Magma ponding in the Karakoram shear zone, Ladakh, NW India

Abstract

Research Article| January 01, 2009 Magma ponding in the Karakoram shear zone, Ladakh, NW India Roberto F. Weinberg; Roberto F. Weinberg † 1School of Geosciences, Monash University, Clayton, VIC 3800, Australia †E-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Geordie Mark; Geordie Mark 1School of Geosciences, Monash University, Clayton, VIC 3800, Australia *Present address: Haywood Securities Inc., 400 Burrard Street, Vancouver, British Columbia V6C 3A6, Canada. Search for other works by this author on: GSW Google Scholar Henning Reichardt Henning Reichardt 1School of Geosciences, Monash University, Clayton, VIC 3800, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Roberto F. Weinberg † 1School of Geosciences, Monash University, Clayton, VIC 3800, Australia Geordie Mark *Present address: Haywood Securities Inc., 400 Burrard Street, Vancouver, British Columbia V6C 3A6, Canada. 1School of Geosciences, Monash University, Clayton, VIC 3800, Australia Henning Reichardt 1School of Geosciences, Monash University, Clayton, VIC 3800, Australia †E-mail: [e-mail] Publisher: Geological Society of America Received: 04 Nov 2007 Revision Received: 12 Feb 2008 Accepted: 29 Feb 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2008 Geological Society of America GSA Bulletin (2009) 121 (1-2): 278–285. https://doi.org/10.1130/B26358.1 Article history Received: 04 Nov 2007 Revision Received: 12 Feb 2008 Accepted: 29 Feb 2008 First Online: 02 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 Roberto F. Weinberg, Geordie Mark, Henning Reichardt; Magma ponding in the Karakoram shear zone, Ladakh, NW India. GSA Bulletin 2009;; 121 (1-2): 278–285. doi: https://doi.org/10.1130/B26358.1 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 Granitic melt migration and pluton emplacement are commonly closely associated with transcurrent shear zones. The processes that link granites to shear zones are not yet fully understood. The dextral-transpressive Karakoram shear zone in Ladakh, NW India, exposes anatectic rocks where synkinematic melt migration and ponding at kilometer scale were controlled by competency contrasts. Metasedimentary rocks and a dominantly granodioritic calc-alkaline intrusion underwent fluid-present partial melting at upper-amphibolite facies to produce leucogranite sheets and irregular intrusive masses dated at 21–14 Ma. Leucogranitic magmas ponded in the low-pressure strain shadow of the competent granodioritic calc-alkaline pluton, giving rise to (a) migmatitic rocks that are pervaded by irregular leucogranite intrusions at a scale of meters or tens of meters, and (b) the growth of the Tangtse pluton, a kilometer-scale sheeted complex. Thus, magmas accumulated during shearing and anatexis in a low-pressure strain shadow within the Karakoram shear zone. This magma provided a readily available magma source that could have been tapped to feed larger plutons at shallower levels by modifications in the pressure distribution accompanying changes in shear zone geometry and kinematics. We conclude that shear zones tapping anatectic regions act as magma pumps, creating and destroying magma traps at depth as they evolve, and leading to incremental magma addition to upper-crustal plutons. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.