Constraints on the metamorphic evolution of the eastern Himalayan syntaxis from geochronologic and petrologic studies of Namche Barwa

Research Article| March 01, 2009 Constraints on the metamorphic evolution of the eastern Himalayan syntaxis from geochronologic and petrologic studies of Namche Barwa Amanda L. Booth; Amanda L. Booth † 1Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, P.O. Box 755860, Fairbanks, Alaska 99775, USA †E-mail: ffalb@uaf.edu Search for other works by this author on: GSW Google Scholar C. Page Chamberlain; C. Page Chamberlain 1Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, P.O. Box 755860, Fairbanks, Alaska 99775, USA Search for other works by this author on: GSW Google Scholar William S.F. Kidd; William S.F. Kidd 2Department of Earth and Atmospheric Sciences, University at Albany, Albany, New York 12222, USA Search for other works by this author on: GSW Google Scholar Peter K. Zeitler Peter K. Zeitler 3Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Amanda L. Booth † 1Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, P.O. Box 755860, Fairbanks, Alaska 99775, USA C. Page Chamberlain 1Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, P.O. Box 755860, Fairbanks, Alaska 99775, USA William S.F. Kidd 2Department of Earth and Atmospheric Sciences, University at Albany, Albany, New York 12222, USA Peter K. Zeitler 3Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA †E-mail: ffalb@uaf.edu Publisher: Geological Society of America Received: 17 May 2006 Revision Received: 21 Mar 2008 Accepted: 29 Mar 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2009 Geological Society of America GSA Bulletin (2009) 121 (3-4): 385–407. https://doi.org/10.1130/B26041.1 Article history Received: 17 May 2006 Revision Received: 21 Mar 2008 Accepted: 29 Mar 2008 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Amanda L. Booth, C. Page Chamberlain, William S.F. Kidd, Peter K. Zeitler; Constraints on the metamorphic evolution of the eastern Himalayan syntaxis from geochronologic and petrologic studies of Namche Barwa. GSA Bulletin 2009;; 121 (3-4): 385–407. doi: https://doi.org/10.1130/B26041.1 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 The eastern Himalayan syntaxis is host to the actively deforming metamorphic massif, Namche Barwa. This massif has experienced a complex history of uplift and deformation, influenced by intense fluvial erosion associated with the Yarlung Tsangpo. Here we present new thermobarometric and geochronologic information on metamorphic rocks from the Namche Barwa–Gyala Peri region. Pressure-temperature data are combined with U-Th-Pb ages of monazite and titanite in an effort to trace the metamorphic evolution of the eastern Himalaya. Metapelitic rocks containing garnet-biotite-plagioclase assemblages yield peak metamorphic pressures and temperatures of 10–14 kbar and 700–900 °C in the structural core of the massif. There is a distinct metamorphic break across the Namula thrust, separating high-grade rocks to the north from lower grade rocks to the south. Ion microprobe monazite and titanite ages of 3–10 Ma indicate that timing of metamorphism is roughly coincident with the age of granitic melt production (<10 Ma) as well as the onset of rapid denudation. In-situ ages determined from monazites included in garnet show that they grew over a period of several million years (6.4 ± 0.3 Ma to 11.3 ± 0.2 Ma) and during a pressure decrease of ~5 kbar. These data suggest that high-grade metamorphism and anatexis is a phenomenon that has been operative at Namche Barwa since at least the mid-Miocene. Geodynamic models for the evolution of Namche Barwa must therefore account for these features. We conclude that our data most closely fit the tectonic aneurysm model, based on distinct spatial correlations between pressure-temperature (P-T) conditions, age of metamorphism, and erosion by the Tsangpo. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.