MINNESOTA GEOLOGICAL SURVEY INFORMATION CIRCULAR 34 PRECAMBRIAN GEOLOGY OF THE SOUTHERN CANADIAN SHIELD AND THE EASTERN BALTIC SHIELD U.S.A.-U.S.S.R.-Canada Joint Seminar, August 21-23, 1990, Duluth, Minnesota UNIVERSITY OF MINNESOTA Minnesota Geological Survey Priscilla C. Grew, Director INFORMATION CIRCULAR 34 PRECAMBRIAN GEOLOGY OF THE SOUTHERN CANADIAN SHIELD AND THE EASTERN BALTIC SHIELD U.S.A.-U.S.S.R.-Canada Joint Seminar, August 21-23, 1990, Duluth, Minnesota Edited by Richard W. Ojakangas University of Minnesota, Duluth Convened with the support of United States National Science Foundation (N SF-INT -9000365) Geological Survey of Canada University of Minnesota, Duluth, Department of Geology Minnesota Geological Survey Ontario Geological Survey Union of Soviet Socialist Republics Academy of Sciences Soros Foundation-Soviet Union University of Minnesota St. Paul, 1991 ISSN 0544-3105 The University of Minnesota is committed to the policy that all persons shall have equal access to its programs, facilities, and employment without regard to race, religion, color, sex, national origin, handicap, age, veteran status, or sexual orientation. iii EDITOR'S FOREWORD The geologic histories of the Canadian and Baltic Shields in North America and Europe, respectively, are broadly similar, and the topic was discussed during a conference and field trip involving North American and Russian participants in the late summer of 1990. During a two-day meeting prior to the field trip, twelve North American and eleven Soviet geologists presented papers, and participants discussed a variety of problems and ideas in Precambrian stratigraphy, sedimentology, tectonics, magmatism, industrial minerals, and metallogeny. Special emphasis was placed on problems of correlation. All papers were simultaneously interpreted by Senior Translator and Interpreter Grigori Sokolov of the Institute of Geology, Karelian Branch, U.s.s.R. Academy of Sciences, who accompanied the Russian delegation. His ability contributed greatly to the meeting's success. In addition to the speakers, thirty-eight geologists attended the conference: four Canadians, two Finns, and thirty-two Americans, including eight graduate students. As a result of the seminar and field trip, exciting and promising opportunities for continued cooperation were identified. Specific proposed activities include meetings, field excursions, short courses, joint publications, individual research-oriented exchanges, and joint projects. Involvement of young geologists was especially encouraged to promote long-term cooperative relationships. Opportunities also were identified for cooperation with other international projects, such as existing bilateral programs and the International Geological Correlation Program. It was mutually agreed that in 1991-1992, the Institute of Geology, Karelian Research Center, and the Kola Research Center of the USSR Academy of Sciences will host conferences and field trips on Proterozoic and Archean geology and metallogeny in the eastern Baltic shield. In 1991, the field program will emphasize Proterozoic geology, and in 1992, Archean geology. Other joint activities in the future will depend on the outcome of the 1991 and 1992 meetings. It was the intent of the organizers to bring this joint activity to the attention of officials involved in relevant international programs. Toward that end this proceedings volume has been published by the Minnesota Geological Survey. The body of this report consists of two parts; the first is a series of short papers that provide an overview of the Precambrian geology in the Great Lakes Region; the second part consists of a similar overview of the eastern part of the Baltic Shield. North American participants were asked to submit extended abstracts that could be collated and distributed at the time of the meeting. Those contributions appear in this volume for the most part as they were received from the authors. It also was planned to distribute the contributions of the Russian participants at the time of the meeting, but several subsequent events delayed distribution until after the meeting. These papers were somewhat revised and edited after the meeting, and the revised versions are included herein. Avis Hedin and Joan Hendershot assisted in the laborious process of retyping successive revisions. Mary Nash, Executive Secretary of the Department of Geology at Dulcth, provided outstanding administrative support. All of the conveners, Priscilla Grew and G.B. Morey of the Minnesota Geological Survey, K.D. Card of the Geological Survey of Canada, and RW. Ojakangas of the University of Minnesota-Duluth, wish to thank the following organizations for their support of the 1990 meeting: U.s. National Science Foundation, U.S.5.R Academy of Sciences, Geological Survey of Canada, University of Minnesota­ Duluth Department of Geology, Minnesota Geological Survey, Ontario Geological Survey, and the Soros Foundation - Soviet Union. RW. Ojakangas, Editor Professor of Geology University of Minnesota - Duluth Duluth, Minnesota iv GENERAL COMPARISON OF THE CANADIAN AND BALTIC SHIELDS K.D. Card, Geological Survey of Canada, Ottawa Superior Kola Age span 3.1-2.6 Ga 3.1-2.6 Ga Major orogenies ca. 2.9 Ga - "Wanipigowan" 3.1-2.9 Ga - Saamian ca. 2.7 Ga - Kenoran 2.9-2.7 Ga - Lopian (Rebolian) Major 1) 3.1-2.8 Ga tonalitic-granodioritic 1) 3.1-2.9 Ga tonalitic-granodioritic lithotectonic units plutonic rocks with greenstone remnants plutonic rocks with greenstone remnants forming early sialic crustal elements forming early sialic crustal elements 2) 3.0-2.8 Ga platformal sequences (quartz 2) 2.9-2.7 Ga Kola Peninsula gneisses? arenite, stromatolitic marble, mafic ultramafic vols) unconformable on older plutonics 3) 2.8-2.7 Ga greenstone belt sequences; 3) 2.9-2.6 greenstone belt sequences; submarine plain mafic/ultramafic komatiitic, tholeiitic, and calc alkalic tholeiitic-komatiitic sequences; central volcanics and syn-volcanic plutons volcanic complex, tholeiitic-calcalkalic sequences and synvolcanic plutons, Timiskaming-type alluvial sediment­ shoshonitic/ alkalic volcanic sequences 4) ca 2.7 Ga low- to high-grade 4) 2.9-2.6 Ga high-grade metasedimentary metasedimentary sequences sequences 5) 2.7-2.6 Ga plutonic suites; mafic-felsic 5) 2.7-2.6 Ga plutonic suites; syn- to post­ (gabbro to granite), syn- to post-tectonic tectonic re Lopian orogeny (Chupa cycle) re Kenoran orogeny 6) Granulite gneisses uplifted in the late 6) Granulite gneisses uplifted in the Early Archean or Early Proterozoic Proterozoic Major terranes 1) Older (3.1-2.8 Ga) crustal elements of 1) Older Saamian (3.1-2.9 Ga) crustal and their Sachigo, Uchi, and Wabigoon subprovinces; elements of Karelian province, tonalite­ characteristics tonalitic granodiorite gneiss with greenstone granodiorite gneiss with greenstone remnants and local platformal cover remnants sequences 2) Younger (2.8-2.7 Ga) granite-greenstone 2) Younger (2.9-2.7 Ga) granite-greenstone subprovinces, e.g. Abitibi, low-to medium­ terranes, i.e. Karelian belts, low- to grade, low P metamorphism, polyphase medium-grade, low P metamorphism, deformation polyphase deformation v 3) Metasedimentary gneiss belts, e.g. 3) Linear belts of amphibolite-granulite Quetico, low- to high-grade metamorphism, facies metasedimentary gneiss, e.g. abundant granitic intrusions, polyphase Belomorian, early recumbent folding; deformation including early thrusts, multiple medium to high pressure meta recumbent folds accompanying plutonism 4) Granulite terranes uplifted during Early 4) Granulite terrane uplifted during Early Proterozoic collisional events, e.g. Proterozoic collisional event; i.e. Lapland Kapuskasing structural zone granulite belt Late Archean­ Craton formation and stabilization during Craton formation and stabilization during Early 2.7-Ga Kenoran orogeny followed by rifting 2.7-Ga Lopian orogeny followed by rifting Proterozoic and deposition of Huronian volcanic and and deposition of Lapponian volcanic and history sedimentary sequences ca. 2.5-2.4 Ga ago sedimentary sequences ca 2.6-2.3 Ga ago Tectonic Subduction-driven, southward-younging Subduction-driven, westward -younging in terpre ta tion accretion of volcanic arc, back-arc, and accretion of volcanic arc, back-arc, and sedimentary prisms accompanied and sedimentary prisms accompanied and followed by plutonism and transpression followed by plutonism (Gaal and (Card, 1990) Gorbatschev, 1987) vii TABLE OF CONTENTS.AND SCHEDULE Page Editor's foreword iii General comparison of the Canadian and Baltic Shields iv Tuesday, 8/21/90 1930 Icebreaker Party, UMD Campus Club VVednesday, 8/22/90 0700 Breakfast, UMD Dining Center Seminar, Life Science Building, Room #185 0845 "VVelcomes" Chancellor Lawrence Ianni, UMD Priscilla Grew, Director, Minnesota Ken Card, Geological Survey of Canada VS. Kulikov, Deputy President, Karelian Branch, USSR Academy of Sciences Richard Ojakangas, University of Minnesota-Duluth Chairs: M. Kehlenbeck and Michael Mudrey, Jr. 0900 P. K Sims Precambrian geology of the Lake Superior 1 region--An overview 0930 P.C Thurston Superior Province greenstone belts 9 1000 Richard H. Sutcliffe Archean plutonic rocks in the southern 16 Superior Province: Magmatism during arc construction and arc accretion 1030 Coffee Break 1100 Peter J. Hudleston Structures in Archean rocks of the southern 23 Superior Province 1130 Klaus J. Schulz Tectonic evolution of the Early Proterozoic 29 Penokean orogen 1200 IS. Klasner & Bi-polar tectonic transport in the Penokean 33 G.L LaBerge orogen