Download or read book The Metamorphic and Structural Evolution of the Davis Peak Area Northern Park Range Colorado written by Joshua T. Sigler and published by ProQuest. This book was released on 2008 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Davis Peak area is a ~100 km 2 part of the northern Park Range, Colorado, comprised of a heterogeneous suite of high-grade metamorphic and associated ultramafic/mafic-to-felsic intrusive rocks. These rocks are part of an extensive province of Paleoproterozoic island-arc terranes exposed in basement-involved uplifts that extend southward from the Cheyenne belt in southeastern Wyoming. Modern interpretations contend that the accretion of these terranes began along the Cheyenne belt with the ~1.78-Ga accretion of the Green Mountain arc followed by accretion of the ~1.75-Ga Rawah arc to the southern margin of the Green Mountain arc along the Farwell Mountain-Lester Mountain suture zone. Rocks of the northernmost Park Range are commonly interpreted as part of the Green Mountain arc, however, the affinity of these rocks has not been studied in detail. This study has employed a broad range of techniques including detailed field mapping, petrographic analysis, thermobarometry, and radiometric dating to determine the affinity of high-grade metamorphic rocks and associated intrusive rocks in the Davis Peak area. Detailed geologic field mapping reveals that the Davis Peak area is primarily comprised of a heterogeneous suite of metamorphic rocks (Big Creek gneiss) that have been pervasively intruded by ultramafic/mafic-to-felsic plutonic rocks. This diverse assemblage of metamorphic and igneous rocks is broadly equivalent to lithologic units recognized in the Sierra Madre (southeastern Wyoming), which are interpreted as part of the Green Mountain arc. Thus this correlation suggests that Precambrian rocks of the Davis Peak area are also part of the Green Mountain arc. The penetrative fabric in the Davis Peak area is chiefly a northeast-southwest-striking foliation that has been locally overprinted by younger ductile-to-brittle deformations. This structural history is basically comparable to the deformational history manifested in the Precambrian rocks of the Sierra Madre and Medicine Bow Mountains. This potential correlation suggests that regionally extensive ductile deformation dated at ~1.75 Ga and late cataclastic deformation dated at ~1.6 Ga have affected the entire Green Mountain arc including the northern Park Range. The Big Creek gneiss is characterized by metapelitic garnet-biotite-sillimanite paragneisses, metavolcanic (sometimes garnet-bearing) amphibolites, and intercalated subordinate calc-silicate rocks. Thermobarometric results from these rocks suggest that the Davis Peak area experienced metamorphic P-T conditions of ~6 kb and 675 °C followed by a period of decompression at ~4 kb and ~650 °C. Several U-Pb radiometric ages from metamorphic monazite and titanite have been used to directly date metamorphism and suggest that two phases of metamorphism have affected the Davis Peak area at ~1752 Ma and ~1615-1565 Ma. Microstructural and compositional evidence from high-grade metamorphic rocks suggest that evidence for ~1752-Ma metamorphism is only locally preserved and that thermobarometric results chiefly reflect tectonothermal events at ~1.6 Ga. Furthermore, non-penetrative epidote-bearing slickensided surfaces in the Davis Peak area are comparable with similar surfaces dated at ~1.6 Ga associated with the Cheyenne belt thereby suggesting that late deformation and metamorphism in the Davis Peak area continued under greenschist-facies conditions. Additionally, thermobarometric results from this study are strikingly similar to results obtained south of the proposed Farwell Mountain-Lester Mountain suture zone suggesting that the proposed break in metamorphic grade across this boundary may not exist. If this conclusion is correct, it requires a revised tectonic scenario for this part of the Colorado province.
Download or read book Proterozoic Metamorphic and Tectonic Evolution of the Northern Colorado Front Range written by Meghan Hodgins and published by . This book was released on 1997 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Publications of the Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1984 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Publications of the U S Geological Survey written by and published by . This book was released on 1984 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geological Survey Professional Paper written by and published by . This book was released on 1982 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1989 with total page 984 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geological Survey Professional Paper written by Geological Survey (U.S.) and published by . This book was released on 1978 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bibliography and Index of the Geology and Mineral Resources of Washington 1963 1980 written by Connie Manson and published by . This book was released on 1983 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Tectonic Setting and Origin of Cretaceous Batholiths within the North American Cordillera written by Robert S. Hildebrand and published by Geological Society of America. This book was released on 2017-10-03 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Special Paper, Hildebrand and Whalen present a big-picture, paradigm-busting synthesis that examines the tectonic setting, temporal relations, and geochemistry of many plutons within Cretaceous batholithic terranes of the North American Cordillera. In addition to their compelling tectonic synthesis, they argue that most of the batholiths are not products of arc magmatism as commonly believed, but instead were formed by slab failure during and after collision. They show that slab window and Precambrian TTG suites share many geochemical similarities with Cretaceous slab failure rocks. Geochemical and isotopic data indicate that the slab failure magmas were derived dominantly from the mantle and thus have been one of the largest contributors to growth of continental crust. The authors also note that slab failure plutons emplaced into the epizone are commonly associated with Cu-Au porphyries, as well as Li-Cs-Ta pegmatites.
Download or read book U S Geological Survey Professional Paper written by and published by . This book was released on 1974 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Special Publication written by and published by . This book was released on 1994 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Special Publication written by Montana Bureau of Mines and Geology and published by . This book was released on 1994 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geologic Literature on North America 1785 1918 written by John Milton Nickles and published by . This book was released on 1924 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bulletin Division of Geology and Earth Resources written by Washington (State). Division of Geology and Earth Resources and published by . This book was released on 1983 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bibliography and Index of Colorado Geology written by and published by . This book was released on 1984 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Broken Land written by Frank DeCourten and published by . This book was released on 2003 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The desert may seem timeless from within the Yellow Circle tonight, but the permanence of the surrounding landscape is only an illusion. Even the land is alive here, constantly changing and evolving as do all living things. Nothing here is 'finished.' Everything around us--the plants, the animals, the rocks, and the terrain itself--is in the process of becoming something else. And, of course, so are we. None of us around the campfire tonight are the same people we were yesterday, or will be tomorrow."--from the book The Broken Land surveys the geological phenomena of the magnificent Great Basin landscape of western Utah, Nevada, eastern California, and adjacent regions. Each chapter focuses on a locality or area that provides insight into the deep history of one of North America's most remote regions--one of its continental margins. It is the only book available covering the geology of the entire Great Basin. Written for anyone with a casual to serious interest in natural history, The Broken Land conveys Frank DeCourten's awe at the story written in the rock of the basin.
