An Overview on the Composition and Age of Upper Crust of Proto-Tethyan Lajishan Intra-oceanic Arc,NE Tibet Plateau

FU Changlei ¹HE Xiaohu ²YAN Zhen ³Jonathan C.AITCHISON ⁴XIAO Wenjiao ⁵WANG Bingzhang ⁶LI Wufu ⁶LI Yusen⁷

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作者信息

1. 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,China
2. Department of Geology,School of Earth Sciences,Yunnan University,Kunming 650091,China
3. SinoProbe Laboratory,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China
4. School of Earth and Environmental Sciences,University of Queensland,Brisbane 4072,Australia
5. Xinjiang 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,China
6. Key Laboratory of the Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources,Qinghai Geological Survey Institute,Xining 810012,China
7. SinoProbe 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
折叠

Abstract

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.

Key words

volcanic rocks/intra-oceanic arc/U-Pb age/Lajishan ophiolite belt/South Qilian Ocean/Proto-Tethyan realm

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基金项目

constructive comments from editors and reviewers()

China Geological Survey(DD20221649)

National Natural Science Foundation of China(42230308)

National Natural Science Foundation of China(42072266)

Bureau of Geological Exploration and Development of Qinghai Province([2022]32)

Xingdian Scholar Fund of Yunnan Province(C6213001155)

China Postdoctoral Science Foundation(2021M691702)

Highlevel Talents Project of Qinghai Province()

出版年

2024

地质学报(英文版)

中国地质学会

地质学报(英文版)

CSTPCD

影响因子：1.414

ISSN：1000-9515

参考文献量91

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