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Classic Precambrian geology of northeast Minnesota

By
Mark A. Jirsa
Mark A. Jirsa
Minnesota Geological Survey, 2642 University Avenue, St. Paul, Minnesota 55114-1032, USA
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;
John C. Green
John C. Green
Department of Geological Sciences, University of Minnesota–Duluth, Heller Hall 229, 1114 Kirby Drive, Duluth, Minnesota 55812–3036, USA
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Published:
January 01, 2011

ABSTRACT

This field trip is an overview of Precambrian terranes in northeastern Minnesota using some of the most illustrative and accessible exposures—the term "classic" refers to the fact that many were the basis for earliest geologic study of the Precambrian and continue to be exemplary. The geology is presented in the context of major orogenic, rifting, and meteorite impact events during evolution of the North American continent. The Archean rocks are the products of three periods of orogenesis: the ca. 2695 Ma Shebandowanian orogeny that created major folds and thrust stacks; the ca. 2680 Ma Minnesotan orogeny that produced regional transpressive fabrics, folds, and metamorphism to greenschist-amphibolite grade; and a third event that produced localized faulting and folding of earlier structures and fabrics. The Sheban-dowanian may represent collision of the Wawa subprovince with the composite Superior superterrane to the north. The Minnesotan can be attributed to oblique collision of the Minnesota River Valley subprovince with the Superior superterrane. Structures bounding major components of the Superior Province are locally inferred to be thrust faults that formed during terrane assembly. Their vergence and offset histories are derived from seismic surveys in Minnesota and extrapolation from Lithoprobe and NATMAP transects in adjacent Canada. The Paleoproterozoic rocks are the products of three orogenic and rifting events, reflecting continued continental growth at Geons 18, 17, and 16. Mesoproterozoic rocks result from Geon 11 continental rifting, producing volcanic and sedimentary rocks of the Keweenawan Supergroup and plutonic rocks of the Midcontinent Rift Intrusive Supersuite.

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GSA Field Guide

Archean to Anthropocene: Field Guides to the Geology of the Mid-Continent of North America

James D. Miller
James D. Miller
Department of Geological Sciences and Precambrian Research Center University of Minnesota-Duluth Duluth, Minnesota 55812 USA
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;
George J. Hudak
George J. Hudak
Precambrian Research Center Natural Resources Research Institute 5013 Miller Trunk Highway Duluth, Minnesota 55811 USA
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;
Chad Wittkop
Chad Wittkop
Department of Chemistry and Geology Minnesota State University Mankato, Minnesota 56001 USA
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;
Patrick I. McLaughlin
Patrick I. McLaughlin
Wisconsin Geological and Natural History Survey Madison, Wisconsin 53705 USA
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Geological Society of America
Volume
24
ISBN electronic:
9780813756240
Publication date:
January 01, 2011

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