233 10 13080 https://digitalcollections.lakeheadu.ca/files/original/5/2838/150908-002a.jpg 1eec2e0c6894e58b93aed06be601f903 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 Portrait of two women and a man holding the reins of a horse- drawn buggy and carriage Subject The topic of the resource Mining People Description An account of the resource Photograph of a man wearing a bowler hat, holding the reins of the horse. One woman, not facing the camera is seated beside him and the other woman is in the back seat with a blanket across her knees. A kerosene lamp is attached to the front left seat of the carriage Date A point or period of time associated with an event in the lifecycle of the resource circa 1900s Contributor An entity responsible for making contributions to the resource Donated by Mrs. Cochran Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource Photograph Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context A0014#136,Z/13, scan #150908-002 1900s buggy horse reins https://digitalcollections.lakeheadu.ca/files/original/4/2844/img20201023_15054915_[2].jpg fee0451275dbbcc0e9152fc09394a0bd 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 Technical Institute, Ontario Department of Education Subject The topic of the resource Schools Universities Architecture Description An account of the resource Black and white photograph of Lakehead Technical Institute, 100 Cumberland North Street, Port Arthur, Ontario. This building served as a temporary location and was built from several army huts that were dismantled and brought to the Lakehead. Date A point or period of time associated with an event in the lifecycle of the resource 1947 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource Photograph Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context Archive u100 P/161 scan# img20201023_15054915 100 North Cumberland 1947 Lakehead Technical Institute Schools https://digitalcollections.lakeheadu.ca/files/original/a3e01eb0d76ef433a45d2f049d1e31cc.jpg f4b62f4d6568cfc33240087c0f911743 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 Thunder Bay Finnish Canadian Historical Society Collection Subject The topic of the resource Finnish-Canadians Life in Thunder Bay Description An account of the resource Photographs collected by the Thunder Bay Finnish Canadian Historical Society from a wide range of collectors, documenting Finnish immigration to and life in Thunder Bay. Creator An entity primarily responsible for making the resource Thunder Bay Finnish Canadian Historical Society Publisher An entity responsible for making the resource available Lakehead University Library 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 Nahjus Athletic Club Subject The topic of the resource Sports Description An account of the resource Sports (Nahjus): Nahjus Athletic Club, 1927. Date A point or period of time associated with an event in the lifecycle of the resource 1927 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource JPG Identifier An unambiguous reference to the resource within a given context MG8_D333Hi296 scan#010610-015 Type The nature or genre of the resource Still image 1927 Ariel Lehto Armas Randen group photograph Manu Nalli Martha Lake Nahjus Athletic Club Ollie Kantola Peggy Tuomi Santeri Anttila sports William Arnberg https://digitalcollections.lakeheadu.ca/files/original/e9b5941fbd97c3cdd095fd60192d996e.jpg 6761c3d19cae7550688caeb1df659aee https://digitalcollections.lakeheadu.ca/files/original/85882ee3edb0ca322ff493222212d7ab.jpg c5b14afd40e5a0bea6bb4efe42db6891 https://digitalcollections.lakeheadu.ca/files/original/45188918c3e48f825a6c8075e5d70c48.jpg 92054f50b2b5f0e252df6fc85e7c41cc 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 Thunder Bay Finnish Canadian Historical Society Collection Subject The topic of the resource Finnish-Canadians Life in Thunder Bay Description An account of the resource Photographs collected by the Thunder Bay Finnish Canadian Historical Society from a wide range of collectors, documenting Finnish immigration to and life in Thunder Bay. Creator An entity primarily responsible for making the resource Thunder Bay Finnish Canadian Historical Society Publisher An entity responsible for making the resource available Lakehead University Library 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 Port Arthur Jyry Athletic Club wrestlers Subject The topic of the resource Sports Description An account of the resource Sports (Jyry): Port Arthur Jyry Athletic Club wrestlers group photo, 1910s. Coached by A. Oja at Big Finn Hall. Donor: L. Sipila. 3 copies. 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 scan# TBFCHS-H247 MG8_D227Hi247 MG8_D227Hi247a MG8_D227Hi247b 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 Canada - Ontario - Port Arthur 1910 Alex Sipila Alfons Oja Jyry Athletic Club Port Arthur Wrestling https://digitalcollections.lakeheadu.ca/files/original/77c67d8d4daf4f3748f8aa2cb5bc937e.jpg 3f65384663ff89bd0ab4a9764f6b16f5 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 Aerial view of residences Subject The topic of the resource University Life Architecture Description An account of the resource Aerial photograph of residences Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource photograph Type The nature or genre of the resource still image Identifier An unambiguous reference to the resource within a given context UG6-AP-I-78 scan #061107-001 Lakehead University Residences https://digitalcollections.lakeheadu.ca/files/original/179540342aba69098072cc01f00f12e9.JPG d6220938c3f39b94f2a12433b538a3d0 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 men's basketball team versus Yugoslavia, 1970 Subject The topic of the resource Sports University Life Description An account of the resource Black and white photograph of Lakehead University men's basketball game versus a team from Yugoslavia. The game is played at a packed C.J. Saunders Fieldhouse. Final score LU 62, Yugoslavia 60 Date A point or period of time associated with an event in the lifecycle of the resource 1970-71 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource Photograph Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context UG6-A-I-128 scan#share1.jpg 1970 1971 Atheltics C. J. Saunders Fieldhouse Lakehead University Athletics Men's Basketball https://digitalcollections.lakeheadu.ca/files/original/618e98f1d0e11ee99a9e64a4d467ce11.JPG c2b1ad69849d3a89bb4f27304ded3df2 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 men's basketball team versus Yugoslavia, 1970 Subject The topic of the resource Sports University Life Description An account of the resource Black and white photograph of Lakehead University men's basketball team versus a team from Yugoslavia. The game is played before a packed C.J. Saunders Fieldhouse. Final score LU 62, Yugoslavia 60 Date A point or period of time associated with an event in the lifecycle of the resource 1970 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource Photograph Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context UG6-A-I-127 scan#img_0003.JPG 1970 Atheltics Basketball C.J. Saunders Fieldhouse Lakehead University Athletics Men's Basketball Yugoslavia https://digitalcollections.lakeheadu.ca/files/original/6c9b6534e39670aa4e43358531605f34.JPG a0c5addca8077fe5f725ae4df6702c1f 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 men's basketball team versus Yugoslavia, 1970-71 Subject The topic of the resource Sports University Life Description An account of the resource Black and white photograph of Lakehead University men's basketball game versus a team from Yugoslavia. The game is played before a packed C.J. Saunders Fieldhouse. Coach Howard Lockhart is in a huddle with a group of his players. There is a banner Welcome Skopje hanging from the upper row of the fieldhouse. The final score was LU 62, Yugoslavia 60 Date A point or period of time associated with an event in the lifecycle of the resource 1970-71 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource Photograph Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context UG6-A-I-126 scan#img_0002.JPG 1970 1971 Athletics C.J. Saunders Fieldhouse Lakehead University Athletics Men's Basketball https://digitalcollections.lakeheadu.ca/files/original/edcbe7992e95de5f185adbde41066d15.JPG 58906acc48e43c550f55554d1acafd74 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 C.J. Saunders Fieldhouse, 1968-69 Subject The topic of the resource Sports University Life Description An account of the resource Black and a white interior photograph of newly constructed C. J. Saunders Fieldhouse. Some athletes are practicing their sport on the basketball court Date A point or period of time associated with an event in the lifecycle of the resource 1968-69 Rights Information about rights held in and over the resource Public domain Format The file format, physical medium, or dimensions of the resource Photograph Type The nature or genre of the resource Still image Identifier An unambiguous reference to the resource within a given context UG6-S-I-1 scan#0001-JPG 1968 1969 Athletics C.J. Saunders Fieldhouse Lakehead University Athletics sports https://digitalcollections.lakeheadu.ca/files/original/c19f5e2236ad99fdefc3662e6dd01909.pdf c1f19976c2cbfb13e24e0f562bf0fccd PDF Text Text �INSTITUTE ON LAKE SUPERIOR GEOLOGY April 1 2, 1955 UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis i4 �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis it,. Institute on Lake Superior Geology April 1 - 2, 1955 PROGRAM 8:1.5 a. April 1, 1955 m. Auditorium, Museum of Natural Eistory Friday - Carl E. Dutton, Chairman U. S. Geological Survey, Madison, Wisconsin Welcome: 1. 2. 3. 11. 9:00 F. E, Berger, Director, Center for Continuation Study J. M. Nolte, Dean of University Extension G. A. Thiel, Chairman, Department of Geology and Mineralogy Harold L. James: Sedimentary fades of iron-formation 10:00 Intermission (Please, no smoking in auditorium) 10:10 David White: 11:10 DiscussIon 12:00 Luncheon Origin of the Biwabik iron-formation, Mesabi Range, Minnesota 1:30 Burton Boyum, Gerald J. Anderson, and Tsu-Ming Han: Progress report on the primary features of the Negaunee iron-formation, Marquette district, Michigan 2:30 DIscussion 3:00 Intermission 3:10 Stanley Tyler: li.:1O Discussion On the origin of the Lake Superior iron ores �UNIVERSITY OF MI1'INESOTA Center for Continuation Study Minneapolie 111 •"titute on Lake Superior Geo1 April 1 - 2, 1955 PROGRAM Friday - April 1, 1955 6:30 p.m. Junior Ballroom, Coffman Memorial Union 0. M. Schwartz, Professor of Geology and Director, Minnesota Geological Survey GEOPHYSI CS IN TEE LA STJPERI OR EEGI ON Gordon Bath, Chairman U. S. Geological Survey Charles E. Jahren: Some magnetic susceptibility measurements on diamond drill cores from the Cuyuna district Edward Thiel: Panel A gravity study of the Lake Superior syncline Discussion: James Baisley, Chief, Geophysical Branch, U. S. Geological Survey, Washington, D.C.; Harold Mooney, Assistant Professor of Geophysics, University of Minnesota; George Woollard, Professor of Geophysics, University of Wisconsin; Lloyal 0. Bacon, Assistant Professor of Geophysics, Michigan Institute of Mining and Technology, Houghton, Michigan; and others. �UMEVERSITY OF MINNESOTA Center for Continuation Study Minneapolis 11i April Superior Geology Institute on Lake 1 - 2, 1955 PR0RAM Saturday Morning - April 2, 1955 9:00 a.m. Auditorium, Museum of Natural History Carl E. Dutton and S. S. C-oldich, Co-Chairmen (10-is minutes are allowed for presentation; 5 minutes for discussion) 1. Robert G. Schmidt: Stratigraphy in the central part of the Cuyuna district, Minnes eta 2. 3. I. Justin Zimi, Gerald L. Brooks, Theodore Engel, and Richard Hagni: Studies of stratified rocks occurring below the Huronian succession in the Marquette district, Michigan J. F. Wolff, Sr.: N. King Huber: Summary of the sub-divisional correlation of the Middle Huronian iron formations of the Lake Superior district Environmental control of sedimentary iron minerals 3. Henry Lepp: 6. L. C. Kilburn and HIID.B. Wilson: 7. Alan T. Broderick: 8. Howard Evans: 9. Joseph P. Dobeli: J. E. Dryden: Nagnetite, maghemite, hematite Pyrrhotite iron formations Some notes on the occurrence of oxidation and soft iron orebodies at considerable depth in the Iron River district, Michigan Color photographic record of drill core Sandstone dikes in Keweenawan lavas A near surface crystalline mass at Manson, Iowa �U1IVERSITY OF MENNESOTA Center for Continuation Study Minneapolis ]A Institute on Lake Superior Geology April 1 - 2, 1955 PROGRAM Saturday 1:00 Afternoon - April p.m. Auditorium, Museum of 2, 1955 Natural History Carl E. Dutton and S. S. Goldich, Co-Chairmen Megesoopic petrofabrics used in dociphering structure 1. James W. Trow: 2. J. M. Neilson and J. P. Dobell: 3. F. M. Swain and N. Prokopovitch: Ii.. James H. Zumberge: Keweenawein felcites of the Beto Grise Bay area Stratigraphy of Minnesota lake deposits Bottom coring in Lake Superior 5. Gerald M. Friecinian: Progress report on the Mamainse "Diabase," Batchawana, Ontario 6. Gerald E. Anderson: The ore minerals of the copper-nickel deposits In the Duluth gabbro 7. Donald H. Yardley: 8. M. P. Walls: Geochemical exploration for nickel and copper In northern Minnesota The work of the Hibbing laboratory of the Division of Land and Minerals �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis Institute on Lake i1i April. 1 — 2, 19% Superior Geology THE ORE MINERALS OF THE COPPER—NICKEL DEPOSITS IN THE DULUTH GABBRO Gerald E. Anderson University of Minnesota, Minneapolis, Minnesota The discovery in 19L1.8 of appreciable amounts of copper and nickel sulfides near the base of the Duluth gabbro south of Ely, Minnesota, has stimulated field exploration and laboratory studies. The present work on the mineralogy of the sulfide mineralization is being done under the auspices of the Minnesota Geological Survey with the aid of a fellowship sponsored by the E J Longyear Company. The principal mineralization discovered to date is restricted to a narrow band in the gabbro near the base. Definite paragenetic relationships have been determined between the rock silicates, the magnetite, and the sulfides, which in order of abundance are chalcopyrite, pyrrhotite, cubanite, pentlandite, violarite, and pyrite—marcasite. types of sulfide assemblages. There appear to be two general In some specimens relatively massive copper sulfides predominate, whereas in others, pyrrhotite and pentlandite are more abundant and interstitial to the silicates. The copper—nickel mineralization is characteristic of most, if not all, large differentiated gabbroic intrusions. Brief consideration is given to some hypotheses to explain the origin of the deposits. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis Th Institute April 1 — cii Lake Superior Geology 2, l9S PROGRESS REPORT ON THE PRIMARY FEATURES OF THE NEGAUNEE IRON—FORMATION, MARQUETTE DISTRICT, MICHIGAN Burton H Boyum, Gerald J. Anderson, and Tsu—Ming Han The Cleveland—Cliffs Iron Company, Ishpeming, Michigan A progress summary is presented describing the primary features of the Negaunee iron—formation of the Marquette District, Michigan. The Negaunee iron—formation is distinctive because of its thickness and uniformity and may be considered as being a single unit, by contrast with other major iron—formations of the Lake Superior region in which two to four members are recognized. The general setting and the position in the Huronian sec- tion are outlined. Nomenclature and historical highlights are reviewed. The subject of total thickness is developed. A specific description of the Negaunee iron—formation is detailed. The lower contact with the Siamo formation •is examined relative to the "inter— bedded argillaceous complex". oolitic zones. Clastic phases are shown, together with Attention is given to the igneous rocks found in the Negaunee iron—formation. Special studies using spectrographic analyses and oil field electric logging are presented. The conclusion is reached that the primary Negaunee formation is remarkably uniform and that local primary features cannot be used as horizon markers for great distances, as these features seldom extend more than one—half to one mile along the strike or dip. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis iii. April 1 — 2, 195 Institute en Lake Superior Geology SOME NOTES ON THE OCCURRENCE OF OXIDATION AND SOFT IRON OREBODIES AT CONSIDERABLE DEPTH IN THE IRON RIVER DISTRICT, MICHIGAN Alan T. Broderick Inland Steel Company, Ishpeming, Michigan The earthy to massive hematite—goethite—limonite orebodies in the Iron River District occur in the oxidized portions of a practically unmetamorphosed chert—side rite iron formation. In the writer's opinion, the structural and mineralogic evidence supports classic theory of origin of these deposits, i.e. that they are the result of the oxidation of siderite, the transportation and deposition of iron and the removal of silica by circulating oxygen—bearing meteoric waters. the There is considerable evidence that the replacement of chert by iron oxides and not the leaching of chert is the major ore—forming process. The circulation has been long held to be artesian. However, since ore has now been found at about 2000 feet vertically below ledge and through oxidation down to nearly 3000 feet, topographic and structural arrangements which coi.d have afforded the necessary hydraulic head have become increasingly improbable. The writer proposes that heat introduced along the major faults as hot water or steam provided the energy which caused the circulation. The heavy cool column of meteoric water in a limb of iron formation cut at depth by one of these warm channels would tend to move downward in the formation and then rise in the heated channel. Once established, such a circulation might be supported by heat from the wall—rocks if the geothermal gradient were steep enough. Laboratory experiments on the solubility of silica suggest that the silica—bearing solutions must have been warm. The tendency of many of the orebodies to lie on structural footwalls of either older or younger rocks indicates that another gravity—controlled mechanism must also have been operative. The writer believes that this is simply that the solutions richest in iron, those which would be the most active in replacing the chert, would also be the heaviest and therefore would follow the bottom of any channel and displace any lighter solutions. This density current principle alone might be the circulation—causing force in shallow structures or in cul—de—sac areas lying below the main thermally—stimulated circulation channels. In some of the Iron River mines, there is evidence of a post—oxidati.n period of mineralization that is quite from the original ore—forming period. In these areas, irregular mineralized zones occur which cross the normal orebodies. These zones contain specularite, barite, rhodochrosite, quartz, pyrite, hausrrianite, magnetite, and traces of chalcopyrite, sphalerite, and pitchblende. These may be the result of a late resurgence of hydrothermal fluid from the same source as that which stimulated the deep meteoric circulation, or it could be a later, completely independent invasion from a new source. Radioactive age determination on traces of pitchblende indicate the latter. distinct �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis 1l Institute nn Lake Superior Geol April 1 — 2, 195S SANDSTONE DIKES IN KEWEENAWAN LAVAS Joseph P Dobell Michigan College of Mining and Technology Houghton, Michigan Sandstone dikes occur in a Keweenawan flow which crops out at Bete Grise Bay on the east side of the Keweenaw Peninsula of Upper Michigan. Three parallel dikes fifteen feet apart were noted. The thickness ranges from an inch to eight inches and the length is from seven to eight hundred. feet. Two of the dikes are a few feet beneath the surface of Lake Superior and the third occurs just above the waterline. The elastic material was injected or wind blown which parallel the Keweenaw fault. The dikes are into open fractures megascopically and rnineralogicafly similar to the Upper Cambrian Jaccbsville sandstone. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis it April 1 — 2, Institute on Lake Superior Geology l9S A NEAR SURFACE CRYSTALLINE MASS AT MANSON, IOWA J. E. Dryden Department of Geology, State University of Iowa, Iowa City, Iowa A near—surface occurrence of crystalline rock has been discovered at Manson, Iowa, 17 miles west of Fort Dodge, Iowa. Water well records indicate that it is a flat—topped elliptial mass with an area of approximately square miles. It has steeply dipping sides and rises to within 90 feet of the surface under a cover of glacial drift. a disturbed area measuring l miles by 2L The mass is surrounded by miles. The rock has been cored to a depth of I90 feet. Megascopically, the core is composed of irregularly alternating light gray gneiss, coarse pink and white feldspar, chioritized breccia and chlorite schist with magnetite. A study of selected thin sections suggests an original syenite gneiss extensively replaced by albite and orthoclase. The entire rock is altered to kaoliriite and breccjated zones are altered to chlorite. The lithology suggests that the mass is of pre—Cainbrian age. The disturbed area contains sediments reported to be Cretaceous in age. A cross section of the area reveals evidence of faulting, but the relationship of the faults to the crystalline structure has not been established at this time. �UNIVERSITY OF 1'ttNNESOTA Center for Continuation Study Minneapolis 14 April 1 — 2, 1955 Lake Superior Geology istitute COLOR PHOTOGRAPHIC RECORD OF DRILL CORE Howard Evans Oliver Iron Mining, Research Laboratory, Duluth, Minnesota The usual method of retaining one—half the drill core for permanent visual record has been supplanted by a color photographic record. The colored photographs, supp1emexted by the core logs have been found adequate for subsequent reference. This was done to dispense with the labor of splitting the core, to overcome the problem of large storage space and to permit all the core to be available for testing purposes. The original cost of the equipment and the continuous cost of maintain— ing the program may seem high, but it is only about one—third the cost of splitting and storing core. At the present time, the photographs from over 300,000 feet of drilling are filed in a space approximately 2' x 4 x 4'. If this record had been kept as split core it would have occupied a building 100' x 120' x 10' high, and this space would allow very little room to work. If storage area is limited some of the core eventually will have to be discarded to make room for new core arriving. With the colored photographic record of the drill core, the filing can continue indefinitely without running out of space. It is also more convenient, when there is a desire to review the core from a drill hole, to be able to quickly select the slide from the file, rather than carry on an extended search for it in a storage house and transport it to the examination site. �UNIVERSITY OF MINNESOTA for Continuation Study Minneapolis 34 Center stitute April 1 — 2, 1955 on Lake Suerior Geology PROGRESS REPORT ON TRE MANAINSE "DIABASEtt, BATCHAWANA, ONIARIO. Gerald N. Friedman Saalt Ste. Marie, Ontario, Canada The Mamainse YtDiabasetl is located about 3 miles north of Sa.tilt Ste. Marie in the District of Algoma within about six miles of the east The area is one of the most rugged in Ontario. shore of Lake Superior. The Mamainse "Diabase" forms a high plateau with an average elevation of about 1600 to lOO feet and is intersected by deep fault— and joint— controlled valleys. The Griffin Lake diabase intrusion, which postdates the Mamainse "Diabase", underlies an area of at least three square miles at the eastern margin of the Mamainse "Diabase" and rises to an elevation of 2100 feet towering about 1400 feet above Lake Superior. The Mamainse "Diabase" is a metadiabase and metabasalt composed of plagioclase (AnA5O) and hornblende with locally abundant epidote and chlorite. Its texture ranges from ophitic and poikilophitic to basaltic; metabasalts of porphyritio texture were noted but are rare. Pillow structures suggest deposition in a submarine environment. A complex series of metamorphosed lavas and sediments, and siliceous iron ore is interbedded with the Maniainse "Diabase" near its northern and southern margins. This complex sequence was overlain by the main mass of the Mamainse "Diabase" prior to folding. The rocks maintain general east—west to N 60°E strike and have a steep dip. Granite dikes locally cut up the "diabase" and interbedded formations and are Ln turn cut by later diabase dikes which are probably equivalent to Moore's Lower Keweenawan. Faults and joints of several generations are irominent and are locally mineralized with cobaltite, chalcopyrite, rite, pyrrhotite, molybdenite, carbonate and quartz veins. The Griffin Lake diabase intrusion is mostly composed of plagio— e (An502) and subcalcic augite (2 V= 35—44°). Quartz and opegnatite are abundantly disseminated through the rocks, secondary nblende is locally prominent and epidote has been noted. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis 14 April 1 — istitute on Lake Superior Geo1o 2, 1955 ENVIRONMENTAL CONTROL OF SEDIMENTARY IRON MINERALS N. King I-tuber U. S. Geological Survey, Iron Mountain, Michigan A recontly developed Eh—pH (th = bility oxidation diagram for hematite, siderite and potential) iron mineral pyrite has been extended to Lude raagnetite through the utilization of free enerr data for these als in addition to the solubility data previously used. Physical— a1 data supports the probability of primary (or diagenetic) bite in sedimentary iron—formations as suggested by field evidence. The chemical environments, as indicated by the Eh—pH stability diagram are sunmarized as follows: Hematite: Requires oxidizing environment, although stable under moderately reducing conditions above pH of approximately 5. Siderite: Stable under intermediate Eh conditions, and apparently only below pH of approximately 6.5. Magnetite: Stable under moderately reducing conditions at pH values of approximately 6 or above. Pyrite: Moderate to strongly reducing environment through normal pH range. �UNIVERSITY OF MINNESOTA Continuation Study Center for Minneapolis hi. nstitute April 1 — on Lake Superior Geology 2, 1955 SOME MAGNETIC SUSCEPTIBILITY MEASUREMENTS ON DUMOND DRILL CORES FROM THE CUYtJNA DISTRICT Charles E • Jahren U. S. Geological Survey, Austin Junior College, Austin, Minnesota Measurements of magnetic susceptibility of 57 cores from diamond drilling in the Cuyuna District were made as part of a geophysical study by the U. S. Geological Survey and the Minnesota Geological Survey. Values of susceptibility are calculated from the readings of an alternating current deviation test bridge, slightly modified from commercial design, and the calculated values are tabulated against footage and generalized geologic logs. Susceptibilities of cores with similar where this seems feasible. readings and from adjacent values are averaged The problems of interpreting scattered core smples, the effects of varying core recovery, the compari son of values from oxidized and unoxidized core discussed. are �UNIVERSITY OF IffNNESOTA Center for Continuation Study Minneapolis 14 stitute on Lake orior Gel April 1 — 2., 1955 SEDIMENTaRY FACIES OF IRON—FORMATION Harold L. James U. S. Geological Survey, Menlo Park, California The sedimentary iron—formations in the Lake Superior region can be divided on the basis of the dominant original iron mineral into four prinsulfide, carbonate, oxide, and silicate. As chemical sedi— cipal facies: raents, these rocks reflect certain aspects of the chemistry of the deposi— tional environxients. The major control, at least for the sulfide, carbonate, and oxide types, was the oxidation potential. The evidence indicates that deposition took place in restricted basins, which were separated from the open sea by thresholds that inhibited free circulation and permitted development of abnormalities in oxidation potential and water composition. The sporadic distribution of metamorphism and of later oxidation permits primary fades on the basis of unoxidized, essentially unnetamorphosed material. The sulfide facies is represented by black slates description of the in which pyrite may make up as much as 40 percent of the rock. The free— carbon content of these rocks typically ranges from 5 to 15 percent, indicating that ultra—stagnant conditions prevailed during deposition. Locally, The carbonate facies the pyritic rocks contain layers of iron—rich carbonate. consists, in its purer form, of interbedded iron—rich carbonate and chert. It is a product of an environment in which oxygen concentration was sufficiently high to destroy most of the organic material but not high enough to facios is found as two permit formation of ferric compounds. principal types, one characterized by magnetite and the other by hematite. The cie Both minerals appear to be of primary origin. The magnetite—banded rock is one of the dominant lithologies in the region; it consists typically of magnetite interlayered with chert, carbcnate, or iron silicate, or combinations of the three. Its mineralogy and association suggest origin under weakly oxidizing to moderately reducing conditions. The hematite—banded rocks consist of finely crystalline hematite interlayered with chert or jasper. Oolitic structure is common. This facies doubtless accumulated in a strongly oxidiz- ing, probably nearshore, environment similar to that in which younger hematitic ironstones such as the Clinton oolite were deposited. The licate faci contains one or more of the hydrous ferrous silicates (greenalite, minnesotate, stilpnomelane, chlorite) as a major constituent. Granule structure, similar to that of glauconite, is typical of some varieties; others are nongranular and finely laminated. The most common association of the silicate rocks is with either carbonate— or magnetite—bearing rocks, which suggests that the optimum conditions for deposition ranged from slightly oxidizing to slightly reducing. AU of these rocks show evidence of post—deposition, pre—lithifica— tion changes (diagenesis), which in general have produced minerals characteristic of one step lower in the oxidation—potential scheme. �UNIVERITY OF ffNNESOTA Center for Continuation Study Minneapolis Institut on Lake Superior ology 14 April 1 — 2, 1955 Harold L. James Page 2 The generalized facies characteristics of the iron—formations in the principal Lake Superior districts are summarized as follows: 1. Mesabi. Most of the Biwabik iron—formation is of the oxide facies, principally magnetite—banded, with a large amount of granular silicate rock. White's study has shown that the oxide—silicate rocks of the main Mesabi grade westward into carbonate and sulfide facies. 2. Ouyuna. Principally silicate and carbonate rocks, verging toward the sulfide facies (which accounts for the high—phos, high manganese ores). Similar to the Mesabi, with magnetite—banded oxide facies 3. Gogebic. and silicate facies predominant. Magnetite—banded rock grades locally into carbonate iron—formation, but much of the carbonate in the rocks can be shown to be the result of diagenesis. 4. Marquette. Lower part of the Negaunee iron—formation is carbonate fcies, which grades upward into silicate facies and that in turn to rock of the oxide facies that forms the uppermost part of the formation. The Vulcan iron—formation is almost entirely of the oxide 5. Menominee. facies; the lower member appears to be principally magnetite-banded rock; the upper member is principally hematite—banded rock. 6. Iron River—Crystall Falls district. The main iron—formation is carbonate facies, which is underlain by and gradational into a 50—foot black slate bed that contains 35—40 percent pyrite. The relationship between the iron—rich rocks and volcanism, stressed by many, is believed to be structural, not chemical: in the Lake Superior region both iron—deposition and volcanism are related to geosynclinal develop— rient during Huronian time. In Michigan, the lower Huronian rocks are iron— poor quartzite and dolomite-—typical "stable—shelf" deposits; most of the upper Huronian consists of iron—poor grayiacke and slate with associated volcanic rocks—a typical "geosynclinal" assemblage. Thus the iron—rich beds of the middle Huronian and lower part of the upper Huronian were deposited during a trasitional stage in structural history. The major environmental requirement for deposition of iron—formation is the closed or restricted basin; this requirement coincides in time with what would be a normal stage in evolu— tion of the geosyncline: namely, structural development of offshore buckles or swells that subsequently develop into island arcs characterized by volcanism. �UNIVERSITY OF 1INNESOTA Center for Continuation Study Minneapolis iL'. stitute April 1 — 2, on Lake Superior Geology FYRRHOTITE IRON FORMATIONS L. C. Kilburn and H. D. B. Wilson University of Manitoba, Winnipeg, Canada Large numbers of pyrrhotite iron formations are being discovered in the Canadian shield by airborne magnetic and electromagnetic surveys. One common type of pyrrhotite iron fonnation consists of banded pyrrhotite— magnetite mixtures in banded cherts and tuffs. other types of These deposits like many pyrrhotite deposit are barren of other base metal mineralization. Laboratory experiments show that H23 reacts with magnetite and converts it to pyrrhotite at temperatures as low as LOO° C. Iron silicates are con- verted in part to pyrrhotite at somewhat higher temperaturs. It is proposed that this type of banded pyrrhotite—magnetite deposit is a normal cherty iron formation which has been metamorphosed by heat and reaction with a sulphur—bearing gas, possibly H2S, to produce pyrrhotite from some of the magnetite and possibly from some of the iron—bearing silicates. �UNIVERSITY OF i1INNESOTA Center for Continuation Study Minneapolis iL April Thstitute on Lake Superior Geology 1 — 2, 19SS MAGNETITE, MAGHEMITE, HEMATITE Henry Lepp University of Minnesota, Duluth Branch, Duluth, Minnesota Differential thermal analyses of magnetite specimens show that magnetite goes through two stages of oxidation when heated in air. The first stage occurs at temperatures between 200 and to S60° C, and its intensity is related the fineness of the specimen. The second stage begins at approximately 6° C It and it is often not complete even at ioSo° C. is suggested that the first stage is a surface phenomena involving. the formation of maghemite (gamma Fe203) on the amount of maghemite specimen, and of a formed is a function of the speed of oxidation. magnetite nuclei. The the specific surface of the The second stage results from complete breakdown of the magnetite structure with oxidation to hematite (alpha Fe203). The behavior of synthetic siderite with respect to oxidation supports the foregoing explanation for the mechanism of magnetite oxidation. is commonly first oxidized to magnetite. Siderite Rapid oxidation of synthetic siderite at moderate temperatures produces gamma Fe203 as an end product, whereas slow oxidation of the same material results in the formation of alpha—Fe203. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis iL'. Institute on Lake Superior Geology April 1 — 2, 19SS KEWEENAWAN FELSITES OF THE BETE GRISE RAY AREA J. 14. Neilson and J. P. Dobl1 Michigan College of Mining and Technology, Houghton, Michigan Recent field and laboratory studies have been undertaken at the Michigan College of LiLining and Technology in an effort to determine the origin of certain felsite masses in the Bete Grise Bay area of the Keweenaw Peninsula. The felsite masses occur of interbedded lava flows and conglomerates. felsite and in the Keweenawan series Earlier workers mapped the occurrences and suggested intrusive relationships for some bodies extrusive relationships for others. Results of the present work in— dicate that thc felsites are rhyolitic differentiates of a magma which provided the chemically—related lavas of the region, and that some felsite masses bear intrusive relations to the older rocks while others were extruded as highly viscous flows. Criteria are presented for the field recognition of both types of felsitic occurrence. �UNIVERSITY OF MINNiSOTA Center for Continuation Study iviinneapolis 1)4 April 1 Institute on Lake Superior Geo1ogr — 2, 195 STRATIGRA.PHY IN THE CENTRAL PART OF THE CUYUNA DISTRICT, ItINNESOTA Robert G. Schmidt U. S. Geological Survey, Washington, D. C. (ie stratigraphy of the Cuyuna district has been shown to be much simpler than was previously believed. Almost all of the iron ore and mangan— iferous iron ore produced in the district is mined from one well—defined stratigraphic unit, here referred to as the "main" iron—formation. Other sediments may be roughly grouped as older or younger than the main iron— formation, and the stratigraphic positions of the other rocks are usually measured from it. The elastic sediments are dominated b3r argillites and siltstones. Part of the argillites older than the main iron—formation are sandy or silty, and there are lenses of quartzite near the contact with the iron—formation. Between 1,000 and about 2,000 feet stratigraphically below the iron—formation fine quartz siltstones are abundant. These siltstones are the oldest rocks that have been examined in this study. The main iron—formation is the best—knvwn stratigraphic unit in the district. Its lithologic variations are similar to some "typical" pre—Cambrian iron—formations in other districts. Extensive changes in lithology and thickness take place in short distances along the strike. Two general lithologic types have been recognized and mapped. The thin—bedded fades is a thinly laminated rock, which may contain any combination of chert, siderite, minnesotaite, stilpnomelane, and magnetite. The thick—bedded Lacies is composed of chert and red and brown iron oxides. In part of the district, the entire iron—formation is thick—bedded, in part it is all thin—bedded, and in about one third of the area the thick-bedded facies overlaps the thin-bedded facies and grades downward into it. Several lines of evidence suggest——but do not prove——that the thick—bedded facies was deposited in shallower water. In general, where the iron—formation is thin, the thick—bedded facies is present or dominates, granular textures may be present, and there are quartzite lenses in the adjacent older sediments. The younger sediments are generally finer elastics, partly ferruginous and partly carbonaceous. Tuffaceous argillites, tuffs, and lava flows make up the 300 feet immediately overlying the main iron—formation .J The volcanic rocks and some associated argillites, which are assumed to be reworked tuffs, are characterized by an unusually high Ti02 content, generally 1 to )4 percent and averaging about 2 percent. This itaniferous zone can be easily mapped even where the stratigraphic position of sediments cannot be determined by other means. It is therefore useful in the solution of stratigraphic problems. Part of the younger argillites is abnormally ferruginous and locally grades into lenses of lean "upper" iron—formation. The relation of these lenses to-a particular stratigraphic horizon is not known, but it is probable that they are not all of the same age. They have not been found closer to the main iron—formation than SOO feet. The transitional contacts of these lenses contrast with the sharp contacts of the main iron—formation . �UNIVERSITY OF IviIINESOTA Center for Continuation Study Minneapolis 114. Institute on Lake Superior April Geology STRTIA?HY 1 — 2, 19S5 OF MINNESOTA LAKE DEPOSITS F. M. Swain and N. Prokopovich University of Minnesota, Minneapolis, Minnesota Samples been studied • County; County; of the bottom sediments of several lakes in Minnesota have The lakes include Minnetonka, Hennepin Johanna, Ramsey County; Cedar, County; Prior, Scott Wright County; Burntside, St. Louis and Beaver Bay area, Lake Superior. A preliminary report of the results of these studies will be presented. �uNIvERsir OF MINNESOT Center for Continuation Study Minneapolis lLi. Institute on Lake Superior Geology April 1 — 2, 195S A GRAVITY STUDY OF THE LJKE SUPERIOR SYNCLINE Edward Thiel University of Wisconsin, Madison, Wisconsin Six years ago the Geophysics Section at Wisconsin began a program of regional gravitational mapping in the western United States and .1aska. The first traverses leading westward from Madison across the northern mid—contiIn some cases nent in 19)49 detected regions of abnormally high gravity. this "high" was flanked on both sides by gravity "lows" • As the data accumulated it became evident that the anomalous area formed a more or less linear feature, offset in several places, extending from the Lake Superior region southward into Kansas. On the south, the anomalous area was blanketed by Paleozoic sediments, and the scarcity of deep boreholes made interpretation difficult. Therefore, the cause of the anomaly was sought first at its northern end, about Lake Superior, where the pre—Canibrian rocks outcrop, facilitating a correlation of gravity and geology. In the Lake Superior area the large regional anomaly is associated with rocks of Keweenawan age. Positive Bouguer anomalies occur over the dense lava flows of the Keweenaw Peninsula, northwestern Wisconsin, northeastern Minnesota, and Isle Royal; these anomalies reach +60 mgals in Wisconsin and Minnesota. The gravity "lows" occur over basins filled with low density sediments of Upper Keweenawan age; the most striking example is the —90 mgal low on the Bayfield Peninsula. second thick accumulation of sedimentary rocks is suggested. to underlie the —90 mgal low at Cinber1and. The structre exhibited by the. Pale ozoic rocks (River Falls Syncline) in the Curaberland region may represent only the last stage in the development of the more fundamental Keweenawan structure at depth Steep gravity gradients indicate the Douglas Fault. A second major symmetric to the Douglas Fault is mapped in northwestern Wisconsin on the opposite side of the Lake Superior Syncline. The center of the syncline has been thrust upward between the two faults as a horst. The interruption fault of the positive anomaly near eUon is related to the intrusion of a granitic mass. Further detailed geologic correlation is presented in six structure sections along lines of gravity traverse. An isostatic correction cannot significantly reduce the gravity differentials in the Lake Superior region. Complete local isostasy cannot exist here, but regional isostasy which considers the "highs" and "lows" together may prevail. A "geological correction" which takes account of geology to a radius of 20 miles from a station and to a depth of 38,000 feet was computed for gravity stations in Wisconsin. Such a correction accounts for the greater part of the anomalies. Any attempt to compute variations in the thickness of crustal layers without first allowing for the near—surface geology would have led to serious error in this region. �UNIVERSITY OF IVaNNESOTA Center for Continuation Study Minneapolis it1. Institute on Lake Superior April Geology 1 — 2, l9S MEGASCOPIC PETROFABRICS USED IN DECIPHERING STRUCTURE James W. Trow U. S. Geological Survey, Michigan State College, East Lansing, Michigan Megascopic rock fabrics are integrated with lithology, gross structure, and microscopic petrofabrics in an outline of the sequence of orogenic events of late Huronian time in a part of Dickinson County, Michigan. The fabrics of these Huronian and pre—Huronian rocks are compared to the fabrics of a somewhat similar lithologic sequence of' Cambro—Ordovician and pre- Cambrian rocks of Dutchess County, New York, described in detail in the literature by Robert Balk, and briefly examined by the author of the present paper. Statistical equal—area diagrams of rock fabrics support the conclusions that the rocks of the Dickinson County area experienced i) late-Huronian deformation within the pattern determined largely by the anisotropism of the pre—Huronian rocks, 2) and strong following dip—slip underthrusting and ramping, 3) deformation in same instances facilitated by the ding and the strike—slip movement contemporaneous to development of slip cleavage parallel to bed- gneissic foliation, and L1.) metamorphism of waning stages of the orogeny. basic intrusives during �flTI1jSITy OF IvtENNESOTA Center titute k for Continuation Study Minneapolis 14 April 1 — 2, 1955 prior Geology ON THE ORIGIN OF THE LAKE SUPERIOR IRON ORES Stanley University A. Tyler of Wisconsin, Madison, Wisconsin The origin of the Lake Superior iron ores has intrigued geologists for the past one hundred years. Concepts pertaining to ore genesis advanced by Foster and Whitney, Whittlesey, Lapham, Brooks, Irving and Van Hise, Van Hise and Leith, Gruner and Tyler are briefly summarized as a basis for discussion Although many diverse opinions have been expressed regarding the origin ores there seems to be more or less general agreement among the more of the recent 1. workers upon the following points: The iron formations of the Lake Superior region were originally comquantities of iron posed dominantly of silica, with important but subordinate carbonate, iron silicate, iron oxide and iron suiphide. 2. The iron ore is largely a residual product formed by alkaline oxygen— bearing solutions which oxidized the ferrous minerals to the ferric state and removed the silica in solution. . Migration of iron and replacement has played an important part in the development of some — perhaps many — ore bodies. 4. Fractures, faults, joints, breccia zones, bedding planes, dikes, sills and impervious sedimentary horizons have exerted a marked control upon the path that the ore forming solutions took through the iron formation. 5. The period of ore formation was largely if not entirely restricted to the pre—Gsxnbrian. In contrast, general lack of agreement, diverse opinions and some controversy has centered around the following points: 1. Whether the solutions that oxidized the iron and leached the silica were rising hydrothermal waters or cold descending meteoric waters. 2. Whether the silica that was leached from the iron formation during the process of ore formation was largely in the form of chert (quartz)..:or largely in the form of iron silicates such as ninnesotaite, stilpnomelane, chlorite and grunerite. Thiphasis placed upon hot waters, alkaline waters or a silicate facies of the iron formation as necessary requisites for ore formation calls for the most optimum conditions for ore formation. Since the time factor is unknown it seems more probable that the ores may have developed rather slowly under less optimum conditions. Mineralogical and chemical evidence is cited to substantiate the concept that both acid and alkaline solutions have passed through some of the iron ore bodies of the Lake Superior region. is The iron formation is considered to be a peculiar sedimentary sensitive to the presence of oxygen and to the loss of silica. cept leads to the conclusion that the ores may have formed under differing sets of environmental conditions. rock which This con- at different times �UNIVERSITY OF MINNESOTA Continuation Study Minneapolis 14 Center for Institute on Lake Superior Geo1 April 1 2, 1955 THE WORK OF TEE RIBBING LABORATORY OF THE DIVISION OF LAND AND MINERAlS M. P. Walle Division of Land and Minerals, Department of Conservation, Ribbing, Minnesota Following is a list of the more Important activities: 1. Geophysical work In connection with state-owned properties, or along public roads to check possibilities for ore or rock materials, largely magnetic and resistivity surveys. Of special Importance are areas south of the Iron formation Involving Cretaceous ore possIIiitiee, for example In the region between Buhi end Kinney. Resistivity tests are uscful west of ovey where the xnagietIc survey does not help, because of the nonmagnetic character of the iron formation. 2. Exploration work on state permits and leases. This Includes visual classification for separating the formatIon into Its four main divisions and for sorting of ore materials Into mercharitable ore, wash ore, jig ore, and magnetic and non-magnetic taconite. Stratigraphic work in the mines is also carried out. 3. An important service is supplying Ir.formaion on drill records and access to drill cores of work done on state lands. The sample library at Hibbing supplements the U. S. Bureau of Mines core library at Fort Snelling. 4. Development of a circuit on the Dinge-Davis magnetic separator permitting separation of samples Into high-grade concentrates, magnetic middlings, arid non-magnetic tailings. This separation facilitates microscopic and spectrographic examinations. 5. Ground mapping of certain areas of state-owned land where anomalies are shown by aerial magnetic surveys. 6. Study of the Duluth gabbro contact areas of Interest for copper, nickel, and other metals. 7. Cooperation with various organizations in the preparation of symposiums on mining and geology. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis Institute iL April 1 — on Lake Superior Geology 2, 19% ORIGIN OF THE BIWABIK IRON—FORI&ATION, MESABI RANGE, MINNESOTA D. A. White Carter Oil Company, Tulsa, Oklahoma The later Precambrian Animikie group in northeastern Minnesota consists of three sedimentary units: the Pokegama (quartzite), Biwabik (iron—rich rock), and Virginia (argillite) formations. "Mesabi range" designates the preglacial outcrop belt, to 3 miles wide and 120 miles long, of the Biwabik formation. Varieties of iron—rich rock ("taconite") are either granular or slaty and consist dominantly of chert, iron silicates, magnetite, and siderite. The Lower Cherty, Lower Slaty, Upper Cherty, and Upper Slaty members of the Biwabik formation, which averages 600 feet in thickness, can be further subdivided into smaller lithic units. These members are relatively uniform along most of the range, but only one cherty and one slaty member exist on the Westernmost Mesabi, where the lithic units are intertongued. The Pokegama, Biwabik, and Virginia formations are considered conformable. Chert, greenalite, ininnesotaite, stilpnomelane, and siderite probably formed rocks are essentially unmetamorphosed. magnetite, some hematite, The either during or shortly after deposition. The Poke galna and Biwabik formations were probably produced by the migration of a series of coexisting environments of deposition during an advance, a retreat, and a second advance of the Animikie sea. The deposits formed, during the retreat, in successive environments seaward from shore, were clastic material, carbonaceous—pyritic mud, chert—siderite, chert— magnetite, and iron silicate. Fine clastics of the Virginia formation, perhaps furnished by an outburst of volcanic activity, spread across the former environments of chemical sedimentation. Possible conditions of iron sedimentation were as follows: derivation of iron and silica by weathering of a low—lying land mass, perhaps under an atmosphere rich in carbon dioxide, and a seasonal climate; tectonic stability; and deposition in a shallow, quiescent epicontinental sea. �UNIVERSITY OF NNESCJIA Center for Continuation Study Minneapolis 14 April 1 Institute on Lake Superior Geolojr 2, 1955 SIJNMRY OF THE SUB—DIVISIONAL CORRELATION OF THE MLDDLE HtJRONIAN IRON—FORMATIONS OF THE LAKE SUPERIOR DISTRICT J. F. Wolff, Sr. Duluth, Minnesota For a generation or more there has been general agreement among of the Lake Superior District, that, based on general geologic associations, the major iron—ore producing formations of the (older) Middle Huronian series of iron bearing rocks were of the same general age and broadly of similar character. geologists A great many geologists have known, especially of later years, that fairly comparable subdivisions of this Middle Huroniari iron—formation can be found in the different districts. The presenter of this brief contribution is not aware of the publication of any correlation diagram which shows major subdivision of the older iron—formation of Mesabi, Cuyuna, Gogebic, Marquette and old Menominee districts into four main layers and even the division of some of these into minor layers having similar characteristics. This contribution presents such a correlation diagram in color, projected on a screen for convenience of the audience. Four major divisions of the iron—formation are shown,—from the top down being — Upper Slaty, Upper Cherty, Lower Slaty and Lower Cherty, lying between a basal quarteite and quartz—slate and an overlying very thick black—slate and graywacke in places, which locally has a conglomerate and quartzite—quartz—slate at its base, A very great erosion period intervened between the top of the Upper Slaty and the beginning of deposition of the Upper Huronian conglomerate— quartzite—slate series of rocks so that in places only remnants of the Upper Slaty Division are left. In the main area of the Marquette District there is no remnant of it so far as the writer knows but north of Crystal Falls at the Arnasa—Porter mine, was found at the top of the Negaunee iron—formation. A few of the minor subdivisions are shown on the diagram. it The major unconformity between Upper and Middle Huronlan rocks is shown graphically, and the relative position of the Upper Huronian iron— formations of the Iron River, Crystal Falls, Florence, Menominee, Marquette— Gwinn, Gogebic and cuyuna districts is shown also on the diagram, which was compiled from aU available sources, including the author's work or visits in all the districts and interviews at different times with geologists active in the several areas. Minor details may be controversial especially with respect to the greenstones in the Iron River, Crystal Falls and Florence districts whose position in the geologic column may still be open to question and further exploration evidence. �UNIVERSITY OF MINNESOTA Center for Continuation Study Minneapolis l Institute April 1 — on Lake Superior Geology 2, l9S EXPLORATION FOR NICKEL AND COPPER IN NORTHERN MINNESOTA GEOCHB1'1ICAL Donald H University of Minnesota, Yardley Minneapolis, Minnesota Geochemical tests for nickel and copper in glacial soil from the Ely district show that pronounced anomalies overlie mineralized Duluth gabbro The geochemical pattern demonstrates that the mineralization is parallel to the gabbro—granite contact, but 300 feet or so from the contact. The profiles of copper distribution are similar to the nickel profiles, with copper present in greater amount. Both metals are confined to the finer soil fractions. The processes by which the heavy elements migrate is not clear. It is believed that natural earth currents may play some part in distribution of the heavy elements. The vertical distribution is being tested to facili- tate investigation of the process of migration. �UNIVERSITY OF MINNESOTA for Continuation Study Minneapolis iL Center Institute on Lake Superior Geolor April 1 — 2, 19SS STUDIES OF STRATIFIED ROCKS OCCURRING BELOW THE HtJRONIAN SUCCESSION IN THE MARQUETTE DISTRICT, MICHIGAN Justin Zinn, Gerald L Brooke, Theodore Engel, and Richard Hagni Michigan State College, East Lansing, Michigan Several remnants of metamorphosed stratified rocks are known to occur along the margin of the Marquette syncline or adjacent to nearb;,r Huronian synclines in the Marquette district. greater These remnants are age than the Mesnard quartzite apparently all of Three such remnants have been restudied so far and they are the Lake 'nchantment (Mud Lake) sediments, the Holyoke formation and the Kitchi schist. The restudies included detailed mapping and petrographic examination of the rocks of each area in the attempt to eatablish more definitely the age and origin. The Holyoke formation and the Lake Enchantment sediments overlie the Keewatin greenstones with marked tion unconformable contacts and the Kitchi forma- is believed to have a similar relationship. belong These formations therefore to the time interval between the Keewatin and in Michigan. Each of these sedimentary the base of the Huronian remnants is distinctly different from the others and they are not believed to be of the same age. The Holyoke formation appears to be tillite and it may provide a clue in correlating the Michigan Huronian with that on the north shore of Lake Huron. �UNIVERSITY Oi MINNESOTA Center for Continuation Study Minneapolis iL'. Institute April on Lake Superior Geology 1 — 2, 1955 BOTTOM CORING IN LAKE SUPERIOR James H. Zuinberge University During sediments the of Michigan, Ann sruner of 1953 of Lake Superior. several Arbor, Michigan cores were recovered from the bottom The research was accomplished through a coopera- tive venture between the U. S. Fish and Wildlife Service and The Great Lakes Research Institute, a research organization of the University of Michigan dedicated to scientific investigations of the Great Lakes. The cores were obtained with a gravity coring rig which consisted of a weighted 5—foot length of 3—inch diameter pipe to which two 10—foot sections of 2—inch I. D. diameter pipe was attached • The maximum core recovery was about 8 feet. Ten cores were taken at Stations between Keweenaw Bay and Isle Royale, and Grand Marais, Minnesota and Bayfield, Wisconsin. fine grained ranging from clay to silt size. cores is their color variation. The core material is The chief difference in the Sortie are reddish, ranging from 10 R 3/2 to 2.5 YR 5/2 (Munsell), while others are grey. is red and the lower 1 foot is grey. In one core the upper 6 feet No relationship between color and depth of water or color and geographic location is apparent. A mineralogical study of one core recovered in 630' of water showed that the composition is about 75 clay minerals. percent quartz and feldspar and only 25 percent The latter group include kaolinite and a possible interlayered chiorite—illite mineral as indicated by X—ray diffraction studies presently under way at Ohio State University. � 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 Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre 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 Institute on Lake Superior Geology: Proceedings, 1955 Description An account of the resource Proceedings of the Institute on Lake Superior Geology, University of Minnesota, April 1-2 1955. 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 1955 Format The file format, physical medium, or dimensions of the resource PDF Language A language of the resource English