atlas of deformed and metamorphosed rocks from proterozoic orogens

Atlas of Deformed and Metamorphosed Rocks from Proterozoic Orogens

Author	: T.R.K. Chetty,Wilbert Kehelpannala
Publisher	: Elsevier
Release Date	: 2021-04-15
ISBN 10	: 9780128179789
Pages	: 400 pages

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Atlas of Deformed and Metamorphosed Rocks from Proterozoic Orogens is a richly illustrated reference book featuring 400 full-color images of varied rock compositions, each with a concise description providing location, lithology, structural fabric, possible deformational history, metamorphic features, and other important geological information. Its relevance and significance in understanding the geological and tectonic history of the region is highlighted by providing relevant key references. The high-grade rocks included in the Atlas are mostly from the regions of Proterozoic orogenic belts. However, some of the regions in these orogenic belts are often covered by sediments, glacial deposits or vegetation, and therefore, inaccessible for scientific research. Atlas of Deformed and Metamorphosed Rocks from Proterozoic Orogens provides a range of lithologies and associated structural features that are captured from well-exposed sections of Proterozoic orogenic belts of India, Sri Lanka, Madagascar, Western Australia, Southern Africa, the Arabian Shield, and Antarctica. The Atlas provides an important source of information and reading for a broad range of earth scientists, graduate and undergraduate students, researchers, academicians and other professionals. This will also be useful for specialists in structural geology, petrology, geochemistry, geochronology, isotope studies, exploration geology, economic geology, and geophysics. Features 400 full-color photographs representing typical lithologies and associated structural and metamorphic features from different Proterozoic orogens Includes line drawings of the photographs for clarity and better understanding Presents regional geologic maps from Proterozoic orogens worldwide

Nature and Style of Deformation in the Foreland of the Early Proterozoic Penokean Orogen, Northern Michigan

Author	: J. S. Klasner,R. W. Ojakangas,Geological Survey (U.S.),G. L. LaBerge
Publisher	: N.A
Release Date	: 1991
ISBN 10	:
Pages	: 22 pages

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Evidence for Early Proterozoic north-verging folding and thrusting in the continental foreland of the Penokean orogen is present in two widely separated areas in northern Michigan. In the eastern part of the exposed orogen, asymmetric to over-turned folds in the Early Proterozoic Michigamme Formation suggest an initial (D1) phase of possibly north verging thin-skinned deformation. A second phase (D2 ) is characterized by a more thick skinned deformation consisting of northward thrusting of Archean gneiss and overlying Early Proterozoic quartzite along ductile thrust faults. Crosscutting shear zones indicate a third phase (D3 ) of deformation involving east- northeast thrusting of Archean gneiss. Thick-skinned deformation D2 and D3 phases include spaced fracture cleavage, kink folds, and lineations in D1, foliation surfaces. Near the west end of the exposed orogen in Michigan, bedding-cleavage relationships in the Early Proterozoic Tyler Formation also indicate northward tectonic transport. These structures, which are interpreted as D1 lie along the north edge of the Archean Puritan batholith and associated Archean greenstone. The north-verging structures in the northern Michigan segment of the Penokean orogen were formed approximately 1,850 Ma during collision of the Wisconsin magmatic terranes with the continental foreland of Michigan, Wisconsin, and Minnesota.