A-type granites induced by a breaking-off and delamination of the subducted Junggar oceanic plate,West Junggar,Northwest China  

作　　者：Chu Wu Tao Hong Xing-Wang Xu Cheng-Xi Wang Lian-Hui Dong 

机构地区：[1]Development and Research Center of China Geological Survey,Ministry of Natural Resources,Beijing 100037,China [2]Guangdong Provincial Key Lab of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,China [3]Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,China [4]Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [5]University of Chinese Academy of Sciences,Beijing 100049,China [6]Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China [7]Xinjiang Bureau of Geology and Mineral Resources,Urumqi,Xinjiang 830000,China

出　　处：《China Geology》2022年第3期457-474,共18页中国地质（英文）

基　　金：jointly supported by the National Natural Science Foundation of China (41802093);the National Key Research and Development Program of China (2017YFC0601201 and 2018YFC0604002);the Project of Xinjiang Bureau of Geology and Mineral Resources (2011BAB06B03-3);the Project of China Geological Survey (DD20190405 and DD20190406);the Fundamental Research Funds for the Central Universities, Sun Yat-sen University (2021qntd23).

摘　　要：The A-type granites with highly positiveε_(Nd)(t)values in the West Junggar,Central Asian Orogenic Belt(CAOB),have long been perceived as a group formed under the same tectonic and geodynamic setting,magmatic sourceq and petrogenetic model.Geological evidence shows that these granites occurred at two different tectonic units related to the southeastern subduction of Junggar oceanic plate:the Hongshan and Karamay granites emplaced in the southeast of West Junggar in the Baogutu continental arc;whereas the Akebasitao and Miaoergou granites formed in the accretionary prism.Here the authors present new bulk-rock geochemistry and Sr-Nd isotopes,zircon U-Pb ages and Hf-O isotopes data on these granites.The granites in the Baogutu continental arc and accretionary prism contain similar zirconε_(Hf)(t)values(+10.9 to+16.2)and bulk-rock geochemical characteristics(high SiO_(2)and K_(2)O contents,enriched LILEs(except Sr),depleted Sr,Ta and Ti,and negative anomalies in Ce and Eu).The Hongshan and Karamay granites in the Baogutu continental arc have older zircon U-Pb ages(315-305 Ma)and moderate^(18)O enrichments(δ^(18)_(O_(zircon))=+6.41‰-+7.96‰);whereas the Akebasitao and Miaoergou granites in the accretionary prism have younger zircon U-Pb ages(305-301 Ma)with higher^(18)O enrichments(δ^(18)_(O_(zircon))=+8.72‰-+9.89‰).The authors deduce that the elevated^(18)O enrichments of the Akebasitao and Miaoergou granites were probably inherited from low-temperature altered oceanic crusts.The Akebasitao and Miaoergou granites were originated from partial melting of low-temperature altered oceanic crusts with juvenile oceanic sediments below the accretionary prism.The Hongshan and Karamay granites were mainly derived from partial melting of basaltic juvenile lower crust with mixtures of potentially chemical weathered ancient crustal residues and mantle basaltic melt(induced by hot intruding mantle basaltic magma at the bottom of the Baogutu continental arc).On the other hand,the Miaoergou charnockite might be sourced fr

关 键 词：A-type granite plutons Sr-Nd-Hf-O isotopes Breaking-off and delamination Subducted Junggar oceanic plate West Junggar Central Asian Orogenic Belt 

分 类 号：P588.121[天文地球—岩石学]