. ~ ._S GEQLOGISCHE DJENSIJ' $:1 0 lOG J S C H 8 UR E A.tiI VOORHST " Jl' , . i ~ .' . MIJN(;ESIED ~ill~.1 -. i[ Ii '11 '. GEOLOGY OF MINNESOTA: A Centennial. Volume. P. K. Sims and G. B. Morey, editors Rijks Geologische Dienst Heer/en Bibliotheek 2252 GEOLOGY OF MINNESOTA: A CENTENNIAL VOLUME GEOLOGY OF MINNESOTA: A CENTENNIAL VOLUME In honor of George M. Schwartz P. K. Sims and G. B. Morey, editors Published by the Minnesota Geological Survey on the occasion of its 100th Anniversary 1972 Minnesota Geological Survey University of Minnesota 1633 Eustis St. St. Paul, Minnesota 55108 Printed in the United States of America TABLE OF CONTENTS Page. Preface ........................................................................................ Xl List of Authors ................................................................................. xii Contributors .................................................................................... xiii An Appreciation ................................................................................. xv CHAPTER I - RESUME OF GEOLOGY OF MINNESOTA - P. K. Sims and G. B. Morey ......... 3 Precambrian Era ..... , , .......... , .......................................................... 3 Paleozoic Era . ........... , .............................. , ................................... 13 Mesozoic Era 14 Cenozoic Era 15 CHAPTER II - HISTOR Y OF INVESTIGATIONS HISTORY OF GEOLOGIC INVESTIGATIONS - P.K. Sims ............................... 21 Pioneer Period .................. ......................................................... 21 The Period 1872-1900 . .. .......................................................... 21 The Period 1900-1911 ........................... ....................................... 22 The Period 1911-1961 .................................................................... 23 The Period Since 1961 ....................................................................... 26 GEOCHRONOLOGY IN MINNESOTA - S. S. Goldich ........................................ 27 Decay Constants ....... ............................................................... 27 Minnesota River Valley .................................................................... 27 Northern and East-Central Minnesota .......................................................... 32 Summary and Concluding Remarks ............................................................. 36 Acknowledgments .......................................................................... 37 CHAPTER III - EARLY PRECAMBRIAN NORTHERN MINNESOTA, GENERAL GEOLOGIC FEATURES - P. K. Sims ................... 41 Stratigraphic Framework .................................................................... 41 Coutchiching Problem ................................................................. 41 Granitic Rocks .................... ................................................. 42 Volcanic-Sedimentary Sequences .............................................................. 44 Tectonic Framework ....................................................................... 45 Post-Algoman ivletamorphism ................................................................ 46 VERMILION DISTRICT AND ADJACENT AREAS - P. K. Sims . .............................. 49 History of Investigations .................................................................... 49 General Geology ........................................................................... 50 Summary of Geologic History ......................................................... 62 METAVOLCANIC AND ASSOCIATED SYNVOLCANIC ROCKS IN VERMILION DISTRICT - P. K. Sims ..................................................................... 63 Metavolcanic Successions .................................................................... 63 Extrusive Mafic Lavas ... 67 Intrusive Metadiabase ....................................................................... 67 Extrusive Felsic Lavas ...................................................................... 68 Intrusive Porphyries ........................................................................ 68 Pyroclastic Rocks .......................................................................... 70 Epiclastic Rocks ........................................................................... 71 Chemical Compositions ..................................................................... 71 UL TRAMAFIC ROCKS IN VERMILION DISTRICT - 1. C. Green ............................. 76 Hornblende Peridotite in Ely Greenstone ....................................................... 76 Differentiated Mafic-Ultramafic Bodies in Newton Lake Formation ................................. 76 Similarities to Ultramafic Rocks in Northwestern Ontario ........................................... 77 BANDED IRON-FORMATIONS IN VERMILION DISTRICT - P. K. Sims . ..................... 79 Soudan [ron-formation ...................................................................... 79 Iron-formation in Ely Trough ................................................................ 81 v Page Other Iron-formations ....................................................................... 81 Origin ................................................................................... 81 GRA YW ACKES AND RELATED ROCKS OF KNIFE LAKE GROUP AND LAKE VERMILION FORMATION, VERMILION DISTRICT - Richard W. Ojakangas .................. 82 Knife Lake Group ......................................................................... 83 Lake Vermilion Formation .................................................................. 86 Conclusions ................................................................................ 88 GRANITE-BEARING CONGLOMERATES IN THE KNIFE LAKE GROUP, VERMILION DISTRICT - Roger K. McLimans ............................................... 91 Description of Conglomerate Units ............................................................ 91 Conglomerate Matrices and Associated Graywackes ............................................... 93 Provenance ................................................................................ 93 Sedimentation .............................................................................. 93 Conclusions ................................................................................ 97 BURNTSIDE GRANITE GNEISS, VERMILION DISTRICT - P. K. Sims and M. G. Mudrey, Jr . .. 98 SAGANAGA BATHOLITH - Gilbert N. Hanson . .............................................. 102 Geologic Setting ............................................................................ 102 Saganaga Tonalite .......................................................................... 104 Structure .................................................................................. 105 Geochemistry and Petrogenesis ................................................................ 105 VERMILION GRANITE-MIGMATITE MASSIF - D. L. Southwick ........... .................. 108 Rock Nomenclature ......................................................................... 108 Regional Setting ............................................................................ 109 The M igmatitic Rocks ...................................................................... 110 Massive Granitic Rocks Older than the Major Pink Granite ....................................... III Massive Pink Granite and the Neosome of Granite-Rich Migmatite ................................. 114 Summary of Igneous Events .................................................................. 116 Chemical Composition ...................................................................... 116 Internal Structure .......................................................................... 117 Conclusions and Speculations ................................................................ 118 GIANTS RANGE BATHOLITH - P. K. Sims and S. Viswanathan ............................... 120 History of Investigations ..................................................................... 121 Rock Nomenclature ....................................................................... 121 Western Part .............................................................................. 121 Eastern Part ................................................................................ 130 SYENITIC PLUTONS AND ASSOCIATED LAMPROPHYRES - P. K. Sims and M. G. Mudrey, Jr .. 140 Snowbank and Kekekabic Stocks .............................................................. 140 Lamprophyre Bodies in Eastern Part of Vermilion District ......................................... 144 Syenitic Rocks and Related Lamprophyres in Western Part of Vermilion District ...................... 145 Genetic Inferences ......................................................................... 152 PETROLOGY OF THE LAMPROPHYRE PLUTON NEAR DEAD RIVER - Arthur L. Geldon ... 153 Description of Pluton ....................................................................... 153 Petrography ............................................................................... 153 Petrochemistry ............................................................................. 155 Conclusions ............................................................................... 158 LINDEN PLUTON - P. K. Sims, David Sinclair, and M. G. Mudrey, Jr . ........................... 160 RAINY LAKE AREA - Richard W. Ojakangas ................................................ 163 Rock Units ...............................................................................