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
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+FeOT), 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.
East Kunlun granodiorite geochronology Hf isotope magmatism
Fuhao Xiong Changqian Ma Hongan Jiang Hang Zhang
Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation, Ministry of Land State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Changsha Uranium Geology Research Institute, CNNC, Changsha 410007, China
国际会议
武汉
英文
474-490
2015-10-16（万方平台首次上网日期，不代表论文的发表时间）