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 characteriz...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.展开更多
基金financially supported by the China Geological Survey(Nos.12120115069701,12120113095700 and 1212011220391)the National Natural Science Foundation of China(No.41272079)+2 种基金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)
文摘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.
