Archean Geology of the Northern Block of the Ishpeming Greenstone Belt, Marquette County, Michigan

Archean Geology of the Northern Block of the Ishpeming Greenstone Belt, Marquette County, Michigan
Title Archean Geology of the Northern Block of the Ishpeming Greenstone Belt, Marquette County, Michigan PDF eBook
Author Rodney C. Johnson
Publisher
Pages 28
Release 1991
Genre Geology
ISBN

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U.S. Geological Survey Bulletin

U.S. Geological Survey Bulletin
Title U.S. Geological Survey Bulletin PDF eBook
Author
Publisher
Pages 372
Release 1983
Genre Geology
ISBN

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U.S. Geological Survey Bulletin

U.S. Geological Survey Bulletin
Title U.S. Geological Survey Bulletin PDF eBook
Author Gene L. LaBerge
Publisher
Pages 346
Release 1991
Genre Faults (Geology)
ISBN

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A reconnaissance study carried out in conjunction with regional geologic mapping.

New Publications of the Geological Survey

New Publications of the Geological Survey
Title New Publications of the Geological Survey PDF eBook
Author Geological Survey (U.S.)
Publisher
Pages 746
Release 1991
Genre Geology
ISBN

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New Publications of the U.S. Geological Survey

New Publications of the U.S. Geological Survey
Title New Publications of the U.S. Geological Survey PDF eBook
Author
Publisher
Pages 64
Release 1991
Genre Geology
ISBN

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Geology of Volcanic Rocks in the South Half of the Ishpeming Greenstone Belt, Michigan

Geology of Volcanic Rocks in the South Half of the Ishpeming Greenstone Belt, Michigan
Title Geology of Volcanic Rocks in the South Half of the Ishpeming Greenstone Belt, Michigan PDF eBook
Author Theodore J. Bornhorst
Publisher
Pages 24
Release 1993
Genre Geology
ISBN

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The south half of the Ishpeming greenstone belt is domi- nated by a thick succession of subaqueously erupted volcanic rocks. A regional structural interpretation of the belt provides a framework for placing this succession in a stratigraphic order. The south half of the Ishpeming greenstone belt preserves the remnants of overlapping subaqueous volcanic complexes within an arc system. The Kitchi Formation, as redefined herein, comprises the lower half of the volcanic succession and is subdivided into three informal units. The basal basalt flow unit is composed of pillowed, tholeiitic, basalt flows and minor banded iron-formation and dacitic tuff. It is overlain by the second and third units, which are tuff and lahar (volcanic debris flow) units that inter- finger with one another. These units range in composition from calc-alkalic basalt to dacite. The Kitchi Formation represents an evolving tholeiitic, mafic shield to calc-alkalic, mafic to felsic subaqueous volcano. The Mona Formation, which is redefined herein, is in structural contact with the Kitchi Formation, but is likely younger. It is subdivided into three informal units. The base consists of a basalt flow unit, which is composed of pillowed, tholeiitic to magnesium-rich basalt flows and minor amounts of banded iron-formation and tuff. The basalt is overlain by a calc-alkalic dacite to rhyolite lapilli-tuff unit and a laterally continuous upper tuff unit of calc-alkalic basalt to andesite. The Mona Formation represents an evolving tholeiitic, mafic shield to mafic-felsic calc-alkalic, mafic to felsic subaqueous volcano. The Deer Lake Peridotite, an ultramafic sill complex that intrudes the Kitchi Formation, is speculatively interpreted as a subvolcanic ultramafic komatiite base of the Mona Formation.

Monthly Catalogue, United States Public Documents

Monthly Catalogue, United States Public Documents
Title Monthly Catalogue, United States Public Documents PDF eBook
Author
Publisher
Pages 1690
Release 1991
Genre Government publications
ISBN

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