Petrogenesis and tectonic implications of the Silurian adakitic granitoids in the eastern segment of the Qilian Orogenic Belt,Northwest China  

作　　者：Jiao-Long Zhao Xiao-Jun Huang Pei-Qing Hu Zhen-Xi Yang Ying Fan Er-Teng Wang Fu-Bo Yang Jing-Yu Zhang 

机构地区：[1]School of Earth Sciences,Key Laboratory of Mineral Resources in Western China(Gansu Province),Lanzhou University,Lanzhou 730000,China [2]Nuclear Industry 247 Brigade,Tianjin North China Geological Survey Bureau,Tianjin 301800,China [3]Fourth Institute of Geological and Mineral Exploration of Gansu Provincial Bureau of Geology and Mineral Resources,Jiuquan 735000,China

出　　处：《Acta Geochimica》2024年第1期72-86,共15页地球化学学报（英文）

基　　金：funded by Gansu Provincial Natural Science Foundation (Grant Numbers 21JR7RA503 and22JR5RA819);the Fundamental Research Funds for the Central Universities (Grant lzujbky-2021-ct07);the Key Talent Project of Gansu Province (2022-Yangzhenxi);the National Second Expedition to the Tibetan Plateau (2019QZKK0704)。

摘　　要：Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and systematic whole-rock geochemical data for the Haoquangou and Liujiaxia granitoids within the North Qilian orogenic belt and the Qilian Block, respectively, to constrain their petrogenesis, and the Silurian tectonic evolution of the Qilian orogenic belt. Zircon U–Pb ages indicate that the Haoquangou and Liujiaxia intrusions were emplaced at423 ± 3 Ma and 432 ± 4 Ma, respectively. The Haoquangou granodiorites are calc-alkaline, while the Liujiaxia granites belong to the high-K calc-alkaline series.Both are peraluminous in composition and have relatively depleted Nd isotopic [ε_(Nd)(t) =(-3.9 – + 0.6)] characteristics compared with regional basement rocks, implying their derivation from a juvenile lower crust. They show adakitic geochemical characteristics and were generated by partial melting of thickened lower continental crust. Postcollisional extensional regime related to lithospheric delamination was the most likely geodynamic mechanism for the generation of the Haoquangou granodiorite, while the Liujiaxia granites were generated in a compressive setting during continental collision between the Qaidam and Qilian blocks.

关 键 词：Silurian adakitic granitoids PETROGENESIS Tectonic setting Qilian Orogenic Belt 

分 类 号：P534.43[天文地球—古生物学与地层学] P588.121[天文地球—地质学]