main unit - 107 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 22: Simplified geology of the Fort Frances segment. Field stops NC – Noden Causeway; GA – George Armstrong Drive Figure 23: Noden Causeway stop (NC) - 108 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 here is cut by a variety of dikes which offer contrasts in structural competence compared to the surrounding granitoid rock. Note the s-shaped asymmetric foliation pattern in one of the mafic dikes (site 1) that mimics the regional structural pattern of the Rainy Lake Wrench Zone as a whole (19c). Return to Highway 11 to resume the road log. Km 11.8 (80.6) – George Armstrong Drive intersects highway 11 from the east; turn in and park near the mailboxes to examine STOP GA (George Armstrong). This is also stop 11 of Czeck and Poulsen (2010) and Point of Interest 27 described in Pye (1968). This is the first area of significant exposure of the Coutchiching rocks northeast of their type locality at Fort Frances. Although the nature of the contact with the Keewatin rocks is obscure (Fig. 24), it is still a good place to examine the differences between the metasedimentary biotite schists which are cut by felsic intrusive rocks (site 1) and the metavolcanic Figure 24: George Amstrong Drive stop (GA) amphibole-biotite schists (site 3). Both units are now metamorphic tectonites which exhibit moderate to high strain but the variability of layer thickness in the metasedimentary units is consistent with their inferred origin as submarine turbidites (Ojakangas et al., 1982). Further evidence for the superimposed strain is evident at (site 2) where at least four generations of dikes cut the metasedimentary rocks and display the variable effects of folding and boudinage depending on their structural competence and pre-strain orientation with respect to bedding (see also Czeck and Poulsen (2010) and Druguet et al. (2008). Continue eastward along Highway 11 past Commissioners Bay which is the location of a zircon sample from a Keewatin felsic which yielded a U-Pb age of approximately 2727 Ma (Davis et al., 1989). Km 18.4 (74.0) – Windy Point Bridge Km 21.1 (71.3) – outcrops on both sides of Highway 11. This is STOP SM (Sims) and corresponds in part to the Windy Point locality described by Pye (1968). The outcrops here) display deformed pillowed and variolitic metabasalt which is a dominant lithology within the Keewatin volcanic sequence on the flanks of the Rice Bay Dome (Fig. 25). It is important to examine the exposure (site 1, Fig. 26)) carefully in three dimensions because primary pillow shapes which are inherently variable are further distorted by superposition of a moderate amount of tectonic strain. This result is log-shaped pillows with long axes that plunge moderately westward (Fig, 10a). The effects of the strain can be further appreciated by examining the cm-scale light-coloured patches that stand out against the darker amphibolitic background of the metabasalt (especially at site 2). They are varioles which predictably would have formed originally as spherical patches due to devitrification of glassy volcanic rock but here their shapes reflect their tectonic distortion with a flat aspect corresponding to a foliation and a long axis which plunges westward in the foliation. Note also that the dark pillow selvedges offer rheological contrasts with the rest of the basaltic material so that the down-plunge elongation is also expressed in places in the outcrops by boudinage of individual pillows. Pye (1968) described these outcrops without reference to their volcanic origins at all while still emphasizing the lineation and the sets of joints perpendicular to it. Even where the pillows are clearly defined the considerable strain makes it difficult to draw satisfactory conclusions about primary stratification and directions of younging. Harris (1974) and Poulsen (1980) suggested, albeit with some doubt, that the stratigraphic section in this area faces downward and eastward. Km 24.9 (67.5) – The Nickle [sic] Lake Shores Road which intersects Highway 11 from the south leads to STOP NL (Nickel Lake). This was stop 1 of Poulsen (1982). This area illustrates the fact that, although the term Keewatin is synonymous with metavolcanic protoliths, it also contains clastic and chemical interflow sedimentary units which include oxide, sulfide, carbonate and silicate facies of iron-formation. These rocks are important from at structural point of view in that they typically have sharp magnetic and - 109 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 25: Simplified geology of the Swell Bay segment. Field Stops: SM-Sims; NL-Nickel Lake; MB – Moran’s Bay; GR-Great River Rd.; PP-Pocket Pond; BC- Belacoma; GP-Grassy Portage; BL- Bear’s Passage boat launch; BB- Bear’s Passage bridge; TB-Tunnel Bay Figure 26: Sims stop (SM). - 110 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 electromagnetic geophysical responses which aids in the definition of their position in areas of poor exposure. The rock here (Fig. 27, site 1) is typically referred to as chert-magnetite, banded iron formation (BIF) and is a lithology that is commonly folded at all scales. At Nickel Lake the iron-formation defines a structural synform (historically the Nickel Lake Syncline) which plunges shallowly westward along axes coincident with those of the minor folds and with the axes of maximum elongation in the adjacent volcanic rocks. The curved traces of folds observed here in a downplunge view was originally interpreted by Poulsen (1980) to present a type 3 (coaxial) fold interference pattern. It is equally possible, however, that they result from a single deformation with a strong westward plunging linear component of strain (i.e. L-s tectonite). potentially represent coeval subvolcanic intrusions or younger sills Algoman which are responsible for the cross-cutting relationships. Both lithofacies display prominent polycrystalline quartz aggregates which are likely deformed phenocrysts which help define both the tectonic foliation and a prominent lineation which plunges shallowly eastward at this locality (Fig. 15f). Figure 28: Moran’s Bay stop (MB) Km 29.0 (63.4) intersection between Highway 11 and Highway 502 (Fig. 25). This is STOP GR (Great River Rd.) which corresponds to Stop 10 of Czeck and Poulsen (2010). Figure 27: Nickel Lake stop (NL). Km 26.9 (65.5) – outcrops on both sides of highway 11 but a particularly large one on the south side. This is STOP MB (Moran’s Bay) and is described as Stop D.1 in Poulsen and Wood (1982). The outcrop is located on the south limb of the prominent antiformal Rice Bay Dome (25). It provides ample illustration of the rocks Lawson (1914) mapped as Laurentian granite and granite gneiss in the interior of the dome (Fig. 28). Both Lawson (1913) and Harris (1974) interpreted the unit to be at least in part intrusive into the mantling Coutchiching metasedimentary rocks but the details remain in considerable doubt. R.W. Ojakangas was the first to suggest that the wispy banded, quartz-phyric, grey, foliated quartzofeldspathic can also be interpreted as a deformed rhyolite. This unit yielded a U-PB zircon age of 2725+/-2 Ma (Davis et al., 1989). It is cut by more competent sheets of coarser quartz-feldspar porphyry (Fig. 15e) which could Folded quartz-phyric intrusions on the north side of Highway 11 west of the intersection (site 1, Fig. 29) cut amphibole-biotite schists containing local ironformation which were included with the Coutchiching biotite schist on the maps of Lawson (1914) and Harris (1974) but which show greater similarity to Keewatin units elsewhere. The porphyritic felsic intrusions have been generally included in the suite of Laurentian intrusions but the molybdenite-bearing quartz veins exposed here are also a characteristic of Algoman intrusions elsewhere. Despite these uncertainties of interpretation and the somewhat transitional nature of the contacts, it is clear these rocks serve to separate the inner core of the Rice Bay dome from a structurally higher annular band of moderately southeastwarddipping Couchiching biotite schists which are well exposed approximately east of the intersection (site 2). It is also possible to make a short side-trip form this intersection northward along highway 502 for 2.2 km to its intersection with the Baseline Bay side road which enters from the east. This is STOP PP (Pocket Pond) and corresponds to Stop D.2 of Poulsen and Wood (1982). - 111 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Km 30.2 (62.2) – bush road and outcrops on north side of Highway 11. This is STOP BC (Belacoma) corresponding to stop 3 of Poulsen (1982, stop D.3 of Poulsen and Wood (1982) and stop 5 of Hinz (2010). Figure 29: Great River Road stop (GR) The critical outcrops (Fig. 30, site 1) that demonstrate the overturned stratigraphic section on the northern limb of the Rice Bay dome are now heavily overgrown and no longer instructive. A good sense of the nature of the northeastward-dipping contact between the Coutchiching metapelites and the distinctive green, magnetic ultramafic unit which here represents the Keewatin volcanic rocks can still be observed along Highway 502 (site 2). Continuity of the lithostratigraphic units and their moderate northeasterly dips in this area were established with the assistance of ground magnetic and electromagnetic surveys and by diamond drilling which targeted Cu-Zn mineralization associated with the interflow iron-formation units in the section. Although the contacts among the units are sharp and well defined there is no conclusive evidence for them to be erosional-depositional in origin but the evidence for an overturned volcanic sequence is sound (Fig. 30). This is a continuation of the Coutchiching-Keewatin contact which extends southward from Pocket Pond and westward to Nickel Lake and sharply defines the eastern closure of the Rice Bay Dome. The volcaniclastic ferropicrite unit here is exposed over a wider area than at Pocket Pond and the full nature of the contact is uncertain. The ultramafic rocks near the contact with the structurally underlying Coutchiching biotite schists (Fig. 31, site 1) are foliated as but appear to be progressively less deformed eastward (sites 2 and 3). Nonetheless, graded bedding of reasonable quality suggests the Coutchichiing strata are overturned in support of the observations at Pocket Pond. The cluster of outcrops near the beaver pond (site 3) have been documented by Schaefer and Morton (1991), Goldstein and Franceis (2008) and Hinz (2010) and the inference is that this unit is composed of relatively rare mantlederived ultramafic coherent and pyroclastic rocks that locally contain well-preserved accretionary lapilli (Fig. 10f). Return to Highway 11 and resume the road log. Figure 31: Belacoma stop (BC) Km 31.3 (61.1) C.N.R. overpass Km 31.9 (60.5) – numerous outcrops on both sides of Highway 11; safe parking is available beneath the powerline on the west side of the highway (Fig. 32). This is Stop GP (Grassy Portage) and corresponds to Stop D.4 of Poulsen and Wood (1982). Figure 30: Pocket Pond stop (PP) The gabbroic rocks exposed here are part of the metamorphosed Grassy Portage layered mafic intrusion and include plagioclase-rich leucogabbro (site 1) that gives way southward to garnet-bearing quartz- 112 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 ferrodiorite (site 2). The garnets are metamorphic porphyroblasts that likely crystallized owing to the favourable bulk composition of the diorite which has a higher Fe/Mg ratio and silica content than the leucogabbro. Lawson’s 1914 map of the area portrayed the leucogabbro as “hornblende gabbro” alone as an intrusion within the Keewatin while including the gabbro and melagabbro to the north and the garnetbearing quartz diorite to the south as Keewatin metavolcanic rocks. This inferred symmetry led to his interpretation of a synclinal axis centred on the leucogabbro but Harris (I974), Poulsen (1980) and Poulsen and Hodgson (1986) recognized all three lithofacies as distinctively different phases of a single layered mafic intrusion that shows progressive southward, upward in a stratigraphic sense, chemical and mineralogical fractionation. contact (site 3) is consistent with southward younging in the meta-turbidites and contradicts the structural order of the rocks based on dip alone. It is, however, consistent with the southward younging implied by the fractionation within the Grassy Portage layered mafic intrusion. Return to Highway 11 to resume the road log Figure 33: Bear’s Passage Boat Launch stop (BL) Km 36.4 (56.0) – Taylor’s Road intersects Highway 11 from the north Km 37.0 (55.4) – parking area and scenic view on South side of the highway (Fig. 34). This is STOP BB (Bear’s Passage Bridge) corresponding to Stop 7 of Poulsen (1982) and Point of Interest 2 of Pye (1968). Figure 32: Grassy Portage stop (GP) Km 33.6 (58.8) - the side road on the east side of Highway 11 leads to the boat launch at Bear’s Passage where parking is available at the lakeside (Fig. 33). This is STOP BL (Bear’s Passage Boat Launch) corresponding to Stop D.5 of Poulsen and Wood (1982) and locality 20 of Uglow (1913). This critical area of outcrop illustrates one of the most contentious points of the Seine-Coutchiching problem. The Keewatin rocks which are cut locally by a foliated lamprophyre dike structurally overlie gabbroic rocks of the Grassy Portage layered intrusion (site 1.) The Coutchiching rocks are staurolite-bearing biotite schists (site 2) and locally display evidence of primary graded bedding with is enhanced by the distribution of porphyroclasts in upper parts of individual beds. Graded bedding which can be observed directly adjacent to the relatively sharp Keewatin-Coutchiching The eastward dipping Coutchiching biotite schist, as exposed on the north side of the highway (site 2). is cut by granodiorite of the Bear Pass Pluton which contains sheeted quartz-pyrite-molybdenite veins which are exposed on both sides of the bridge (sites 1 and 3) The view southward from the lookout features Swell Bay and the belt of Keewatin volcanic rocks to the south of it. The Keewatin-Coutchiching contact is located on Morton Island to the southwest. Km 37.7 (54.7) – Bear Pass Road intersects Highway 11 from the north. From this location it is possible to make a side trip to STOP TB (Tunnel Bay) by driving northward for 1.3 km to the C.N.R. tracks and taking the first dirt road uphill to an exposure of Coutchiching metasedimentary rocks (Fig. 35). This area is near Tunnel Bay and localities 5 and 6 of Uglow (1913). These outcrops are located on the eastern limb of the antiformal culmination in the Bear’s Passage area. The demonstration of the existence of the antiform - 113 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 OS (Old Station Road) where the field relationships are comparable to those at Morton Island (Stop D.6 of Poulsen and Wood (1982)). Figure 34: Bear’s Passage bridge stop (BB) was essential to Lawson’s (1913) interpretation of the Coutchiching strata in the interior of this structure. It is also the location where D.W. Davis first demonstrated the effects of zircon inheritance from the Coutchiching metasedimentary rocks by felsic dikes related to the Bear Pass Pluton. One of the dikes near the stop of a steep outcrop can be viewed to the east at (site 2). An additional point of interest in these exposures (sites 1 and3) is that the main foliation is locally crenulated by a steep, northwest striking, transecting cleavage (S3 of Poulsen, 1980), which is particularly prominent in a 2 km-wide northwesterly trending corridor through this area. Although locally dominant at the mesoscopic and mircroscopic scales, where crenulation of the main biotite-rich foliation and rotation of metamorphic porphyroblasts are both evident, the effects of this deformation at the macroscopic scale are negligible. Return to Highway 11 to resume the road log Km 40.8 (51.6) – Old Station Road intersects Highway 11 from the north (Fig. 36). This is STOP Figure 35: Tunnel Bay stop (TB) Highway 11 at this locality (Fig. 37) is approximately parallel to the strike of stratification in the Coutchiching meta-sdedimentary rocks as well as to their mapped contact with Keewatin meta-volcanic rocks (Harris, 1974). The overall dip of bedding is steep to the southeast and in places a steep cleavage with a more northerly strike transects bedding to form a moderately eastward plunging intersection lineations. Exposure is plentiful but the clearest features of the Coutchiching beds are illustrated in flat outcrops on the south side of Highway 11 (site 1). The rocks here are metamorphosed to greenschist facies assemblages and primary features are reasonably well preserved: polarity in graded beds consistently indicate a northward direction of younging which is away from Keewatin volcanic rocks which are exposed at the shore of Rainy Lake south of here. Km 43.3 (47.9)) – Ottertail Landing Road intersects Highway 11 from the north. Km 46.2 (46.2) – a side road to a communications tower intersects Highway 11 from the north: turn in and park (Fig. 38). This is STOP OW (Ottertail West). The field relationships exposed in the outcrops east of the intersection on the north side of Highway 11 are comparable to those at stop 1 of Czeck and Poulsen (2010) which is located approximately 1 km to the west. This is an area in which a roof pendant composed of foliated metavolcanic and metasedimentary schists has been variably incorporated into granitoid rocks of the Ottertail Lake intrusion. The outcrops here provide a rare case where highway improvement has also resulted in outcrop improvement. A marginal phase of the Ottertail Lake intrusion (site 1) is composed of diorite containing abundant mafic xenoliths (Fig. 18d). Magmatic breccias (Fig. 18e) are well exposed along the highway to the east (site 2) and, at one location nearby, a narrow NNE-striking mylonitic zone cuts the intrusive rocks. The most critical point made by Lawson (1913) and most observers since is that there is abundant visual evidence for intrusion of felsic magma into previously foliated metamorphic tectonites. Km 47.5 (44.9) – the outcrop on the north side of the road was sampled by D.W. Davis to yield a U-Pb zircon age of 2686+/-3 Ma for this part of the Ottertail Lake intrusion. - 114 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 36: Simplified geology of the Ottertail Lake segment. Field Stops: OS- Old Station Rd; OW: Ottertail Lake West; OE-Ottertail East Figure 37: Old Station Road stop (OS) - 115 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Turtle River Road. Km 58.8 (33.6) Patten Park picnic area Km 62.0 (30.4) – Low outcrops are present on both sides of highway (Fig. 40) and a rusty waste dump is visible across a marshy area on the north side of Highway 11. This is STOP PA (Port Arthur Copper) which was stop 9 of Poulsen (1982) and Point of Interest 22 in Pye (1968). Figure 38: Ottertail West stop (OW) Km 48.2 (46.2) – Pearson’s Road intersects Highway 11 from the north Km 53.9 (38.5) – the outcrops of Ottertail Lake intrusive rocks exposed here are described as Stop 2 in Czeck and Poulsen (2010). Km 56.1 (36.3) – outcrops on both sides of the road expose the eastern margin of the Ottertail Lake Intrusion. This is STOP OE (Ottertail East) and corresponds in part to Stop D.7 of Poulsen and Wood (1982). The easternmost outcrop on the north side of Highway 11 (site 1, Fig. 39) exposes deformed spherulitic and flow-banded rhyolite that is common in the Keewatin volcanic section in this part of the belt. It is cut by granitoid phases or the Ottertail Lake Intrusion, including a distinctive feldspar-phryic variety containing xenoliths (site 2). The abundance of xenoliths decreases westward in these outcrops (site 3). Km 56.4 (36.0) intersection of Highway 11 and Figure 39: Ottertail East stop (OE) Access the rusty area from the west side of the water and cross a small Beaver Dam to reach the large area of exposure (Fig. 41). The main mineralized lithology is composed of foliated amygdaloidal andesite (Fig. 10c) containing disseminated and semi-massive lenses of pyrite, chalcopyrite and sphalerite (site 1). Stratified, rusty felsic volcanic rocks are exposed on the north side of the outcrop area (site 2). This is but one of several occurrences of syngenetic sulfide deposits hosted by the felsic portions of the Keewatin volcanic section extending more than 25 km southwestward beyond Wind Bay. It is also noteworthy that the base metal deposits are located up-section northward from the syn-volcanic Bad Vermilion Lake intrusive complex (Fig. 40). Km 63.4 (29.0 side road intersects Highway 11 from the north Km 67.0 (25.5) -the Mine Centre Road intersects Highway 11. This road can be followed north to Little Turtle Lake by travelling for 1.0 km to Government Road and continuing .5 km to the C.N.R. tracks. Bear right at the intersection with Queen St. and follow the dirt road to the public boat launch site. The outcrops near the shoreline constitute STOP LT (Little Turtle Landing) which corresponds to Stop D.9 of Poulsen and Wood, 1982). Lawson (1913) mapped the rocks that are exposed here as a distinctive lithological unit which he described as “porphyroid gneiss”. In doing so, he effectively defined a 60 km E-W segment of what is now known as the Quetico Fault without explicit reference to faults but certainly recognized the overall significance of the rock type in “that it has a pronounced cataclastic structure and that the schistosity of the rock is referable to deformation involving shearing of the mass” (Lawson, 1913. P.94). Today the lithologies which he described are regarded as variably deformed fault rocks which include protomylonite (site 1) which is exposed in the outcrop east of the parking area and mylonite (site 2) along the shore of Little Turtle Lake. - 116 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 40: Simpified geology of the Mine Centre segment. Field Trip Stops: PA-Port Arthur Copper; LT-Little Turtle landing; FG: Ferguson; GS-Golden Star; WC-Windy City Rd. Regrettably, a recently constructed dock partially obscures the best exposure of the folded mylonite (Fig. 19f) as described in Poulsen and Wood (1982). Km 68.2 (24.2) The Shoal Lake Road meets Highway 11 from the south (Fig. 40). This road leads to what is arguably the most significant geological feature in the entire belt – the angular unconformity at the base of the Seine Group metasedimentary rocks. Follow the (in places rough) Shoal Lake public road southward for 3.3 km to a point where it is met from the east by a recently constructed but as yet uncompleted sideroad. The is STOP FG (Ferguson) and outcrops in this area Figure 41: Port Arthur Copper stop (PA) Figure 42: Little Turtle Landing stop (LT) Return to Highway 11 and resume the road log - 117 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 offer a good view of the Bad Vermilion tonalite which Lawson assigned to his Laurentian suite of granitoid rocks. The recent excavation (site 1) has exposed the tonalite and small quartz veins with adjacent sericiteankerite alteration of the style exposed at the Ferguson gold prospect to the north (site 2). Lawson (1913) demonstrated conclusively that the tonalite cuts both the Bad Vermillion gabbro-anorthosite to the west and Keewatin volcanic rocks to the north which include moderately northward dipping interflow chertcarbonate units and a northward younging unit of pillow basalt. conglomerate (Fig. 17a, b) it is also clear that even the least competent lithic clasts possessed no tectonic fabric at the time of deposition across strata with a preexisting steep dip. Return northward to Highway 11 and continue eastward along it. Km 76.5 (15.9) an unmarked bush road meets Turn around and proceed back northward along the Shoal Lake Road for 2.2 km to a small rise with a low outcrop on the east side; pull to the right side of the road and park as safely as possible (Fig. 44). This is Figure 44: Golden Star stop (GS) Figure 43: Ferguson stop (FG) STOP GS (Golden Star) and the site of Stop D.10 of Poulsen and Wood (1982) and the contact described by Uglow (1913) as being marked by “brown flags” for the International Geological Congress Field Trip led by Lawson. The field relationships here have also been described and discussed more recently as Stop 1 of Czeck and Fralick (2020). The base of the Seine Group here dips gently eastward at high angle to stratification in the Keewatin rocks. Much of the outcrop (site 1) is now grown over but five small patches have been recently cleaned to clearly show the west to east transition from quartzbearing tonalite a), tonalite sand with rare clasts (b) to angular conglomerate (c) with interstitial sand (fanglomerate of Lawson) to polymictic pebble and cobble conglomerate (d, e). Although there is evidence of a weak tectonic foliation superimposed on the Highway 11 on the south side; pull in and park. This is STOP WC (Windy City road). The increasingly overgrown leads southward from here for approximately 500 metres to a sign which explains how a windstorm in 1988 flattened trees over a seven km2 area resulting in its nickname of “Windy City”. Reclamation of the area resulted in local removal of shallow glacial overburden to produce two-dimensional pavement exposures of cobble to boulder conglomerate which show the rheological effects of superimposed strain. These outcrops comprise the “Forest Tour” Stop 5 of Czeck and Poulsen (2010)) can be reached by continuing another 250 m southward beyond the sign and following the second sideroad to the southwest (approximate UTM NAD 83 Zone15 N: 536 800E, 5 398 500N). The outcrops exposed at the intersection along highway at its intersection with the Forest Tour Road, however, make for a good and easily accessible substitute stop. The outcrops occur along both sides of the highway and serve to illustrate three important aspects of Seine Group as a whole. The first is the distinction between the two main lithofacies: polymictic clast-supported conglomerate (site 1) versus thick-bedded, locally cross-bedded, arenaceous sandstone (site 2) which occupies the middle part of the Seine stratigraphic - 118 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 consistent with that of rocks which are regarded to be part of the Algoman suite (Davis et al., 1989). Km 78.4 (14.0) the Manion Lake Road meets Highway 11 from the north (Fig. 46). Km 82.2 (10.8) Horsecollar Junction – the road to the south leads to the Seine River village and the outcrops the deformed conglomeratic facies of the Seine Group on the north side of the highway constitute Stop 5 of Czeck and Fralick (2002). Km 92.1 (0.3) the Crilly Road meets Highway 11 from the north. Figure 45: Windy City Road stop. section – most evidence suggests that the strata young southward toward the polymictic conglomerate units. Second, a good three-dimensional view of the shape fabrics shows both elements of both foliation and eastward plunging lineation as well as the rheological differences in response to the bulk strain by clasts of different original composition and grain size. Third, a population of granitoid clasts is particularly noticeable in this part of the Seine stratigraphic section and these were commonly assumed to have been sourced in the Laurentian granitoid suite. A sample from this area (site 3) was collected and analysed by D.W. Davis to demonstrate that the age of a granitoid clast was actually Km 92.4 (0.0) Highway bridge across the Seine River (Fig. 47). This is STOP SR (Seine River Bridge) and is also described as Stop D12 of Poulsen and Wood (1982) and Stop 5 of Czeck and Fralick (2002). The outcrop southeast of the bridge provides an excellent visual representation in cross-section of the mixed arenite-conglomerate facies of the Seine Series. The overprinting steep foliation corresponds to pronounced shape fabrics in clasts at high angle to bedding in pebble conglomerate and the comparable shortening across the foliation is manifested by steepening and distortion of the foresets in the crossbedded sandstone units. The beds dip shallowly northward and this also corresponds to the inferred Figure 46: Seine River segment - 119 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Geological Magazine, v. 67, p. 77-92. Bailey, E.B., 1927, Across Canada with Princeton; Nature, v.120, p.673-675. Bass, M. N., 1961, Regional tectonics of part of the southern Canadian Shield; Journal of Geology, v. 69, p. 668702. Bauer, R.L., Czeck, D.M., Hudleston, P.J., Tikoff, B., 2011, Structural geology of the subprovince boundaries in the Archean Superior Province of northern Minnesota and adjacent Ontario; in Miller, J.D., Hudak, G.J., Wittkop, C., and McLaughlin, P.I., eds., Archean to Anthropocene: Field Guides to the Geology of the Mid-Continent of North America: Geological Society of America Field Guide 24, p. 203–241. Figure 47: Seine River Bridge stop. direction of stratigraphic younging. Although not formally defined as a type locality for the Seine Series, the outcrops here are arguably a good reference locality. References Adams, F.D., Bell, R., Lane, A.C., Leith, C.K., Miller, W.G. and Van Hise, C.R., 1905, Report of the special committee for the Lake Superior Region; Journal of Geology, v.13, p.89-104. Alderman, D.J., 1988, Rice Bay geological mapping and lithogeochemical sampling; unpublished geological report, Falconbridge Limited, Winnipeg, 51 p. Alt, D.D., 1958, A review of the geology of Rainy Lake; unpublished M.S. thesis, University of Minnesota, 73p. Ashwal, L.D., Morrison, D.A., Phinney, W.C. and Wood, J., 1983, Origin of Archean anorthosites: evidence from the Bad Vermilion Lake anorthosite complex, Ontario; Contributions to Mineralogy and Petrology, v. 82, p. 259-273. Ayer, J.A. and Davis, D.W., 1997, Neoarchean evolution of differing convergent margin assemblages in the Wabigoon Subprovince: geochemical and geochronological evidence from the Lake of the Woods greenstone belt, Superior Province, northwestern Ontario; Precambrian Research, v. 81, p. 155-178. Ayres, L.D., 1970, Synthesis of Early Precmbrian stratigraphy north of Lake Superior; Institute on Lake Superior Geology Proceedings, Thunder Bay, Ontario, Abstract, p. 8. Ayres, L.D., 1969, Early Precambrian Stratigraphy of Part of Lake Superior Province Park, Ontario, Canada and its Implications for the Origin of the Superior Province; unpublished Ph. D. thesis, Princeton University. Bailey, E.B., 1930, New light on sedimentation and tectonics; Beakhouse, G.P., 1984, Reconnaissance investigations of granitoid and medium to high grade metasedimentary terrains: volcanic components and mineral potential; in Summary of Field Work, 1984; Ontario Geological Survey Miscellaneous Paper 119, p. 14-18. Bjorkman, K.E., Lu, Y., McCuaig, T.C., Kemp, A.I., Hollings, P., 2024, Linked evolution and in situ growth of the Wabigoon superterrane, Superior Craton: evidence from zircon U-Pb isotopes and whole-rock geochemistry. Precambrian. Research, v. 404, 107341. Blackburn, C.E., 1980, Towards a mobilist tectonic model for part of the Archean of Northwestern Ontario; Geoscience Canada, v. 7, p. 64-72. Blackburn, C.E., 1973, Geology of the Otukamamoan Lake area, Districts of Rainy River and Kenora; Ontario Division of Mines, Geological Report 109, 42p. Accompanied by Map 2266, scale 1 inch to 1 mile. Blackburn, C.E., Bond, W.D., Breaks, F.W., Davis, D.W., Edwards, G.R., Poulsen, K.H., Trowell, N.F. and Wood, J., 1985, Evolution of Archean volcanicsedimentary sequences of the Western Wabigoon subprovince and its margins: a review; in Evolution of Archean Supracrustal Sequences, edited by L.D. Ayres, P.C. Thurston, K.D. Card and W. Weber; Geological Association of Canada, Special Paper 28. p. 89-119. Borradaile, G.J., 1982, Comparison of Archean structural styles in two belts of the Canadian Superior Province; Precambrian Research, v. 19, p. 179-189. Borradaile, G.J. and Kennedy, M.C., 1982, Pseudotachylite; in Atlas of Deformation and Metamorphic Rock Fabrics, edited by G.J. Borradaile, M.B. Bayly C. McA. Powell; Springer Verlag, Berlin, Heidelberg, New York, p. 366-367. Borradaile, G.J., and Poulsen, K.H., 1981, Tectonic deformation of pillow lava; Tectonophysics, v. 79, p. T17-T26. Borradaile G., Sarvas, P., Dutka, R., Stewart, R., and Stubley, - 120 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 M., 1988, Transpression in slates along the margin of an Archean gneiss belt, northern Ontario - magnetic fabrics and petrofabrics; Canadian Journal of Earth Sciences, v.25 , p. 1069-1077. Bruce, E.L., 1925, The Coutchiching rocks of the Bear’s Pass section, Rainy Lake; Royal Society of Canada Transactions, Section IV, v.19, p. 42-46. Bruce, E.L., 1927, Coutchiching delta; Geological Society of America Bulletin, v.39, p.771-782. Carreras, J., Czeck, D. M., Druguet, E., Hudleston, P. J., 2010, Structure and development of an anastomosing network of ductile shear zones; Journal of Structural Geology, v. 32, p. 656-666. Coleman, A. P., 1898, Clastic Huronian rocks of western Ontario; Geological Society of America Bulletin, v. 9, p. 223-238. Coleman, A.P., 1894, Gold in Ontario: it’s associated rocks and minerals; in Report of the Bureau of Mines, Ontario, v.4, p. 35-100. (printed 1985) Cooke, H.C., 1926, Between the Archean and Keweenawan is the Huronian; Royal Society of Canada Proceedings, series 3, v.19, sec. 4, p. 17-37. Cram, I.H., 1932, The Rest Island granite of Minnesota and Ontario; Journal of Geology, v.40, p.270-278. Czeck, D. M. and Hudleston, P. J., 2003. Testing models for obliquely plunging lineations in transpression: a natural example and theoretical discussion. Journal of Structural Geology 25, 959-982. Czeck, D. M., Maes. S. M., Sturm, C. L., and Fein, E. M., 2006. Assessment of the relationship between emplacement of the Algoman plutons and regional deformation in the Rainy Lake region, Ontario. Canadian Journal of Earth Sciences 43, 1653-1671. Czeck, D. M. and Poulsen, K. 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Zhou, S., Polat, Ali, Longstaffe, F., Yang, K.G., Fryer, B.J. and Weisener, C., 2016, Formation of the Neoarchean Bad Vermillion Lake Anorthosite Complex and Spatially Associated Granitic Rocks at a Convergent Plate Margin, Superior Province, Western Ontario, - 124 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Canada; Earth Sciences Publications, v. 10 (https:// ir.lib.uwo.ca/earthpub/10) - 125 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Trip 6 - Amethyst Deposits of Thunder Bay Stephen Kissin Department of Geology, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada and Greg Paju Resident Geologist Program, Ontario Geological Survey, Ministry of Energy and Mines, Thunder Bay, Ontario, P7E 6S7, Canada Canada Introduction Properties of Amethyst Amethyst, occurring in abundance in the Thunder Bay region, is purple gemstone variety of α-quartz. It has been known for some time that an iron impurity in quartz is the underlying source of amethyst coloration (Holden, 1925). However, incorporation of iron of alone cannot account for the formation of amethyst, as many varieties of quartz contain trace amounts of iron, yet amethyst is relatively rare, and large deposits of amethyst are very rare. interstitial sites. The color of amethyst is produced by absorptions of light in the visible region of the spectrum owing to the presence of Fe4+, as originally shown by Cox (1977). The proposed mechanism requires the coincidence of four geological conditions for the formation of amethyst: (1) The incorporation of Fe and Al, as well as Na or Li. This is not a limiting condition, as the small concentrations of these trace elements are readily available in hydrothermal solutions. (2) A source of ionizing radiation, either from U and Th or 40K in order to produce the defects in Fe and Al. (3) Deposition at generally rather shallow depth such that oxidizing conditions prevail and iron is in the form of Fe3+. (4) Deposition with a temperature range for the stability of Fe4+, the source of amethyst coloration. In a series of papers by Cohen and coworkers, culminating in a summary in Cohen (1989), a simultaneous sequence of reactions was proposed for the formation of amethyst. (1) (Al–O)- → (Al–O)° + eIonizing radiation forms a hole center from oxidizing the substitutional Al-O bond. (2) Na+ + e- → Na° Electron from step 1 is trapped by an interstitial alkali metal ion. (3) Fe3+int → Fe4+int + eInduced ionizing radiation forms a trapped hole center via oxidizing the interstitial Fe3+. (4) (Al–O)°+e- → (Al–O)Trapped hole center is satiated as [AlO°] is reduced via gaining the electron from step 3. The presence of iron is positions interstitial with respect to the SiO4 framework was established by Adekeye and Cohen (1986), in noting its correlation with pervasive Brazil law twinning in colored sectors of amethyst crystals. Data on incorporation of the alkalis Na, K and Li and trivalent Al and Fe in quartz were reported by Deer et al. (1963), who further noted that the incorporation of Al3+ (and presumably Fe3+), is compensated by the incorporation of Na+ or Li+ The mechanism proposed above is consistent with observed data and provides a logical mechanism for the formation of amethyst. However, Rossman (1994) noted that there are unestablished factors in the model such that its acceptance is tentative. Crystal forms expressed in amethyst are invariably simple, consisting only of combined positive {101} and negative {011} rhombohedra. The faces of one of the forms are generally largely and are designated as the major rhombohedron r, and the other form is designated as the minor rhombohedron z (Fig. 1). The only other form occasionally observed is the ditrigonal prism m (Frondel, 1962). Amethystine coloration is unevenly distributed in the crystal, generally with concentration in the major rhombohedral forms, in which Brazil law twins are also concentrated (Fig. 2; Frondel, 1962). The orientation of Brazil law twins in Figure 2, is typical - 126 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 2. Etched basal α-quartz illustrating the typical occurrence of Brazil law twinning in which alternate bands contain left- and right-handed α-quartz (after Frondel, 1962). Figure 1. A typical amethyst crystal viewed perpendicular to the c-axis, illustrating the combination of positive {101 ̅1} and negative {011 ̅1} rhombohedra. of their occurrence in α-quartz; however, in amethyst the twins are polysynthetic with a typical width of 0.1 mm (McLaren and Pitkethly 1982). The twin plane of the Brazil law is {101}, which separates right-handed and left-handed orientations of quartz. McLaren and Pitkethly (1982) demonstrated that the composition plane of the Brazil law twin provides space for incorporation of Fe3+ and that iron is preferentially concentrated along this composition plane in amethyst. Amethyst’s Name and Colour Origins The word amethyst has its origins from the ancient Greek word amethystos which may be translated as “not drunken”, from the Greek a-, “not” + methustos, “intoxicated”, as the gemstone was believed to prevent or lessen the effects of drinking alcohol. There is a common theme regarding the mythological origin of amethyst’s purple colouration. Bacchus (Dionysus to the Romans); the Greek god of winemaking, orchards, fruit, vegetation, fertility, festivity, insanity, ritual madness, religious ecstasy, and theatre, pursuing a maiden named Amethyste, who was refusing his affections. Amethyste prayed to the gods to remain chaste, a prayer answered by the goddess Artemis (Diana to the Romans), who transformed her into a white stone. Bacchus humbled by Amethyste’s desire to remain chaste, poured wine over the stone as an offering, dyeing the crystals purple. In another variation the god was insulted by a mortal, and vowing to slay the next mortal who crossed his path in retaliation created fierce tigers to carry out his wrath. The hapless mortal a young woman, Amethystos, was on her way to the shrine of the goddess Diana, when the tigers fell upon her. Her life was spared by the goddess, but the price was being transformed into a statue of pure quartz. Seeing what his anger had done, a remorseful Dionysus was so moved that tears of wine poured from his eyes onto Amethystos, staining her stature purple. Despite the belief in this origin story, there are no ancient texts supporting the myth, as compared to the ancient period that supposed birthed this story, it’s quite recent as it was written in 1569 by the French Renaissance poet Rémi Belleau (1528–1577), in the poem “L’Amethyste, ou les Amours de Bacchus et d’Amethyste” (Amethyst or the loves of Bacchus and Amethyste; Belleau, 1576). Amethyst Deposits in the Thunder Bay Area In his summary of the history of amethyst in the Thunder Bay area, Patterson (1985) reported that as early as 1642, Radisson described the use of - 127 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 “torquoise” as a gemstone by local indigenous peoples. Amethyst was an associated mineral in most of the lead-zinc and silver mines, and attracted the interest of a few prospectors. In the early 1860s, the McEachern brothers prospected for amethyst in the Thunder and Black Bay areas. In 1862, they mined two tons of amethyst crystals, which they barged to Toronto to sell in that city. About the same time, a shipment of amethyst from the Thunder Bay area was sold in Montreal. The success of the mineral as a valued item for sale even in an unprocessed state and the ease of mining encouraged other prospectors and developers to try searching for and producing amethyst (Garland 1994).In the 1880s, amethyst was mined northeast of Thunder Bay in a place now called Amethyst Harbour. Interest in Thunder Bay amethyst declined around the turn of the century with the development of deposits of high quality and inexpensive amethyst from Brazil. The deposit that became known as the Amethyst Mine Panorama was originally discovered in 1935. When the fire tower was built in the 1950s, near Elbow Lake in McTavish Township, the large amethyst veins were uncovered by the roadbuilders. In the early 1960s, the area was staked, and trenches exposed the veins in what is now the open pit for the mine. In large vugs near the surface of the vein deposit, amethyst crystal of spectacular size were obtained. The development of the deposit with wide-spread sales and distribution of specimens revitalized interest in amethyst in the region (Sinkankas, 1976; Garland, 1994). The interest and activity in amethyst deposits in the Thunder Bay area led to the proclamation in 1975 designating amethyst as Ontario’s provincial gemstone (Patterson 1985). A comprehensive report on amethyst deposits and mining activity in the Thunder Bay area was completed by Garland (1994). The interest and activity in amethyst deposits in the Thunder Bay area led to the Mineral Emblem Act in 1975 designating amethyst as Ontario’s provincial Mineral Emblem (Ontario, 1990; Patterson, 1985), with the 50th anniversary taking place in 2025. There are currently 15 amethyst quarries authorized to produce under the Ontario Ministry of Nature Resources Aggregate Resources Act within two areas northeast of Thunder Bay (Campbell et al. 2024). Twelve of these authorized amethyst extraction sites are in McTavish Township and are accessible from Highway 11-17. The other three authorized quarries are located in the Tartan Lake Area (north of MacGregor Township) in an area that is accessed via the Magone Lake Road from Highway 527. Four quarries operate as tourist attractions that are open to the public on a seasonal basis. A listing of these amethyst quarries, including information about their products and services (where available), is provided in Table 1 (Campbell et al., 2024). Geology Of Amethyst Mine Panorama (Thunder Bay Amethyst Mine) Geologic Setting The geological setting of the mine is complex, as an Archean and a Proterozoic record are preserved in the area. This record has been recently reviewed by Sutcliffe (1991) with an update by Addison et al. (2010) and will not be repeated in detail here. The Amethyst Mine Panorama (Thunder Bay Amethyst Mine) is hosted in the Archean Hilma Lake granite of McCrank et al. (1981). This pluton lies on the boundary of the Quetico Subprovince and the Wawa Subprovince, with typical greenstone lithologies on its southern margin and gneissic metasedimentary rocks on the northern margin. The Hilma Lake granite in the vicinity of the mine consists predominantly of monzonite, with compositional variation along the trend monzonitequartz monzonite-granite-granodiorite and pegmatite and pegmatitic textural variants (Jennings, 1985). Jennings’ study indicates that monzonite had been cut first by granodiorite, then by pegmatite, with some metasomatic alteration of early monzonite toward granodioritic composition. At the Greenwich Lake uranium occurrence, a vein-type occurrence located 10 km to the northwest, Franklin (1978) noted the presence of quartz monzonitic pegmatites containing 60-100 ppm U in the form of uraninite. As these pegmatites are apparently comagmatic with the Hilma Lake granite, its uranium-rich character is likely a general feature. The Proterozoic rocks were deposited on the eroded Archean surface; however, the Animike Group (Gunflint and Rove Formations) is missing in the vicinity of the amethyst mine. As indicated by Franklin et al. (1980), the Mesoproterozoic Sibley Group progressively onlaps Archean terrain in a northerly direction. The Sibley Group is presently absent in the vicinity of the Amethyst Mine Panorama, although its presence as abundant fragments in mineralized breccias within the vein system indicates that these sediments - 128 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Table 1. Amethyst quarries in the Thunder Bay Area authorized to produce under the Aggregate Resources Act (from Campbell et al. 2024) Deposit Name and Ownership Amethyst Mine Panorama Precious Purple Gemstones Ltd. Location (Licence) McTavish Township (622921) Products and Services Tourist attraction (pick-your-own and mine tours), specimens, decorative and landscaping stone, and tumbling stone, jewellery, giftware, carvings, faceted gemstones www.amethystmine.com/ Blue Points Amethyst Mine Jordan Vivian McTavish Township (624926) Tourist attraction (pick-your-own), specimens, decorative stone, aquarium stone www.tripadvisor.ca/Attraction_Reviewg155017-d3334892- ReviewsThe_Blue_Point_Amethyst_MineThunder_Bay_Thunder_Bay_District_Ontario.ht ml (lynswan@lakenet.com – email) Diamond Willow Amethyst Mine Big Pearl, Sward Lake B. Leroux and C. Fayle McTavish Township 3 permitted quarries, (626151, 625922, 626134) Tourist attraction (pick-your-own and mine tours), specimens, decorative and landscaping stone, slabs, tumbling stone, jewellery and giftware www.diamondwillowamethyst.com/ Keetch Quarry / Boulder Creek Amethyst Quarry L. Harasym McTavish Township (77956) Tourist attraction (pick-your-own), specimens https://mininglifeonline.net/company_page_487.html Assiniboia Amethyst Mine P. and T. Smitham McTavish Township (626091) Not open to the public, but may be visited by invitation only. Contact: https://assiniboiaamethystmine.weebly.com/ Bill’s Old Amethyst Mine K. Zytaruk McTavish Township (607322) Not advertised Canadian Shield Amethyst Mine K. Zytaruk McTavish Township (616261) Not advertised Tartan Lake Danbill Mine Auralite 23 Mine and Company Area (20227) Inc. Specimens, polished and tumbled stone, jewellery, tiles and countertop stone www.auralite23canada.com/home.html Gunnard Project M. Noyes and J.A. Gavin McTavish Township (625989) Not advertised Loon Lake Technical Services Quarry Loon Lake Technical Services McTavish Township (625067) Not advertised Tartan Lake Area Purple Haze Mine Auralite 23 Mine and Company (624879) Inc. Specimens, giftware, jewellery, decorative and landscaping stone from former owners at www.purplehazeamethyst.com/. Transferred to new ownership in late 2022. Roll Lake Amethyst Tartan Lake Area Auralite 23 Mine and Company (624838) Inc. McTavish Windy Ridge Amethyst L. Kowtuski Township (625831) Specimens, polished and tumbled stone, jewellery, tiles and countertop stone www.auralite23canada.com/home.html - 129 - Email: windyridge@live.ca �Proceedings of the 72nd ILSG Annual Meeting - Part 2 were present as basement cover during the forming of the deposit. The significance of the Sibley Group is unclear in the face of contradictory evidence concerning its age and depositional setting. Franklin et al. (1980) noted that the Sibley Group isdeposited at the location of a failed arm of an r-r-r triple junction, although they admitted to uncertainty as to the contemporaneity of sedimentation and rifting. Although some features of the Sibley Group are suggestive of a rift-filling deposit, the whole-rock Rb/Sr age of 1339±33 Ma (Franklin, 1978b) is approximately 200 Ma prior to the main stage of rifting of the Midcontinent (Keweenawan) Rift (Van Schmus et al., 1982). Cheadle (1986), however, concluded on the basis of sedimentological studies that the Sibley Group was not deposited in a classical aulocogen, but represents a deposit on a sagging crust preceding rifting. The Sibley Group was more recently dated by U/Pb geochronology in zircons in a basal rhyolite unit at 1537+10/-2 Ma (Davis and Sutcliffe, 1985). This timing makes a relationship with the Midcontinent Rift event unlikely, and Hollings et al. (2004) proposed that the Sibley Basin formed due to effects of a plume track that created an infracratonic basin. by breccias of granitic country rock and Sibley Group sedimentary rocks with large proportions of void space. The brecciated fault was subsequently mineralized by hydrothermal solutions. At least two periods of mineralization occurred, as an early generation of amethyst was clearly brecciated and subsequently coated by a second generation of amethyst. Figure 4 is an illustration of the state of the mine in 1987. At present, the main pit configuration is basically the same but has been deepened. In that year, an extension of the vein system to the east was developed, offset to the north by a few metres strike-slip fault. Jennings (1985) subdivided the mineralization patterns into three basic types: (i) open fracture fillings, (ii) breccias with tectonic and collapse subtypes, and (iii) “honeycomb” veins. Other deposits located at or near the Sibley -Archean unconformity include the Dorion lead -zinc -barite veins (Fig. 3). The ore-depositing solution was considered to be a basinal, connate brine by Franklin and Mitchell (1977), an interpretation supported by the fluid-inclusion studies of Haynes (1988). As illustrated in Figure 3, there is a close spatial relationship between the lead-zinc-barite veins and the amethyst, and both are spatially related to the Sibley-Archean unconformity. Geological features of the mine Amethyst Mine Panorama is located within a firstorder strike-slip fault, which strikes at 90- 100º and dips steeply to the south. This fault is roughly parallel to one 2.1 krn to the south, which strikes east-northeasterly (McIlwaine, 1971) and has a vertical displacement of at least 125 m (Jennings, 1985), forming a major boundary to the Sibley Group’s depositional basin. The strike-slip fault hosting the amethyst deposit is offset by seven first-order strike-slip faults, five of which are illustrated in Figure 4, which strike 162 - 150° and dip vertically producing en echelon, pull-apart structures in the main fault. These structures are filled Figure 3. Local geology and location map of amethyst deposits and lead-zinc-barite deposits, showing the relationship of the former to the margin of the Sibley Group outcrop and the Hilma Lake granite. The location of the producing Thunder Bay Amethyst Mine’s are indicated by stars. Bedrock geology and mineral occurrence locations modified from Ontario Geological Survey (2011; 2026). - 130 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 4. Diagram of the main pit of Amethyst Mine Panorama (Thunder Bay Amethyst Mine). The strike directions of these veins are strongly clustered in two groups, one slightly west of north and parallel to the second stage of strike-slip faulting, and one easterly, parallel to the principal directions of faulting. Open fracture fillings are common in the shallower zones of the deposit where low lithostatic pressure permitted the maintenance of open fissures following faulting. The veins are widest near the edges of collapsed breccias and at the intersections of oblique shears with the main fault zone. Fracture-fill mineralization occurred at the crystal-fluid interface as quartz crystals grew outward from the fracture walls. The crystals formed as parallel to radial growths with long crystal axes oriented perpendicular or subperpendicular to the growth surface. The crystal size invariably increases outward, and outward growth from opposite fractures resulted in an interlocking comb structure of euhedrally terminated crystals. This vein type may also contain vugs up to 2-3 m in diameter with large quartz crystals up to 10-15 cm in prism diameter. Tectonic breccias are here attributed to fault movement, as opposed to brecciation caused by collapse with variable degrees of fluid action. Some breccia fragments are surrounded only by a later portion of the paragenetic sequence, suggesting that multiple fault motion during the mineralizing event has occurred. Breccia fragments of this type are invariably angular and may consist of fragments of earlier deposited vein material, which may have been thermally bleached. Collapse brecciation is not always differentiated from tectonic brecciation, and some collapse breccias have undergone subsequent tectonic brecciation and vice versa. Evidence of collapse brecciation is seen in the occurrence of Sibley Group lithologies not present in the mine area now, together with granite and diabase as breccia fragments. Sibley Group fragments are particularly abundant within channel- or pipe-like structures in which fluid transport and abrasion have produced subangular to subrounded fragments, which have undergone an appreciable degree of sorting. Collapse-breccia fragments are typically coated with successive layers of chalcedony, colorless quartz, and amethyst, producing a cockade structure. Vugs have developed in open space produced in the breccia in which crystals with prism diameters of up to 10 cm have grown. Honeycomb veins are the result of quartz crystallization that has occurred in all directions from small nuclei, usually chalcedony, hematite, or silicified granite fragments, rather than from a fracture wall. The amethyst and quartz are more massive than in the other types of veins, but the growth is chaotic. - 131 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Mineralogy Amethyst and other varieties of quartz. Several varieties of quartz occur in Amethyst Mine Panorama, including colorless quartz; chalcedony; amethyst; the yellowish variety, citrine; and the greenish variety, prasiolite or “greened amethyst”. Smoky quartz has very limited development . The only variety of gemstone interest is amethyst, although the occurrence of the other varieties has aided in establishing the sequence of deposition. A grading system based on estimated intensity of coloration and clarity of specimens is in use at the mine, and this system has also aided in establishing the paragenetic sequence. Thus, the intensity of coloration may be from I (lightest) to IV (darkest) and clarity from a (clear) to f (opaque). Table 2 lists typical paragenetic sequences in an older sequence, which is present as breccia fragments in a younger sequence presently occupying the veins. The prasiolite in stages 4 and 5 of the older sequence appears to be thermally bleached amethyst on the basis of both its appearance and experimental evidence that heat-treated amethyst can be transformed to prasiolite (Lehmann and Bambauer, 1973). In the younger sequence, late-stage variations are noted, particularly as cappings to stage 5. A distinctive variety called “black gem”, a dark, brownish-black amethyst, is apparently characteristic of larger crystals grown in vugs in which iron-enriched, late-stage fluids were trapped. These frequently have final growth zone that contains abundant hematite inclusions, such that recent sales of such material has been called “Thunder Bay red”. It was this material, recovered in the early development of the deposit that led to the notorious statement by Sinkankas (1976, p. 204): “By far most of the amethyst is unsuited for lapidary purposes, with very little being free from flaws and hence useless for faceted gems or even baroques.” Figure 5 illustrating cut and faceted gemstone demonstrates the error in Sinkankas’ statement. The compositions of specimens of amethyst by neutron activation analysis for selected trace elements (Table 3) revealed the presence of subequal concentrations of Fe and Al. As well, low concentrations of Ge were sought based on absorption spectra that indicated its presence. The low Ti concentrations are perhaps related to the spotty occurrence of rutile needles in the amethyst, needles occurring when concentrations are relatively greater. Figure 5. Cut and faceted smoky quartz (top left) and amethyst from Amethyst Mine Panorama (Thunder Bay Amethyst Mine). Photo by S. Kissin. Table 2. Paragenetic sequences observed in the veins of Amethyst Mine Panorama Notes: Variations observed include (i) late-stage greenish and yellowish-amethyst; (ii) late-stage smoky quartz; (iii) discontinuous hematitic and milky quartz capping to crystal terminations; and (iv) development of black gem in crystals, deposited in vugs. - 132 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Table 3. Analyses of r-zones of amethyst for selected trace elements (in ppm; Kissin, 1997) Sample No. Fe Al Ge Ti DZS1* 217 447 0.5 n.d. LZS2 102 393 0.5 0.01 BSS3 273 369 1.0 n.d. TPS4 368 249 0.5 n.d. *DZS1 evidently contains solid inclusions, as high concentrations (in ppm) were noted; e.g. Ta 0.329, W 0.38, Eu 0.349, Sr 89.43, Zr 1.02, Nb 0.13, Ba 2985.26, La 3.85, Ce 0.35, U 0.387. All samples contain small, but detectable quantities of Co, Ni, Ga, Rb, Nb, Zr, Mo, Sn, Sb, Cs, La, Pr, Nd and U. Other non-sulfide minerals. Barite is rare in the veins at the Amethyst Mine Panorama, although it is abundant in other amethyst mines of the district, where it follows the final stage of quartz deposition. It was not observed in the course of the present study, but has been noted in the mine. Calcite is fairly common in thin, monomineralic veins, but was not observed within the amethyst-bearing veins. The genetic link between the calcite veins and amethyst veins, if any, is unclear. Hematite is abundant as minute- (< 0.1 mm diam.) solid inclusions in stage 5 of amethyst deposition and occurs sporadically at other stages of deposition as well. Hematite occasionally occurs as a daughter mineral in fluid inclusions, particularly in stage 5 of crystallization. Rutile occurs as needles that transect the growth zones of the quartz in scattered locations within the mine. The orientations of the needles are apparently random; however, the possibility of crystallographically controlled growth directions has not been considered in detail. Native copper occurs in association with copper and copperiron sulfides. Sulfides The common base-metal sulfides pyrite, chalcopyrite, galena, and sphalerite occur in small amounts throughout the vein succession and as veinlets and replacement bodies in altered granitic wall rock. Copper -iron sulfides, however, are predominant, and a sequence of the minerals cuprite-native copperchalcocite-covellite associated with hematite and pyrite was documented by McArthur et al. (1993). The copper -iron sulfides exhibit typical replacement textures (atoll structures, core-and-rim relationships) in occurrences both in amethyst growth stages and in wall rock. The assemblages bornite+pyrite and chalcopyrite+pyrite and chalcopyrite+pyrite occur in wall rock only; however, spatial relations of wallrock sulfides to the veins do not reveal any pattern, owing in part to their scarcity. Malachite is present as a supergene product derived from these hypogene copper minerals. Wall-rock alteration mineralogy. Hematitization, chloritization, and kaolinitization are prominent in envelopes surrounding the veins within zones of brecciated granite; however, the alteration extends only a few centimetres into the granites outside of the zone of brecciation. Intense hematitization occurs fairly generally in altered rock nearest the amethyst veins. The strongly hematitized zone is generally only a few centimetres thick, but weaker hematitization is notable throughout the altered zone. Outward from the hematized zone is an irregular zone of highly chloritized rock ranging from a few to a few tens of centimetres thick. Sometimes associated with the chloritization is diffuse epidotization, which produced a pistachio green tint over zones up to a metre wide. Kaolinitization is widespread and pervasive through the breccia zone, imparting a chalky, white appearance to relict feldspars. Other clay minerals, e.g., montmorillonite and illite, may also be present; however, they have not been sought in a detailed examination. The pervasive kaolinitization has allowed weathering to penetrate into the brecciated zone, resulting in a soft and loosely aggregated matrix in which the near-surface exposures of the amethyst are contained. The nature of this matrix has enabled a good deal of the amethyst to be mined with a minimum of blasting. The hematite-chlorite-epidote alteration assemblages in the presence of ubiquitous quartz are characteristic of the propylitic alteration typical in many hydrothermal ore deposits. The kaolinite and other clay minerals are characteristic of the argillic - 133 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 alteration of hydrothermal ore deposits. The two alteration types are analogous at least in their relative timing to early peripheral propylitic alteration, which is overprinted by argillic alteration stemming from downward-infiltrating meteoric water. Genesis of the deposit The genesis of the deposits of the Amethyst Mine Panorama were discussed in detail by McArthur et al. (1993) in the light of evidence obtained in their study. The conclusions of their study are given below; however, for details of the evidence, their paper should be consulted. Genetic speculations on the Amethyst Mine Panorama are hampered at the outset by questions as to the timing of amethyst deposition, as discussed in the Introduction. The spatial and geochemical affinities of the amethyst deposits with the Dorion lead-zinc-barite veins and the relationships of both to the depositional margin of the Sibley Group sediments suggest that all three are interrelated. Franklin and Mitchell (1977) proposed that the lead -zinc -barite veins formed when, during diagenesis and settling of the Sibley Group sediments, metal-bearing brines were formed when expelled connate waters mobilized metals from the Sibley Group sediments and(or) weathered granitic basement rocks below the Archean-Proterozoic unconformity. The solutions thus formed would have hypothetically migrated through the basal Pass Lake Formation aquifer to escape at basin-marginal faults. Precipitation of sulfide, carried in chloride- and sulfatebearing solution, occurred because of mixing of the relatively oxidized solution with H2S gas trapped at the Pass Lake Formation pinch-out. The amethyst deposits seem to be a variant of the lead-zinc-barite type of deposit in which the temperature was lower than that of the sulfide-rich lead-zinc-barite veins. The initially oxidizing to later reducing character of the solution is similar to that proposed for the lead-zinc-barite veins, but the relation to Pass Lake Formation pinch-outs is not present in most amethyst deposits. Rather, the amethyst deposits are generally hosted in granitic basement often with no Sibley Group sediments present. The amethyst deposits are richer in dissolved silica, having gained this component through the kaolinitization of feldspar during hydrothermal alteration of granitic country rock. As the amethyst deposits formed near the present or former unconformity with the Sibley Group, local reduction of the solution would have tended to occur as H2S was released during thermal breakdown of organic matter in the sediments. The quantity of sulfides precipitated would have been limited not only by the relatively small amount of H2S produced but also by the lower metal content of the solutions as compared with those depositing the Dorion lead-zinc-barite veins. The latter characteristic is inferred by a comparison of the results of this study with those of Haynes (1988) on the Dorion lead-zinc-barite veins. He found that fluid inclusions from these deposits are NaC1-CaC12H2O type on the basis of microthermometry and direct analysis of decrepitates. However, the fluid inclusions depositing sulfides are significantly more saline than those at the Amethyst Mine Panorama in that they contain daughter salts. The more saline and higher temperature (105-203°C) fluid inclusions indicate that solutions that they represent would have had a better metal carrying capacity as chloride complexes. The similarity of the solution components to those at Amethyst Mine Panorama lends support to the idea that the same event formed both types of deposits. The solutions depositing amethyst would have been cooler and less saline variants of those that formed the lead-zinc-barite veins. If the two types of deposit are genetically linked, both suffer from the problem of lack of knowledge of the timing of ore deposition. The maximum age of both is 1339 Ma, the whole rock Rb/Sr age of the Sibley Group (Franklin, 1978b), as both types of veins cut Sibley Group rocks and contain breccia fragments of them. Franklin and Mitchell (1977) did not suggest a specific timing for formation of the Dorion lead-zinc-barite veins; however, their suggested mechanisms for creation of the deposit favor a timing soon after the deposition of the Sibley Group sediments. The expulsion of pore water called upon would presumably occur during late diagenesis. However, as there is no evidence to suggest that the Sibley Group sediments have ever been deeply buried, the source of heat is a problem. If the timing of deposition were close to the formation of the Sibley depositional basin, it is possible that a thermal anomaly, perhaps augmented by seismic pumping, in the lower crust was responsible for both phenomena. Haynes (1988) suggested that the Dorion leadzinc-barite veins formed either in the environment of Keweenawan rifting or later, possibly in the Paleozoic. There is no geological evidence for activity in the Paleozoic in the western Lake Superior region, and the style of mineralization associated with Keweenawan - 134 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 events is different (silver deposits associated in part with Ni-Co arsenides; Franklin et al. 1986). Our preferred hypothesis is that the lead-zinc-barite veins and amethyst veins are associated with the timing of formation of and deposition in the Sibley basin. We, therefore, believe that these deposits are distinct from silver deposits in the Thunder Bay area and formed at a somewhat earlier time. The timing is, however, not at all certain. An attempt was made to directly date amethyst deposition by U/Pb age determinations on rutile needle inclusions in amethyst (Heaman and Easton, 2006). An age of 887±40 Ma with 68.6% discordance was determined on a very small sample with low uranium content. The authors indicated that these results should be viewed with caution as a large lead correction was needed. This age does not coincide with any known geological events in the area. As well, an attempt was made to date the cross-cutting diabase dikes, but was unable to yield any results. Summary Field and laboratory studies of the Amethyst Mine Panorama reveal the following: (3) Sulfide minerals including pyrite, chalcopyrite, galena, and sphalerite accompany amethyst deposition as small mineral inclusions and occur, as well, as veinlets and replacement bodies in altered granitic wall rock. Copper and copper-iron sulfides are most abundant and, together with native copper and cuprite, Eh-pH relationships indicate that the solutions forming the deposit were initially rather oxidizing and weakly acidic. In the course of crystallization, the solution became more reducing and slightly more acidic. (4) Fluid-inclusion studies indicate that in the younger sequence of quartz deposition, homogenization temperatures range from 146.5 to 114.7°C (mean 132.1°C) as contrasted with 91.2-40.9°C (mean 68.4°C) for amethyst. Eutectic temperatures of frozen inclusions indicate that the solution was of the NaClCaCl-H2O system, with possible concentration of an additional halide salt component in late-stage fluids. Few inclusions contain daughter minerals, and those found are hematite and sphalerite in late-stage fluids. Final melting temperatures indicate a trend of decreasing salinity in later growth stages. (5) Oxygen isotopic determinations on quartz indicate a range of δ180 outside that of juvenile (1) The vein system hosting amethyst deposits was formed by mineralization of an east-west-striking, waters and end-member basinal brines. Progressive steeply dipping strike-slip fault, opened into en mixing of basinal brine with local meteoric water echelon pull-apart structures by a series of later strike- is suggested. slip faults, also dipping steeply and intersecting the (6) Sulfur isotopic analyses of pyrite yield δ34S first-formed fault at high angles. Much open space of -0.4 to 0.6 ‰ and -1.4 ‰ in chalcopyrite. These with brecciated and vuggy textures resulted. Breccia volumes are consistent with derivation from H S 2 fragments include granitic host rock and Sibley Group gas liberated by thermal action protection on sedimentary rocks, implying that the latter were present organic material involving iron. The values are as a thin cover at the time of mineralization, although similar to those of the sulfur contained in sulfides they are erosionally removed from the mine area at in the Dorion lead-zinc-barite veins. present. At least one early generation of amethyst is included as breccia fragments, indicating that fault movement continued during mineralization. (2) At least two phases of amethyst crystallization separated by a period of brecciation are present. The older sequence contains five stages of quartz growth, the latter two of which were originally amethyst, but were thermally bleached to prasiolite by the influx of hot solutions that deposited the younger sequence of quartz. The younger sequence contains five and occasionally six stages of deposition, beginning with a stage of chalcedony and a stage of colorless quartz, followed by amethyst. Both sequences of deposition are traceable throughout the mine. (7) The presence Sibley breccia fragments cemented by quartz indicates that the veins cannot be older than 1339 Ma, the Rb/Sr age of the unit. However, a younger limit cannot be established at present. (8) On grounds of similarity in geological setting, proximity, composition of the ore-depositing solution, and sulfur isotopic composition, the amethyst veins are believed to be genetically related to the Dorion lead-zinc-barite veins. Both are believed to have been formed by solutions expelled and mobilized during diagenesis and compaction of the Sibley Group. The lead-zinc-barite veins formed in fractures at or near the margin of the Sibley depositional basin from solutions that were both hotter and more saline than those - 135 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 depositing amethyst. Amethyst-depositing solutions travelled longer distances in granitic basement, dissolving silica by alteration of feldspar. Although the amethyst-depositing solutions probably carried less metal as chloride complexes than did the solutions forming the lead-zinc-barite veins, less H2S at the site of deposition was probably the most significant factor causing a low sulfide content in the amethyst veins. (9) The temperature conditions under which amethyst forms appear to have a high temperature limit; at the Amethyst Mine Panorama this limit is no higher than approximately 115°C and may be as low as approximately 90°C. Temperatures as high as approximately 145°C but possibly as low as 115°C may be sufficient to thermally bleach earlier generations of amethyst in the influx of hot solutions. However, this theory of thermal bleaching has been recently criticized by Herbert and Rossman (2008), who attributed the development of greenish-grey to greenish quartz to the presence of H2O in the crystal. Our work (Klarner and Kissin, 201l) confirms the presence of water in IR absorption spectra; however, the water is largely contained in fluid inclusions, which are abundant and of secondary origin. Use of the highly focus beam of an FTIR microscope has shown that molecular water is of low and nearly identical concentration in both amethyst and “greened amethyst”. Experiments by Goetz (2014) demonstrated that heating at 250ºC for extended periods did not result in bleaching of amethyst, disproving that the 145ºC temperature caused bleaching of amethyst. This problem is unresolved at present. Geology of the Amethyst Mine Diamond Willow Unlike the years of extensive research undertaken at Amethyst Mine Panorama, the other known amethyst deposits in the Thunder Bay region are not well studied and with most information available being from Garland (1994) The original Diamond Willow Amethyst Mine was staked by Gunnard Noyes, in the 1960s with the mine initially operating in the 1970s. Following Gunnard’s passing in 1988, the mining leases were split into two parcels per inheritance and turning the original mine into the current Diamond Willow and Blue Points Amethyst Mines, owned by a son and daughter, respectively. The Diamond Willow Amethyst Mine operated until 2007 and was subsequently closed until 2015 (Garland, 1994). The currently producing Blue Points Amethyst Mine is the eastern extension of the original Diamond Willow mine and operates two and three-quarters of the four pits situated along the breccia zone (Fig. 6). The centre pit is the original and the largest, almost 60 m long and 4 m deep. A fence divides the pit between the two mines. The current Diamond Willow Amethyst Mine; the western extension of the original namesake mine site, operates one and one quarter of the four pits situated along this breccia zone (Fig. 7; Garland, 1994). This mineralized and well developed breccia zone occupies a vertically dipping fault zone, trending approximately 090° and extends for almost a kilometre. The fault separates Sibley Group conglomerates of the Pass Lake Formation from Sibley Group mudstone of the Rossport Formation (Garland, 1994). The current Diamond Willow Amethyst Mine is located at the western end of this fault/breccia zone, separating the Rossport Formation mudstones on the south from the Pass Lake Formation conglomerates on the north side. Both the mudstone and the conglomerate are well-layered, giving them a blocky appearance (Garland, 1994). The breccia zone varies from 1 to 5 m wide, and is characterized by a quartz­rich core and fragments of wall-rock material. In general, the fragment density increases away from the core, but is always matrix supported, the fragments are angular and representative of the wall rocks. Within the breccia, amethyst filled vugs can attain sizes of over 1 m and are lined with large, dark purple crystal points up to approximately 7.5 cm in diameter. The vugs also tend to be filled with a dense red clay; fault gouge, consisting of finely ground quartz, feldspar, chlorite, and biotite (Vos, 1982; Patterson, 1985; Garland, 1994). which must be removed in order to mine the amethyst. Light violet to a very dark, nearly black purple amethyst forms an extensive druse covering along the south wall, crystallizing between the mudstone and the breccia. The crystal points in this druse tend to be small, but are very well-formed, yielding excellent mineral specimens. Like Amethyst Mine Panorama, the amethyst crystals are sometimes coated with a layer of reddish brown hematite. Galena occurs as seams of crystals 1 cm in size, within the quartz at the west end of the exposed breccia zone, chalcopyrite-rich zones - 136 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Figure 6. Plan view of the Blue Points amethyst mine. Figure 7. Plan view of the Diamond Willow amethyst mine, refer to Figure 6 for legend. are associated with rusty stained or clear quartz crystals (Vos, 182; Garland, 1994). - 137 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Road Log Lakehead University to Amethyst Mine Panorama and Diamond Willow Amethyst Mine Leaving Lakehead University, we will follow the portion of the Trans-Canada Highway 11-17 which is the Thunder Bay Expressway. The flat terrain is the remnant of the bottom of the Nipissing stage of ancestral Lake Superior, and proceeding northeasterly, we pass upward through strandlines of the receding Pleistocene lake. Lakehead University itself is underlain by the Gunflint Formation at or near the top of the unit. Shaly rocks near the top of the formation are exposed in the bed of the McIntyre River that flows through the campus; however, in recent years blocks of rock containing the Sudbury ejecta debrisite were excavated during construction of new student residences. These placed in various places around the campus as ornamentation or barriers to vehicular traffic. Continuing, outcrops of a Logan sill diabase are exposed on the left side of the expressway. These sills form the caps of the prominent mesas south of town and underlie the high ground in the northern section of Thunder Bay, formerly the city of Port Arthur. Passing the junction of Red River Road (Highway 102), the expressway is on a level stretch marking the top of a Logan sill. The expressway then passes downhill to the Current River. In proceeding downhill outcrops of Logan sill diabase, Gunflint shale and Gunflint carbonate are successively exposed. The carbonate is ankeritic and is oxidized to yellowish orange. Climbing uphill from the Current River bridge, the highway is again cutting into diabase sill. A fault trends along the highway offsetting the sill on opposite sides of the highway. A few hundred metres farther along the highway, the sill is dropped downward by a fault trending perpendicularly to the highway. Recent work has shown that this sill, known locally as the Terry Fox sill, is a Nipigon sill (Magnus and Kissin 2010). Nipigon sills, which occur from here northeasterly to the Lake Nipigon area, are somewhat younger than Logan sills and can be distinguished on the basis of their trace element composition. Proceeding downhill and rounding a curve to the left, there is a high bluff on the left capped by a prominent diabase sill. The sill has intruded the top of the Gunflint Formation and the overlying Sudbury debrisite layer, which is capped by a thin remnant of Rove Formation shale. This is the only outcrop known in the Thunder Bay area that contains the complete debrisite layer. The east end of this outcrop is bounded by a fault that dropped down the section. Continuing onward, high ground on both sides of the highway are capped by sills; the sill on the right was extensively quarried for railway bed ballast and large stone for construction of the breakwall in the harbor. After the junction with Highway 527, the highway climbs the hill locally known as KOA hill. Prior to a widening of the highway about a decade ago, the angular unconformity between the Gunflint Formation and steeply dipping Archean metavolcanics was exposed on the left of the highway. The hill is formed by the outcrop of the Mackenzie granite, an unmetamorphosed and undeformed, late Archean pluton. The highway continues on top the of granite, which contains occasional roof pendants of Archean metavolcanics. After crossing the Mackenzie River sparse outcrops of granite are replaced by poorly exposed Gunflint Formation until just past the junction with Highway 587. Here, well-bedded red-stained carbonates of the Gunflint Formation crop out beside the highway. Passing onward to the East Loon Road, turn left onto the road, then right on Bass Lake Road. Continue to the turn off on the right to the private road to the mine. Proceeding along the mine road, it climbs steeply up from the Sibley basin onto the Archean Hilma Lake granite, ascending along a border fault surface. At the top of the grade, there is a chance to view Lake Superior with Black Bay, the Black Bay Peninsula and the Sibley Peninsula, clear weather permitting. A few more kilometres brings the road to the mine. To get to the Diamond Willow Mine, head back to Highway 11-17, and turn east towards Nipigon. Travel for approximately 13.4 km and turn left onto 5 Rd S, then make a right and drive to 5 Rd N,, crossing the railbed and make a left onto a private dirt road. Continue on this road staying right for 2.56 km, until a “Y” junction is reached and stay left until you reach the Diamond Willow Amethyst Mine parking area. - 138 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Amethyst Mine Tours amethystine color in quartz. Mineralogical Record, v. 20, p. 365-367. Note: Safety boots or shoes recommended. No sandals or open-toed shoes. Cox, R.T., 1977, Optical absorption of the d4 ion Fe4+ in pleochroic amethyst quartz, Journal of Physics C: Solid State Physics, v. 10, p. 4631-4643. The tours will pass through the operating mining areas, which is not available to ordinary tourists. No collecting is allowed in these areas After visiting the mining area, there will be an opportunity to look for specimens in a designated collecting area. The charge for specimens is by weight. Hammering or chiseling is not permitted in Amethyst Mine Panorama’s collecting area, hammering and chiseling are only permitted at Diamond Willow Amethyst Mine; however, only hammers up to 2 lb. max, are permitted and absolutely no sledge hammers and safety glasses must be worn when using hammers or tools while collecting. Specimens are also for sale in the shops. Davis, D.W., and Sutcliffe, R.H., 1985, U-Pb ages from the Nipigon Plate and northern Lake Superior. Geological Society of America Bulletin, v. 96, p. 1572-1579. References Addison, W.D., Brumpton, G.R, Davis, D.W., Fralick, P.W., and Kissin, S.A., 2010, Debrisites from the Sudbury impact event in Ontario,north of Lake Superior, and a new age constraint: Are they base-surge deposits or tsunami deposits? In W.U.Reimold, and R.L. Gibson, eds., Large Meteorite Impacts and Planetary Evolution IV: Geological Society of America Special Paper 465, p. 245-268. Deer, W.A., Howie, R.A., and Zussman, J. 1963, RockForming Minerals,Vol. 4 Framework Silicates. John Wiley and Sons, Inc., New York, 435 p. Franklin, J.M. 1978a, Uranium mineralization in the Nipigon area,Thunder Bay District, Ontario. in Current Research, Part A. Geological Survey of Canada, Paper 78-lA, pp. 275-282. Franklin, J.M., 1978b, The Sibley Group, Ontario, in Rubidium strontrium isochron age studies report 2. Edited by R.K. Wanless and W.D. Loveridge. Geological Survey of Canada, Paper 77-14, p. 31-34. Franklin, J.M., and Mitchell, R.H., 1977, Lead-zinc -barite veins of the Dorion area, Thunder Bay District, Ontario. Canadian Journal of Earth Sciences, v. 14, p. 1963-1979. Franklin, J.M., McIlwaine, W.H., Poulsen, K.H., and Wanless, R.K., 1980, Stratigraphy and depositional setting of the Sibley Group, Thunder Bay District, Ontario, Canada. Canadian Journal of Earth Science, v. 17, p. 633-651. Adekeye, J.I.D., and Cohen, A.J., 1986, Correlation of Fe4+ optical anisotropy, Brazil twinning and channels in the basal plane of amethyst quartz, Applied Geochemistry, v. 1, p.153-160. Franklin, J.M., Kissin, S.A., Smyk, M.C., and Scott, S.D., 1986, Silver deposits associated with the Proterozoic rocks of the Thunder Bay District, Ontario. Canadian Journal of Earth Sciences, v. 23, p. 1576-1591. Belleau, Rémi., 1576. Les amours et nouveaux eschanges des pierres précieuses : vertus et proprietez d’icelles ; Discours de la vanité, pris de l’Ecclesiaste ; Eclogues sacrees, prises du Cantique des Cantiques ([Reprod.]) / par Remy Belleau. Published by M. PatissonM. Patisson (Paris). Accessed from BnF Gallica: https:// gallica.bnf.fr/ark:/12148/bpt6k522648/f21.image. Last Accessed on November 14, 2025 Frondel, C. 1962, The System of Mineralogy, 7th edition, Vol. III Silica Minerals. John Wiley & Sons, New York and London, 334 p. Campbell, D.A., Jonsson, J.R.B., Kurcinka, C.E., Hinz, S.L.K., Sabiri, N., Meyer, G., McEachern, A.D. and Smith, A.M. 2024. Report of Activities 2024, Resident Geologist Program, Thunder Bay South Regional Resident Geologist Report: Thunder Bay South District; Ontario Geological Survey, Open File Report 6417, 128p. Cheadle, B.A., 1986, Alluvial-playa sedimentation in the Lower Keweenawan Sibley Group, Thunder Bay District, Ontario. Canadian Journal of Earth Science, v. 23, p. 527-541. Cohen, A.J., 1989, New data on the cause of smoky and Garland, M.I., 1994. Amethyst in the Thunder Bay area. Ontario Geological Survey, Open-file Report 5891, 197 p. Goetz, M.M. 2014. Heating Experiments of Amthyst from Thunder Bay Amethyst Mine. HBSc thesis, Lakehead University, 63 p. Haynes, F.M., 1988, Fluid-inclusion evidence of basinal brines in Archean basement, Thunder Bay Pb-Zn-Ba district, Ontario, Canada. Canadian Journal of Earth Sciences, v. 25, p. 1884-1894. Heaman, L.M., and Easton, R.M., 2006, Preliminary U/ Pb geochronology results: Lake Nipigon Region Geoscience Initiative. Ontario Geological Survey Miscellaneous Release – Data 191, 79 p. Hebert, L.B., and Rossman, G.R., 2008, Greenish quartz from the Thunder Bay Amethyst Mine Panorama, Thunder - 139 - �Proceedings of the 72nd ILSG Annual Meeting - Part 2 Bay, Ontario, Canada. Canadian Mineralogist, v. 46, p. 111-124. Holden, E.F., 1925, The cause of color in smoky quartz and amethyst, American Mineralogist, v. 10, p. 203-252. Hollings, P., Fralick, P., and Kissin, S., 2004, Geochemistry and geodynamic implications of the Mesoproterozoic English Bay granite-rhyolite complex, northwestern Ontario. Canadian Journal of Earth Science, v. 41, p. 1329-1338. Jennings, E.A., 1985, Geology of the Thunder Bay Amethyst Mine and Precious Purple Gemstone claims. Report to Precious Purple Gemstones Ltd., Thunder Bay, Ont., 65 p. Kissin, S.A., 1997, Comprehensive research to colour enhance Canadian amethyst by heat treatment and irradiation. Final Report, Amsearch Colour Project, Northern Ontario Development Agreement SSC File #015SQ-2223440-2-9243, 36 p. and appendix. Klarner, J.M., and Kissin, S.A., 2011, Hydrothermal bleaching of amethyst at the Thunder Bay Amethyst Mine, Ontario. Geological Society of America Annual Meeting, Minneapolis, Paper No. 44-11. Lehmann, G., and Bambauer, H.U., 1973, Quartz crystals and their colors. Angewendtede Chemie International Edition, v. 12, p. 283-291. Magnus, S., and Kissin, S., 2010, Assimilation and petrogenesis in the Navilus and Terry Fox sills, Thunder Bay, Ontario; in Institute on Lake Superior Geology, Proceedings and Abstracts, v. 56, part 1, p. 36-37. McArthur, J.R., Jennings, E.A., Kissin, S.A., and Sherlock, R.L., 1993, Stable-isotope, fluid-inclusion, and mineralogical studies relating to the genesis of amethyst, Thunder Bay Amethyst Mine, Ontario. Canadian Journal of Earth Science, v. 30, p. 19551969. McLaren, A.C., and Pitkethly, D.R., 1982, The twinning microstructure and growth of amethyst quartz. Physics and Chemistry of Minerals, v. 8, p. 128-135. Ontario 1990. Mineral Emblem Act, 1990, c. M.13, s. 1 Ontario Geological Survey. 2011. 1:250 000 scale bedrock geology of Ontario; Ontario Geological Survey, Miscellaneous Release— Data 126 – Revision 1. Ontario Geological Survey, 2026. Ontario Mineral Inventory; Ontario Geological Survey, Ontario Mineral Inventory, online database (March 2026 update). Patterson, G.C., 1985, Amethyst in the Thunder Bay area of Ontario, Canadian Gemologist, V. 6, p. 104-116. Rossman, G.R., 1994, Colored varieties of the silica minerals, in P.J. Heaney, C.T. Prewitt, and G.V. Gibbs, eds., Silica: Physical Behavior, Geochemistry and Materials Applications, Mineralogical Society of America, Reviews in Mineralogy, v. 29, p. 433-467. Sinkankas, J., 1976, Gemstones of North America, Vol, II. D. Van Nostrand Company, Inc., New York, 494 p. Sutcliffe, R.H., 1991, Proterozoic geology of the Lake Superior area in P.C. Thurston, H.R. Williams, R.H. Sutcliffe, and G.M.Stott eds., Geology of Ontario. Ontario Geological Survey, Special Volume 4, Part 1, p. 627-660. Van Schmus, W.R., Green, J.C., and Halls, H.C., 1982, Geochronology of Keweenawan rocks of the Lake Superior region: A summary, in R.J. Wold and W.H. Hinze, eds., Geology and Tectonics of the Lake Superior Basin, Geological Society of America, Memoir 156, p. 165-171. Vos, M.A., Abolins, T., and Smith, V. 1982: Industrial. Minerals of Northern Ontario- Supplement 1, Ontario Geological Survey Open File Report 5388, 344 p. McCrank, G.F.D., Misiura, J.D., and Brown, P.A., 1981, Plutonic rocks in Ontario. Geological Survey of Canada, Paper 80-23, 171 p. - 140 - � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Institute on Lake Superior Geology Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Institute on Lake Superior Geology: Proceedings, 2026 Description An account of the resource Institute on Lake Superior Geology. Thunder Bay, Ontario. May 21-22, 2026. Creator An entity primarily responsible for making the resource Institute on Lake Superior Geology Date A point or period of time associated with an event in the lifecycle of the resource 2026-05-21 Format The file format, physical medium, or dimensions of the resource PDF Language A language of the resource English Type The nature or genre of the resource Text https://digitalcollections.lakeheadu.ca/files/original/0bc4521136a9278823c1da188a7d4f06.jpg 6dec1707263d949bced940078cb7eaac Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource General Archives Description An account of the resource Archival records that don't belong to another listed collection. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Twenty-five boats tied up in Port Arthur for the winter Subject The topic of the resource Nature Transportation Description An account of the resource Sepia-toned photograph of a view of Lake Superior from Port Arthur during the winter. A small pier can be seen in the foreground while some ships and the Sleeping Giant can be seen in the background. Creator An entity primarily responsible for making the resource Rogers Photo Date A point or period of time associated with an event in the lifecycle of the resource 1913 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource JPG Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context General Archives - 95u Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada - Ontario - Port Arthur Canada - Ontario - Thunder Bay https://digitalcollections.lakeheadu.ca/files/original/bd4fd0a898e18f7b3aa43031cd736f9f.jpg 8c73b87a0dd0eb4aa516cfc1cfff3b59 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource General Archives Description An account of the resource Archival records that don't belong to another listed collection. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Group of unknown children Subject The topic of the resource People Description An account of the resource Black and white photograph of a group of unknown children sitting on large rocks. There are five girls and two boys in the photo. 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Title A name given to the resource Board of directors of the Thunder Bay Finnish Historical Society Subject The topic of the resource People Organizations Description An account of the resource Black and white photograph of the board of directors for the Thunder Bay Finnish Historical Society. Individuals have been identified from top left to bottom right as follows: 1. Mrs. Sylvia Niemila 2. Alex Langila 3. Mrs. Sylvia Syrja 4. Mrs. Esther Lahtinen 5. Peter Wanson 6. Mrs. Tyyne Karttunen 7. John Niemila 8. Emil Maki 9. Mrs. Aili Laakso 10. Mrs. Alma Maki 11. Matti Puustinen Format The file format, physical medium, or dimensions of the resource JPG Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context General Archives - 95q Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada - Ontario - Thunder Bay https://digitalcollections.lakeheadu.ca/files/original/7538f913a2bb6fd217d25d0ebf422fe7.jpg 0d3b540d51fc7ba444e16a901d279114 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource General Archives Description An account of the resource Archival records that don't belong to another listed collection. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Directors of the Finnish Temperance Society Subject The topic of the resource People Organizations Description An account of the resource Black and white photograph of the directors of the Finnish Temperance Society. Also known as the Uusi Yritys or New Attempt Temperance Society, this organization was formed by Finnish Immigrants in early Port Arthur. Along with Finnish-American Workers’ League Imatra #9 they helped construct the Finnish Labour Temple. Individual members have been identified from top left to bottom right as: 1. John Koivu 2. Otto Hieno 3. Axel Forstrom 4. Karl Nyman 5. John Hill 6. Alex Langila 7. Mrs. Alex Langila 8. Mrs. J. Hill 9. Mrs. Aino Kantola 10. Erik Saarikoski 11. Mrs. E. Krockbeck Date A point or period of time associated with an event in the lifecycle of the resource 1902 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource JPG Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context General Archives - 95p Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada - Ontario - Port Arthur Canada - Ontario - Thunder Bay https://digitalcollections.lakeheadu.ca/files/original/d3fa16af08a36298857646dbdecf36ed.jpg a2cc87f34d2bbbc52eb141fe49e835c2 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource General Archives Description An account of the resource Archival records that don't belong to another listed collection. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Ojibway birch bark canoe Subject The topic of the resource Transportation Description An account of the resource A postcard with a black and white photograph of two Indigenous men standing beside an Ojibway birch bark canoe on the front. These masterfully engineered canoes were the principal means of travel for Indigenous peoples of this region, and for explorers and settlers for many years as well. 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Title A name given to the resource First passenger train Prince Rupert Subject The topic of the resource Transportation Description An account of the resource Post card with a black and white image of the first passenger train coming out of Prince Rupert. This train originally ran the first 100 miles from Prince Rupert to Kitselas. Date A point or period of time associated with an event in the lifecycle of the resource 1911-06-14 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource JPG Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context General Archives - 95l Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada - British Columbia - Prince Rupert https://digitalcollections.lakeheadu.ca/files/original/d0267a289688d770e21665e7dab1aa60.jpg f59adeabfb913de313a807addfe1ef36 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource General Archives Description An account of the resource Archival records that don't belong to another listed collection. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Mining machine Subject The topic of the resource Business and Industry Description An account of the resource Black and white photograph of a group of men gathered around a mining machine. Format The file format, physical medium, or dimensions of the resource JPG Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context General Archives - 95k