Direct shear fabric dating constrains early Oligocene onset of the South Tibetan detachment in the western Nepal Himalaya

Abstract

Research Article| June 01, 2016 Direct shear fabric dating constrains early Oligocene onset of the South Tibetan detachment in the western Nepal Himalaya Renaud Soucy La Roche; Renaud Soucy La Roche 1Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada Search for other works by this author on: GSW Google Scholar Laurent Godin; Laurent Godin 1Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada Search for other works by this author on: GSW Google Scholar John M. Cottle; John M. Cottle 2Department of Earth Science, University of California–Santa Barbara, Santa Barbara, California 93106-9630, USA Search for other works by this author on: GSW Google Scholar Dawn A. Kellett Dawn A. Kellett 3Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Renaud Soucy La Roche 1Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada Laurent Godin 1Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada John M. Cottle 2Department of Earth Science, University of California–Santa Barbara, Santa Barbara, California 93106-9630, USA Dawn A. Kellett 3Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Publisher: Geological Society of America Received: 03 Feb 2016 Revision Received: 01 Apr 2016 Accepted: 02 Apr 2016 First Online: 09 Mar 2017 Online Issn: 1943-2682 Print Issn: 0091-7613 © 2016 Geological Society of America Geology (2016) 44 (6): 403–406. https://doi.org/10.1130/G37754.1 Article history Received: 03 Feb 2016 Revision Received: 01 Apr 2016 Accepted: 02 Apr 2016 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Renaud Soucy La Roche, Laurent Godin, John M. Cottle, Dawn A. Kellett; Direct shear fabric dating constrains early Oligocene onset of the South Tibetan detachment in the western Nepal Himalaya. Geology 2016;; 44 (6): 403–406. doi: https://doi.org/10.1130/G37754.1 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 A newly identified and dated segment of the South Tibetan detachment in the Karnali klippe, western Nepal Himalaya, constrains initiation of mid-crustal tectonically driven exhumation to the early Oligocene. The folded top-to-the-northeast high-temperature (∼600 °C) shear zone separates amphibolite-facies rocks with a ca. 36–30 Ma prograde metamorphic history in the footwall from weakly to non-metamorphosed upper crustal rocks in the hanging wall. In situ dating of syn-kinematic–post-metamorphic peak monazite indicates that the base of the shear zone was active from ca. 30–29 to <24 Ma, and a post-deformation muscovite cooling age implies that ductile shearing had ceased by ca. 19 Ma. Deformation along the South Tibetan detachment in western Nepal was thus synchronous with thrust-sense shearing along the lower boundary of a zone of migmatitic rocks, compatible with tectonic models involving mid-crustal channelized flow during the Oligocene. Along with other published data from the Himalayan range, this suggests that the South Tibetan detachment actively exhumed the middle crust for almost 20 m.y. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.