Tectonic evolution of the Himalayan thrust belt in western Nepal: Implications for channel flow models

Abstract

Research Article| July 01, 2006 Tectonic evolution of the Himalayan thrust belt in western Nepal: Implications for channel flow models Delores M. Robinson; Delores M. Robinson 1Department of Geological Sciences, University of Alabama, Tuscaloosa, Alabama 35487 USA Search for other works by this author on: GSW Google Scholar Peter G. DeCelles; Peter G. DeCelles 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Peter Copeland Peter Copeland 3Department of Geosciences, University of Houston, Houston, Texas 77204, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Delores M. Robinson 1Department of Geological Sciences, University of Alabama, Tuscaloosa, Alabama 35487 USA Peter G. DeCelles 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Peter Copeland 3Department of Geosciences, University of Houston, Houston, Texas 77204, USA Publisher: Geological Society of America Received: 10 Oct 2005 Revision Received: 11 Jan 2006 Accepted: 05 Feb 2006 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2006) 118 (7-8): 865–885. https://doi.org/10.1130/B25911.1 Article history Received: 10 Oct 2005 Revision Received: 11 Jan 2006 Accepted: 05 Feb 2006 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Delores M. Robinson, Peter G. DeCelles, Peter Copeland; Tectonic evolution of the Himalayan thrust belt in western Nepal: Implications for channel flow models. GSA Bulletin 2006;; 118 (7-8): 865–885. doi: https://doi.org/10.1130/B25911.1 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 SocietyGSA Bulletin Search Advanced Search Abstract We present a new geologic map of western Nepal and three balanced regional cross sections in the Himalayan thrust belt. The minimum shortening between the South Tibetan detachment and the Main Frontal thrust is 485–743 km and suggests that total Himalayan shortening may exceed 900 km. All rocks involved in the thrust belt are of upper crustal affinity, implying that a comparable length of Indian lower crust and mantle lithosphere was subducted beneath Tibet. Major structural features are the Subhimalayan thrust system, Lesser Himalayan imbricate zone, Dadeldhura thrust sheet, Lesser Himalayan duplex, Ramgarh thrust sheet, Main Central thrust sheet, and a north-dipping normal-sense shear zone, possibly related to the South Tibetan detachment. These structures are continuous along the entire Nepalese portion of the Himalayan thrust belt. New 40Ar/39Ar ages from the Ramgarh thrust zone, Greater Himalayan rocks, and the lower part of the Tethyan sequence support a kinematic model in which major thrust systems in Nepal propagated southward from early Miocene time onward. The geometry and kinematic history of the thrust belt in western Nepal are not compatible with recent models for southward ductile extrusion of Greater Himalayan rocks in a mid-crustal channel. Instead, the thrust belt in western Nepal behaved like a typical forward propagating thrust system, involving unmetamorphosed, brittlely deformed rocks in its frontal part and ductilely deformed, higher-grade metamorphic rocks in its hinterland region. Although our results do not support published versions of the channel flow model, they provide additional geological and geo-chronological data that will assist future attempts to develop geodynamic models for the Himalayan-Tibetan orogenic system. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.