An Overview on the Composition and Age of Upper Crust of Proto-Tethyan Lajishan Intra-oceanic Arc,NE Tibet PlateauOACSTPCD
An Overview on the Composition and Age of Upper Crust of Proto-Tethyan Lajishan Intra-oceanic Arc,NE Tibet Plateau
Identification and anatomy of oceanic arcs within ancient orogenic belt are significant for better understanding the tectonic framework and closure process of paleo-ocean basin.This article summarizes the geological,geochemical,and geochronological characteristics of upper crust of Proto-Tethyan Lajishan intra-oceanic arc and provides new data to constrain the subduction evolution of the South Qilian Ocean.The intra-oceanic arc volcanic rocks,including intermediate-mafic lava,breccia,tuff,and minor felsic rocks,are distributed along southern part of the Lajishan ophiolite belt.Geochemical and isotopic compositions indicate that the intermediate-mafic lava were originated from depleted mantle contaminated by sediment melts or hydrous fluids,whereas the felsic rocks were likely generated by partial melting of juvenile mafic crust in intra-oceanic arc setting.Zircons from felsic rocks yield consistent and concordant ages ranging from 506 to 523 Ma,suggesting these volcanic rocks represent the relicts of upper crust of the Cambrian intra-oceanic arc.Combined with the Cambrian forearc ophiolite and accretionary complex,we suggest that the Cambrian intra-oceanic arc in the Lajishan ophiolite belt is belonging to the intra-oceanic arc system which was generated by south-directed subduction in the South Qilian Ocean at a relatively short interval between approximately 530 and 480 Ma.
FU Changlei;HE Xiaohu;YAN Zhen;Jonathan C.AITCHISON;XIAO Wenjiao;WANG Bingzhang;LI Wufu;LI Yusen
SinoProbe Laboratory,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China||Key Laboratory of the Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources,Qinghai Geological Survey Institute,Xining 810012,ChinaDepartment of Geology,School of Earth Sciences,Yunnan University,Kunming 650091,ChinaSinoProbe Laboratory,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,ChinaSchool of Earth and Environmental Sciences,University of Queensland,Brisbane 4072,AustraliaXinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China||State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,ChinaKey Laboratory of the Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources,Qinghai Geological Survey Institute,Xining 810012,ChinaSinoProbe Laboratory,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China||School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China
volcanic rocksintra-oceanic arcU-Pb ageLajishan ophiolite beltSouth Qilian OceanProto-Tethyan realm
《地质学报（英文版）》 2024 (002)
285-302 / 18
We greatly appreciate the constructive comments from editors and reviewers.This work was supported by the China Geological Survey(Grant No.DD20221649),National Natural Science Foundation of China(Grant Nos.42230308,42072266),Bureau of Geological Exploration and Development of Qinghai Province(Grant No.[2022]32),the Xingdian Scholar Fund of Yunnan Province(Grant No.C6213001155),China Postdoctoral Science Foundation(Grant No.2021M691702),and High-level Talents Project of Qinghai Province.
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