Abstract

Info

Title:: Zircon U-Pb and Biotite 40Ar-39Ar Ages of Muztag Pluton in West Kunlun and Their Geological Significance

Author(s):: LIU Zheng-fu; LI Qiu-gen; WANG Zong-qi; TANG Hao-shu; CHEN Yan-jing; ZHU Jie; XIAO Bing; 1. Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education, Peking University, Beijing 100871, China; 2. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China; 3. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China

Keywords:: geochemistry; zircon U-Pb age; 40Ar-39Ar age; Late Triassic; Late Miocene; uplift; West Kunlun orogenic belt

Abstract:: As a key tectonic regime of the subduction and closure of Paleo-Tethys Ocean, the West Kunlun orogenic belt has great significance in the study on the tectonicthermal history of Paleo-Tethys Ocean. Moreover, it has close connection with the tectonic and climatic evolution of Tibetan Plateau and Tarim Basin. In order to reveal the evolution history of Muztag pluton in the northwest section of West Kunlun orogenic belt, several isotopic characteristics of zircon U-Pb ages and biotite ⁴⁰Ar-³⁹Ar ages of melanocratic enclaves hosted in it were discussed. The zircon U-Pb isotopic analysis returns a weighted average U-Pb age of (218.8±1.9)Ma, which is interpreted as the crystallization age of the pluton. Combined with regional geological data, it is inferred that Muztag pluton emplaces in an extensional regime related to the post-collisional setting following the closure of Paleo-Tethys Ocean. Biotite ⁴⁰Ar-³⁹Ar isotopic analysis yields the plateau ages of (6.018±0.072)Ma and (5.675±0.059)Ma, respectively, which are considered as uplifting and cooling ages of the pluton, indicating that West Kunlun area undergoes a cooling-uplift event in Late Miocene. The event vehemently changes the tectonics, topography and geomorphology of West Kunlun and its adjacent area, gives rise to a regional arid climate, and impels the formation of Taklimakan Desert in Tarim Basin.