Geochemistry and Tectonic History of Seamount Remnants in the Xingshuwa Subduction Accretionary Complex of the Xar Moron Area,Eastern Margin of the Central Asian Orogenic Belt  

作　　者：CHENG Yang XIAO Qinghui LI Tingdong LI Yan FAN Yuxu XU Liquan GUO Lingjun PANG Jinli 

机构地区：[1]Institute of Mineral Resources Research,China Metallurgical Geology,Bureau,Beijing 101300,China [2]Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [3]General Prospecting Institute,China National Administration of Coal Geology,Beijing 100039,China [4]Inner Mongolia Key Laboratory of Magmatic Mineralization and Ore-Prospecting,Hohhot 010020,China

出　　处：《Acta Geologica Sinica(English Edition)》2021年第4期1086-1098,共13页地质学报（英文版）

基　　金：financially supported by the Inner Mongolia Autonomous Region Geological and Mineral Exploration Fund(Grant Nos.2017-YS01,2020-YS01)。

摘　　要：This study focuses on the geology,geochemistry,zircon U-Pb geochronology and tectonic settings of the three types of seamount basalts from the Xingshuwa subduction accretionary complex in the Xar Moron area,eastern margin of the Central Asian Orogenic Belt(CAOB).The seamount remnants are composed of carbonate’cap’sediments,large volumes of pillow and massive basalts,carbonate breccia slope facies and radiolarian cherts.Group 1 basalts are characterized by high contents of P2 O5 and TiO2 with alkaline affinity and LREE enrichment,indicating that they are derived from intraplate magma.Group 2 basalts display N-MORB LREE depletion patterns,indicating that they were formed at a mid-ocean ridge.Group 3 basalts have shown distinct Nb depletion and high Th/Yb ratios,indicating that they were generated in an island arc tectonic setting.The zircon U-Pb age of Group 1 basalt sample XWT18-131 is 576.4±9.4 Ma,suggesting that the oceanic island seamount was the product of intraplate magmatism related to a mantle plume or’hot spot’in the late Neoproterozoic.The zircon U-Pb age of Group 2 basalt sample XWT18-132 is 483±22 Ma,indicating that the Paleo-Asian Ocean(PAO)was continuously expanding in the Early Ordovician.The zircon U-Pb age of Group 3 basalt sample XWT18-101 is 240.5±8.2 Ma,suggesting that this area underwent the evolutionary path of ocean-continent transition,developing towards continentalization during the Middle Triassic.Thus,we believe that there was both mantle plume-related intraplate magmatism and intraoceanic subduction during the evolution of the PAO,the CAOB possibly being an evolutionary model of an intraoceanic subduction and mantle plume magmatism complex.

关 键 词：SEAMOUNT GEOCHEMISTRY U-Pb geochronology of zircons tectonic setting Paleo-Asian Ocean 

分 类 号：P587[天文地球—岩石学] P597.3[天文地球—地质学]