Geochronology,geochemistry,and Sr-Nd isotopes of Early Carboniferous magmatism in southern West Junggar,northwestern China: Implications for Junggar oceanic plate subduction

LIU Pengde ¹LIU Xijun ²XIAO Wenjiao ³ZHANG Zhiguo ¹SONG Yujia ¹XIAO Yao ¹LIU Lei ²HU Rongguo ¹WANG Baohua⁴

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作者信息

1. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,College of Earth Sciences,Guilin University of Technology,Guilin 541004,China
2. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,College of Earth Sciences,Guilin University of Technology,Guilin 541004,China;Xinjiang Research Center for Mineral Resources,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China;Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resource,Guilin University of Technology,Guilin 541004,China
3. Xinjiang Research Center for Mineral Resources,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China
4. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,College of Earth Sciences,Guilin University of Technology,Guilin 541004,China;Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resource,Guilin University of Technology,Guilin 541004,China
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Abstract

West Junggar is a key area for understanding intra-oceanic plate subduction and the final closure of the Junggar Ocean. Knowledge of the Carboniferous tectonic evolution of the Junggar Ocean region is required for understanding the tectonic framework and accretionary processes in West Junggar, Central Asian Orogenic Belt. A series of Early Carboniferous volcanic and intrusive rocks, namely, basaltic andesite, andesite, dacite, and diorite, occur in the Mayile area of southern West Junggar, northwestern China. Our new LA-ICPMS zircon U-Pb geochronological data reveal that diorite intruded at 334 (±1) Ma, and that basaltic andesite was erupted at 334 (±4) Ma. These intrusive and volcanic rocks are calc-alkaline, display moderate MgO (1.62％-4.18％) contents and Mg# values (40-59), and low Cr (14.5×10-6-47.2×10-6) and Ni (7.5×10-6-34.6×10-6) contents, and are characterized by enrichment in light rare-earth elements and large-ion lithophile elements and depletion in heavy rare-earth elements and high-field-strength elements, meaning that they belong to typical subduction-zone island-arc magma. The samples show low initial 87Sr/86Sr ratios (range of 0.703649-0.705008), positive εNd(t) values (range of 4.8-6.2 and mean of 5.4), and young TDM Nd model ages ranging from 1016 to 616 Ma, indicating a magmatic origin from depleted mantle involving partial melting of 10％-25％ garnet and spinel lherzolite. Combining our results with those of previous studies, we suggest that these rocks were formed as a result of northwestward subduction of the Junggar oceanic plate, which caused partial melting of sub-arc mantle. We conclude that intra-oceanic arc magmatism was extensive in West Junggar during the Early Carboniferous.

Key words

Early Carboniferous magmatism/geochronology/geochemistry/Junggar Oceanic plate subdution/West Junggar/Central Asian Orogenic Belt

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基金项目

This study was jointly supported by the CAS"Light of West China"Program(2018-XBYJRC-003)

National Natural Science Foundation of China(41772059)

National Natural Science Foundation of China(92055208)

Guangxi Natural Science Foundation for Distinguished Young Scholars,China(2018GXNSFFA281009)

and the Fifth Bagui Scholar Innovation Project of Guangxi Zhuang Autonomous Region,China()

出版年

2021

干旱区科学

中国科学院新疆生态与地理研究所,科学出版社

干旱区科学

CSTPCDCSCDSCI

影响因子：1.743

ISSN：1674-6767

被引量2

参考文献量5

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