The Malari leucogranite, Garhwal Himalaya, northern India: Chemistry, age, and tectonic implications

Abstract

Research Article| November 01, 2010 The Malari leucogranite, Garhwal Himalaya, northern India: Chemistry, age, and tectonic implications Himanshu K. Sachan; Himanshu K. Sachan 1Wadia Institute of Himalayan Geology, 33 Gen Mahadev Singh Road, Dehra Dun 248001, India Search for other works by this author on: GSW Google Scholar Matthew J. Kohn; Matthew J. Kohn † 2Department of Geosciences, Boise State University, Boise, Idaho 83725, USA †E-mail: mattkohn@boisestate.edu Search for other works by this author on: GSW Google Scholar Anubhooti Saxena; Anubhooti Saxena 1Wadia Institute of Himalayan Geology, 33 Gen Mahadev Singh Road, Dehra Dun 248001, India Search for other works by this author on: GSW Google Scholar Stacey L. Corrie Stacey L. Corrie 2Department of Geosciences, Boise State University, Boise, Idaho 83725, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2010) 122 (11-12): 1865–1876. https://doi.org/10.1130/B30153.1 Article history received: 12 Aug 2009 rev-recd: 10 Nov 2009 accepted: 27 Nov 2009 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Himanshu K. Sachan, Matthew J. Kohn, Anubhooti Saxena, Stacey L. Corrie; The Malari leucogranite, Garhwal Himalaya, northern India: Chemistry, age, and tectonic implications. GSA Bulletin 2010;; 122 (11-12): 1865–1876. doi: https://doi.org/10.1130/B30153.1 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 In the Garhwal region, India, the Malari leucogranite cuts the South Tibetan detachment system, a large-scale normal fault system at the top of the High Himalaya. The leucogranite crosscuts ductile normal-sense shear fabrics and has experienced relatively little subsolidus brittle deformation or alteration. Its relatively evolved bulk chemical composition, high Rb/Sr ratio, and normative corundum indicate a (meta)sedimentary source, likely the underlying Greater Himalayan sequence. Zircon U-Pb ages, collected by laser-ablation inductively coupled plasma–mass spectrometry (ICP-MS) and corrected for initial U/Th disequilibrium, indicate emplacement at 19.0 ± 0.5 Ma. Thus, ductile normal shear on the South Tibetan detachment system must have ceased by 19 Ma. Studies elsewhere in the Himalaya suggest initiation of South Tibetan detachment system ductile movement not earlier than 24 Ma, and likely ca. 22 Ma. The short duration of extension (≤5 and likely ∼3 m.y.) and early cessation contrast with channel-flow models that predict long-duration ductile normal shear, and large displacements after ca. 20 Ma. Observations are instead better explained by critical taper models, in which internal weakening of the wedge, likely from partial melting, caused a brief interval of flattening and ductile extension in the rear of the wedge. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.