Download or read book Gold in Early Precambrian Superior Province Plutonic Rocks written by W. J. Wolfe and published by . This book was released on 1976 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gold in Early Precambrian Superior Province Plutonic Rocks written by W. J. Wolfe and published by . This book was released on 1976 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Study conducted to determine whether mineralized and unmineralized plutons differ significantly in gold abundance. Six Early Precambrian intrusions ranging in size from 4-88 sq km and in composition from syenite to granodiorite were selected for a study of gold abundance and distribution. Each of the investigated plutons was randomly sampled at 20-50 sites. At each outcrop site, two representative samples of unweathered rock chips weighing 800- 1200 g were collected about 5-15 m apart. The gold determination was made by a combined atomic absorption spectroscopy and fire assay method.
Download or read book Geology of the Precambrian Superior and Grenville Provinces and Precambian Fossils in North America written by S.B. Lucas and published by Geological Society of America. This book was released on 1998 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains a description of the geology and mineral deposits of the Superior Province of the Canadian Shield, an overview of Grenville Province geology, and a synopsis of Precambrian fossil occurrences in North America. Six large plates include a geological map of Canada, geological map of the Grenville Province, lithotectonic map of the Superior Province, Archean mineral deposit map of the Superior Province, and more.
Download or read book Geological Survey Professional Paper written by and published by . This book was released on 1980 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Precambrian Geology of the United States written by Philip B. King and published by . This book was released on 1976 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summary of Field Work 1978 written by and published by . This book was released on 1978 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Regional Structural Model for Gold Mineralization in the Southern Part of the Archean Superior Province United States written by Paul Kibler Sims and published by . This book was released on 1992 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Canadian segment of the Archean Superior province is a major world source of lode gold. The gold deposits occur in or near regional transcurrent and oblique slip-shear deformation zones that comprise a conjugate set to a northwest- directed compression of the Superior province. These structures provided permeable pathways for the flow of large volumes of auriferous fluid derived from an external source. Historic gold production from the United States segment of the Superior province is modest, but the close similarity in the geologic environment of the United States and Canadian segments suggests that large gold deposits should be present in the U.S.A. An occurrence model largely based on known parameters of gold mineralization in Canada suggests that the greenstone-granite terranes of the Wawa and Wabigoon sub-provinces in the United States are favorable for important gold deposits. The model suggests that gold mineralization took place during or later than the transcurrent faulting and that it took place contemporaneously with emplacement of silica-undersaturated intrusions. The faulting occurred late in the igneous-tectonic history of the Superior province, about 2,690 Ma. Extensive, intense alteration comprising carbonitization, silicification, and sulfidization accompanied the gold mineralization. The relationships between alteration minerals and mineralized veins suggest a close temporal relationship between the alteration and gold mineralization processes. The proposed occurrence model for gold mineralization and the available data suggest that two broad regions of greenstone in the Archean Superior province in north-central United States are particularly favorable for gold deposits: (1) the Upper Peninsula of Michigan, and (2) northeastern Minnesota. The Ishpeming greenstone belt of the Wawa subprovince in Michigan contains the important Ropes deposit and several other known gold occurrences, and the Vermilion district (Wawa subprovince) in northeastern Minnesota contains highly anomalous gold in soils and minor known bedrock occurrences. Transcurrent faults in both areas should be favorable sites for gold mineralization
Download or read book Precambrian Conterminous U S written by John C. Reed, Jr. and published by Geological Society of America. This book was released on 1993 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: This wide-ranging discussion of Precambrian rocks includes contributions from a diverse array of authors actively engaged in investigations of various aspects of U.S. Precambrian geology. Summary discussions by the editors of the five major chapters place these contributions in a logical regional framework.
Download or read book Ontario Geological Survey Miscellaneous Paper written by Ontario. Ministry of Natural Resources and published by . This book was released on 1976 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Archean Crustal Evolution written by K.C. Condie and published by Elsevier. This book was released on 1994-11-11 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: The integration of Tectonics/Geochemistry, up-to-date reviews by leading scientists as well as a broad topical coverage of the Archean, are some of the features of this particular volume. As geochronology has progressed in the last 20 years, the Archean has continued to attract interest. Advancements in the understanding of Archean crustal and mantle evolution have progressed rapidly since the first International Archean Symposium in Western Australia (1970). The landmark for the Archean was the NATO Advanced Study Institute at Leicester (1975). At this meeting the Archean truly "came of age". Investigators from many different disciplines focused their expertise on the early history of the earth. For the first time, the nature of the atmosphere, oceans, and life during the Archean was an important part of an Archean symposium. During the most recent Archean Symposium in Perth in 1990, there was a shift in interest from field and trace element data to the new rapidly evolving high-precision U/Pb geochronology of Archean rocks and to detailed structural studies of both low and high grade Archean terrains. The terrane concept so widely applied to the Phanerozoic was proposed for the Archean Yilgarn Province in Western Australia and is now widely accepted for the Archean (as evident by the articles in this book). Plate tectonics is now widely accepted as the principal process that controls the history of continents and oceans. There are, though, well substantiated differences between Archean and post-Archean rocks that indicate that Archean tectonic regimes must have differed in some respects from modern ones. The question of how and to what degree did Archean plate tectonics differ from modern plate tectonics is treated in many of the chapters of this book. Altogether, the editor has presented a selection of articles that provide a fascinating insight into the latest observations in this field.
Download or read book U S Geological Survey Professional Paper written by and published by . This book was released on 1984 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Early Precambrian Basic Magmatism written by R.P. Hall and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: Basic magmatic rocks make up approximately three-quarters of the crust ofthe present day Earth. Because we can observe and study the volcanic products of present day tectonic regimes comprehensively, we can shed light on ancient tectono-magmatic provinces, and thereby deduce the petrogenesis and evolution of the oldest basic rocks. This is the primary objective of this book. The book was conceived in order to provide a comprehensive review of the basic rocks produced during the first half of the Precambrian, i.e. the Archaean and early Proterozoic, to about 1.8 Ga years ago. Two major questions are addressed. First, what basic magmas were generated during the early Precambrian: were these magmas globally uniform, and to what extent were prevailing tectonic controls and compo sitions analogous to those of the present day? Clearly, this can be answered only by bringing together fundamental information about all relevant basic magmatic events. Second, is there any systematic temporal variation in the nature of basic suites, and what implications might such variations have on our interpretations of early Earth history? Are there important differences between early Archaean, late Archaean, Proterozoic and modern basic magmatic suites? The book uses two approaches to address these questions. Early chapters examine the fundamental characteristics of these basic rocks, whilst later chapters assess regional distribution and development by providing an overview of each major early Precambrian craton.
Download or read book New Publications of the Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1991 with total page 746 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Summary of Field Work by the Ontario Geological Survey written by Ontario Geological Survey and published by . This book was released on 1980 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S Geological Survey Bulletin written by and published by . This book was released on 1983 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S Geological Survey Bulletin written by Paul Kibler Sims and published by . This book was released on 1983 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Precambrian written by and published by . This book was released on 1963 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
