Geochronology and Petrogenesis of Triassic High-K Calc-Alkaline Granodiorites in the East Kunlun Orogen,West China:Juvenile Lower Crustal Melting during Post-Collisional Extension

作     者：Fuhao Xiong Changqian Ma Hong’an Jiang Hang Zhang 

作者机构：Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon AccumulationMinistry of Land and ResourcesCollege of Earth SciencesChengdu University of TechnologyChengdu 610059China State Key Laboratory of Continental Tectonics and DynamicsInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China State Key Laboratory of Geological Processes and Mineral ResourcesChina University ofGeosciencesWuhan 430074China Changsha Uranium Geology Research InstituteCNNCChangsha 410007China 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2016年第27卷第3期

页      面：474-490页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：financially supported by the China Geological Survey(Nos.12120115069701,12120113095700 and 1212011220391) the National Natural Science Foundation of China(No.41272079) the China Postdoctoral Science Foundation-China(No.2015M582529) the State Key Laborato-ry of Continental Tectonics and Dynamics(No.K201508) the Special Financial Support Program of Central Government for Local Universities(No.80000-14Z019) 

主　　题：East Kunlun granodiorite geochronology Hf isotope magmatism 

摘      要：This study reports zircon U-Pb and Hf isotopes and whole-rock elemental data for granodiorites from the East Kunlun orogen. The zircon U-Pb dating defines their crystallization age of 235 Ma. The rocks are characterized by high-K calc-alkaline, magnesian and metaluminous with（K2O＋Na2O）=6.38 wt.%–7.01 wt.%, Mg#=42–50 [Mg#=100×molar Mg/（Mg＋Fe OT）], A/CNK=0.92–0.98, coupled with high εHf（t） values from-0.65 to-1.80. The rocks were derived from partial melting of a juvenile mafic crustal source within normal crust thickness. The juvenile lower crust was generated by mixing lithospheric mantle-derived melt（55%–60%） and supracrustal melt（40%–45%） during the seafloor subduction. Together with available data from the East Kunlun, it is proposed that the studied Middle Triassic granodiorites were formed in post-collisional extension setting, in which melting of the juvenile lower crust in response to the basaltic magma underplating resulted in the production of high-K granodioritic melts.