Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis

Research Article| April 26, 2018 Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis Yu-Ping Chiu; Yu-Ping Chiu 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Meng-Wan Yeh; Meng-Wan Yeh † 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan2Center for General Education, National Taiwan Normal University, Taipei, Taiwan †Corresponding author: marywyeh@ntnu.edu.tw. Search for other works by this author on: GSW Google Scholar Kuang-Hsuan Wu; Kuang-Hsuan Wu 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Tung-Yi Lee; Tung-Yi Lee 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Ching-Hua Lo; Ching-Hua Lo 3Department of Geosciences, National Taiwan University, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Sun-Lin Chung; Sun-Lin Chung 3Department of Geosciences, National Taiwan University, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Yoshiyuki Iizuka Yoshiyuki Iizuka 4Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Author and Article Information Yu-Ping Chiu 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Meng-Wan Yeh † 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan2Center for General Education, National Taiwan Normal University, Taipei, Taiwan Kuang-Hsuan Wu 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Tung-Yi Lee 1Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Ching-Hua Lo 3Department of Geosciences, National Taiwan University, Taipei, Taiwan Sun-Lin Chung 3Department of Geosciences, National Taiwan University, Taipei, Taiwan Yoshiyuki Iizuka 4Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan †Corresponding author: marywyeh@ntnu.edu.tw. Publisher: Geological Society of America Received: 23 Mar 2017 Revision Received: 18 Jan 2018 Accepted: 09 Mar 2018 First Online: 26 Apr 2018 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2018 Geological Society of America GSA Bulletin (2018) 130 (9-10): 1675–1696. https://doi.org/10.1130/B31811.1 Article history Received: 23 Mar 2017 Revision Received: 18 Jan 2018 Accepted: 09 Mar 2018 First Online: 26 Apr 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Yu-Ping Chiu, Meng-Wan Yeh, Kuang-Hsuan Wu, Tung-Yi Lee, Ching-Hua Lo, Sun-Lin Chung, Yoshiyuki Iizuka; Transition from extrusion to flow tectonism around the Eastern Himalaya syntaxis. GSA Bulletin 2018;; 130 (9-10): 1675–1696. doi: https://doi.org/10.1130/B31811.1 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 Two contradictory plate-kinematic models, (1) collision extrusion and (2) mid- to lower-crustal-level flow, have been proposed for inducing crustal deformation surrounding the eastern Tibetan Plateau in response to the Cenozoic collision of India-Eurasia. A hybrid tectonic model indicating extrusion followed by crustal flow is established by new structural, petrological, and geochronological data obtained from the Gaoligong shear zone in western Yunnan, China. The 40Ar/39Ar ages for muscovite (34–31 Ma), biotite (23 Ma), and K-feldspar (33–21 Ma) mineral separates from the Gaoligong group, and a matrix crosscutting quartzofeldspathic dike produce a cooling path. By interlinking the synkinematic metamorphic conditions with the reconstructed cooling path, we find that the temperature dropped from 550 °C around ca. 34 Ma to 350 °C at ca. 32 Ma, and dropped again to 275 °C around ca. 22 Ma. The timing and kinematic mechanism of four ductile deformation events, followed by brittle deformation, is deciphered. The earliest D1 event deformed the Early Cretaceous granite (zircon U-Pb ages of 118–78 Ma), forming WNW-ESE–striking upright folds during the closure of the Neo-Tethyan ocean. The D2 event was associated with large-scale eastward thrusting and folding with top-to-the-N/NE sense of shear under upper-amphibolite-facies conditions between 50 and 35 Ma due to India-Eurasia continent-continent collision. D3 formed moderate NE-dipping, NW-SE–striking, left-lateral shear zones that accommodated the southeastward extrusion of Indochina around 35–28 Ma. The sinistral sense of shear S/C fabrics defined by muscovite folia with foliation-bounded myrmekite indicates that deformation occurred under middle- to lower-amphibolite-facies metamorphic conditions. The 28 Ma to 15 Ma steep N-S–trending, right-lateral Gaoligong shear belt (D4) is the dominant structural feature in this region. Chloritization of biotite and boudinaged sillimanite along S/C2 fabrics indicate that the crystalline rocks retrograded from amphibolite-facies into greenschist-facies conditions. This coincided with clockwise cataclastic flow around the Eastern Himalaya syntaxis due to gravitational collapse after delamination of the thickened Tibetan Plateau. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.