Overview of the COCORP 40°N Transect, western United States: The fabric of an orogenic belt

Abstract

Research Article| March 01, 1987 Overview of the COCORP 40°N Transect, western United States: The fabric of an orogenic belt R. W. ALLMENDINGER; R. W. ALLMENDINGER 1Institute for the Study of the Continents and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar T. A. HAUGE; T. A. HAUGE 2Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar E. C. HAUSER; E. C. HAUSER 2Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar C. J. POTTER; C. J. POTTER 2Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar S. L. KLEMPERER; S. L. KLEMPERER 3Institute for the Study of the Continents and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar K. D. NELSON; K. D. NELSON 4Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar P. KNUEPFER; P. KNUEPFER 4Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar J. OLIVER J. OLIVER 5Institute for the Study of the Continents and Department of Geological Sciences, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1987) 98 (3): 308–319. https://doi.org/10.1130/0016-7606(1987)98<308:OOTCNT>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. W. ALLMENDINGER, T. A. HAUGE, E. C. HAUSER, C. J. POTTER, S. L. KLEMPERER, K. D. NELSON, P. KNUEPFER, J. OLIVER; Overview of the COCORP 40°N Transect, western United States: The fabric of an orogenic belt. GSA Bulletin 1987;; 98 (3): 308–319. doi: https://doi.org/10.1130/0016-7606(1987)98<308:OOTCNT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The COCORP 40°N Transect of the Cordillera of the western United States crosses tectonic features ranging in age from Proterozoic to Recent and provides an acoustic cross-section of a complex orogen affected by extension, compression, magmatism, and terrane accretion. The key features of the transect, centered on the Basin and Range Province, include (1) asymmetric seismic fabrics in the Basin and Range, including west-dipping reflections in the eastern part of the province and predominantly subhorizontal ones in the west; (2) a pronounced reflection Moho at 30 ± 2 km and locally as deep as 34 km in the Basin and Range with no clear sub-Mono reflections; and (3) complex-dipping reflections and diffractions locally as deep as 48 km in the Colorado Plateau and Sierra Nevada. The eastern part of the transect, shot above known and inferred Precambrian crystalline basement, probably records features related to the entire history of the orogen, locally perhaps as old as 1800 Ma. In this region, major paleotectonic features probably controlled subsequent structural development. In title western half of the transect, however, most reflectors are probably no older than Mesozoic. Within the Basin and Range Province, there appears to be a strong Cenozoic overprint that is characterized by asymmetric half-grabens, low-angle normal faults, and a pervasive subhorizontal system of reflections in the lower crust; no one model of intracontinental extension is universally applicable. Processes that produce or are accompanied by thermal anomalies (magmatism, enhanced ductility, and extension) appear to be essential in developing a highly layered lower crust. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.