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Detailed three-dimensional structure of the deep crust based on COCORP data in the Cordilleran interior, north-central Washington

1988; Geological Society of America; Volume: 100; Issue: 1 Linguagem: Inglês

10.1130/0016-7606(1988)100 2.3.co;2

1943-2674

W. E. Sanford, Christopher J. Potter, Jack Oliver,

Geological Modeling and Analysis

Research Article| January 01, 1988 Detailed three-dimensional structure of the deep crust based on COCORP data in the Cordilleran interior, north-central Washington WILLIAM E. SANFORD; WILLIAM E. SANFORD 1Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar CHRISTOPHER J. POTTER; CHRISTOPHER J. POTTER 1Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar JACK E. OLIVER JACK E. OLIVER 1Institute for the Study of the Continents, Cornell University, Ithaca, New York 14853 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1988) 100 (1): 60–71. https://doi.org/10.1130/0016-7606(1988)100 2.3.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 WILLIAM E. SANFORD, CHRISTOPHER J. POTTER, JACK E. OLIVER; Detailed three-dimensional structure of the deep crust based on COCORP data in the Cordilleran interior, north-central Washington. GSA Bulletin 1988;; 100 (1): 60–71. doi: https://doi.org/10.1130/0016-7606(1988)100 2.3.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 An unusual opportunity for special processing of selected COCORP data has provided three-dimensional information on deep crustal structure related to Proterozoic rifting, Mesozoic thrusting, and Cenozoic extension in the interior of the United States Cordillera, near the Okanogan Dome, north-central Washington. Using a set of short, intersecting seismic line segments in conjunction with longer regional east-west and north-south seismic lines, we have found dramatic variation vertically in the orientation of structure throughout the crust in this region.A lower crustal block of south-dipping structures lies above a regionally horizontal Moho found at about 34 km depth.This block is ∼13 km thick and is bounded above by a southwest-dipping structure which is discordant to structures both above and below it and is interpreted as a midcrustal thrust formed during Mesozoic to Paleocene convergence. These relationships suggest that the south- dipping lower crustal features were formed prior to, or during, Mesozoic convergence and may be associated either with Proterozoic rifting of the North American continental margin, earlier Proterozoic basement structure, or with a Mesozoic duplex structure formed along a lateral ramp. A zone of relatively few reflections occurs above the mid-crustal thrust and below a highly reflective upper crust and may represent a separate thrust slice in a basement duplex structure. The inferred duplex is cut by east-dipping reflections that project to surface exposures of mylonites and that may be an Eocene(?) normal fault traceable to mid-crustal depths. This duplex structure beneath the Okanogan Dome is analogous to the proposed crustal-scale duplex beneath the Monashee Déecollement exposed in a doubly plunging antiform 150 km to the north in the Shuswap Complex. The three-dimensional analysis, along with the southerly plunge of the antiform, indicates that a thrust at depth just south of the United States-Canadian border may be continuous with the Monashee Déecollement or with the proposed lower thrusts of the Canadian duplex. If so, then by extending the survey north across the international border, a structure deep in the crust may be traceable to the surface. 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.