Isotopic evidence for preservation of Cordilleran lithospheric mantle during the Sevier-Laramide orogeny, western United States

Research Article| August 01, 1993 Isotopic evidence for preservation of Cordilleran lithospheric mantle during the Sevier-Laramide orogeny, western United States Richard F. Livaccari; Richard F. Livaccari 1Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 Search for other works by this author on: GSW Google Scholar Frank V. Perry Frank V. Perry 1Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 Search for other works by this author on: GSW Google Scholar Author and Article Information Richard F. Livaccari 1Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 Frank V. Perry 1Department of Earth & Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1993) 21 (8): 719–722. https://doi.org/10.1130/0091-7613(1993)021<0719:IEFPOC>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Richard F. Livaccari, Frank V. Perry; Isotopic evidence for preservation of Cordilleran lithospheric mantle during the Sevier-Laramide orogeny, western United States. Geology 1993;; 21 (8): 719–722. doi: https://doi.org/10.1130/0091-7613(1993)021<0719:IEFPOC>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 SocietyGeology Search Advanced Search Abstract It has been inferred that Sevier-Laramide flat subduction imparted a large basal shear traction force to the overriding North American plate, resulting in Laramide Rocky Mountain foreland deformation and significant thinning of Cordilleran lithosphere. Additional inferred consequences include regional refrigeration of Cordilleran crust and suppression of synorogenic extensional collapse. Nd isotopic data from Cenozoic mafic volcanic rocks indicate that normal-thickness lithospheric mantle was preserved beneath the Cordilleran craton from Precambrian to late Cenozoic time. Therefore, Cordilleran lithosphere was not thinned significantly, and extensional collapse of orogenically thickened crust was not suppressed by refrigeration. Analogy with the South American Cordillera suggests that flat subduction does not apply significant shear stress to the base of overriding plate lithosphere beyond the fore-arc region and therefore does not mechanically thin overriding plate lithosphere (except in the fore-arc region). The principal result of flat subduction was enhanced mechanical coupling between the underriding and overriding plates along the fore-arc region. This increased the horizontal end load, due to relative plate convergence, placed on the North American plate. Horizontal end-load stress was transmitted laterally across both (1) a hinterland that had attained maximum crustal thickness and (2) the rigid Colorado Plateau into the Laramide Rocky Mountain foreland. Early Tertiary waning of plate-convergence rates then allowed radial extensional collapse of the southern Cordilleran region to drive the Colorado Plateau block northward, resulting in late Laramide Rocky Mountain foreland deformation. 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.