Precambrian Crustal Blocks in Minnesota

Precambrian Crustal Blocks in Minnesota PDF Author: S. R. Hemming
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 24

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Book Description
Sm-Nd survey of Precambrian granitic and metasedimentary rocks collected from several geophysically defined blocks in central Minnesota confirms the presence of some fundamental geologic boundaries previously mapped on the basis of structure. The Malmo discontinuity an Early Proterozoic structure separates the Archean Minnesota River Valley ter- ranes from an Early Proterozoic (Penokean magmatic) terrane and the McGrath Gneiss dome of east-central Minnesota North of this boundary, the Penokean fold-and-thrust belt can be divided into fault-bounded terranes that were assembled during the Penokean orogeny. Each terrane within the study area has distinct crust formation ages.

Precambrian Crustal Blocks in Minnesota

Precambrian Crustal Blocks in Minnesota PDF Author: S. R. Hemming
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 24

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Book Description
Sm-Nd survey of Precambrian granitic and metasedimentary rocks collected from several geophysically defined blocks in central Minnesota confirms the presence of some fundamental geologic boundaries previously mapped on the basis of structure. The Malmo discontinuity an Early Proterozoic structure separates the Archean Minnesota River Valley ter- ranes from an Early Proterozoic (Penokean magmatic) terrane and the McGrath Gneiss dome of east-central Minnesota North of this boundary, the Penokean fold-and-thrust belt can be divided into fault-bounded terranes that were assembled during the Penokean orogeny. Each terrane within the study area has distinct crust formation ages.

Precambrian Crustal Blocks in Minnesota--neodymium Isotope Evidence from Basement and Metasedimentary Rocks

Precambrian Crustal Blocks in Minnesota--neodymium Isotope Evidence from Basement and Metasedimentary Rocks PDF Author: S. R. Hemming
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 15

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Book Description


U.S. Geological Survey Bulletin

U.S. Geological Survey Bulletin PDF Author:
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 372

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U.S. Geological Survey Bulletin

U.S. Geological Survey Bulletin PDF Author: Paul Kibler Sims
Publisher:
ISBN:
Category : Faults (Geology)
Languages : en
Pages : 268

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Book Description
The Early Proterozoic Michigamme Formation of northern Michigan was deposited in the southeastern part of the Animikie basin. The formation conformably overlies the Goodrich Quartzite and comprises three widespread members a lower member of thin-bedded shale, siltstone, and sandstone; the Bijiki Iron-formation Member; and an upper member of tur- biditic graywacke, siltstone, and mudstone and a few local members. The Goodrich Quartzite is interpreted as having been deposited in a tidally influenced shallow marine environ- ment. The lower member of the Michigamme is interpreted as having been deposited in a tidally influenced environment, the iron-formation member as having been deposited below wave base in somewhat deeper water, and the upper member as having been deposited in still deeper water with turbidity currents being a major depositional mechanism. Several lines of evidence including paleocurrents, paleo- geographic setting, and neodymium isotopes suggest that the graywacke of the southern part of the outcrop area was derived from the south (Early Proterozoic Wisconsin magmatic terranes, Archean miniplates, and older Early Proterozoic sedimentary units formed on the continental margin), and that the graywacke in the northern area was derived from an Archean terrane to the north. The tectonic model that best fits the available data is a northward-migrating foreland basin.

New Publications of the Geological Survey

New Publications of the Geological Survey PDF Author: Geological Survey (U.S.)
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 428

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New Publications of the U.S. Geological Survey

New Publications of the U.S. Geological Survey PDF Author: Geological Survey (U.S.)
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 156

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Archean to Anthropocene

Archean to Anthropocene PDF Author: James D. Miller
Publisher: Geological Society of America
ISBN: 0813700248
Category : Science
Languages : en
Pages : 593

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Great Lakes Rocks

Great Lakes Rocks PDF Author: Stephen E Kesler
Publisher: University of MICHIGAN REGIONAL
ISBN: 0472053809
Category : Science
Languages : en
Pages : 369

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Book Description
The geologic story of the Great Lakes region is one of the most remarkable of any place on Earth. Great Lakes Rocks takes readers on this fascinating journey through geologic history, beginning with an investigation of the surface features—the hills and valleys, waterfalls and caves, and the Great Lakes themselves—that we encounter on a daily basis. From there the book digs deeper into the past, and readers learn about the amazing techniques geologists have used to reconstruct the events that shaped this region millions and even billions of years before humans set foot on Earth. Throughout, the book gives special attention to the link between the region’s geology and its modern history, including the impacts of geology on settlement patterns as well as the development of industries and the present-day economy. Other discussed topics include natural hazards that are geologic in nature, including earthquakes, floods, landslides, and coastal erosion, as well as information on rocks, minerals, and ancient life seen in fossils. Written for nonspecialist readers, this book provides a detailed but easy-to-follow introduction to the geology of the Great Lakes region, and it is an ideal fit for introductory geology courses, including those aimed at nonscience majors.

Publications of the Geological Survey

Publications of the Geological Survey PDF Author: Geological Survey (U.S.)
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 452

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Guide to USGS Publications

Guide to USGS Publications PDF Author:
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 1660

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Book Description