Rapid variation in upper-mantle rheology across the San Andreas fault system and Salton Trough, southernmost California, USA

Abstract

Research Article| July 01, 2016 Rapid variation in upper-mantle rheology across the San Andreas fault system and Salton Trough, southernmost California, USA Shahar Barak; Shahar Barak Department of Geophysics, Stanford University, 397 Panama Mall, Stanford, California 94305, USA *Current address: Noble Energy, Houston, Texas 77070, USA. Search for other works by this author on: GSW Google Scholar Simon L. Klemperer Simon L. Klemperer Department of Geophysics, Stanford University, 397 Panama Mall, Stanford, California 94305, USA Search for other works by this author on: GSW Google Scholar Geology (2016) 44 (7): 575–578. https://doi.org/10.1130/G37847.1 Article history received: 28 Feb 2016 rev-recd: 21 May 2016 accepted: 24 May 2016 first online: 02 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 Shahar Barak, Simon L. Klemperer; Rapid variation in upper-mantle rheology across the San Andreas fault system and Salton Trough, southernmost California, USA. Geology 2016;; 44 (7): 575–578. doi: https://doi.org/10.1130/G37847.1 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 We present new shear-wave splitting data showing systematic lateral variations in upper-mantle anisotropy across the plate boundary in southernmost California (USA). Beneath the Peninsular Ranges batholith, fast polarization directions parallel the direction of former Farallon subduction, suggestive of a slab remnant. Near the eastern edge of the batholith, across the Elsinore fault, fast polarization directions change rapidly to align with the direction of San Andreas fault shear. We infer that the Elsinore fault penetrates the entire lithosphere and may represent a future localization of the plate boundary that is migrating west from the San Andreas fault. Beneath the Salton Trough and the Chocolate Mountains region, large splitting times, despite a very thin lithosphere, imply vertical melt pockets in the uppermost mantle aligned in the shear direction. Largest splitting times, ∼1.2 s, are seen closest to the Sand Hills fault that projects southeast from the San Andreas fault. Further east, in the southern Basin and Range province, fast directions align with North America absolute plate motion. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.