U-Pb Isotope Geochronology of Syntectonic Granites from Hainan Island,South China:Constraints on Tectonic Evolution of the Eastern Paleo-Tethys Ocean  

作　　者：ZHOU Yang YAN Yi LIU Hailing CAI Jianxin ZHOU Mengfei ZHANG Xinchang WANG Yin SHEN Baoyun 

机构地区：[1]Key Laboratory of Ocean and Marginal Sea Geology,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China [4]Institute of Porous Flow and Fluid Mechanics,Chinese Academy of Sciences,Langfang 065007,China [5]SKL,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [6]School of Electromechanical Engineering,Guangdong University of Technology,Guangzhou 510006,China

出　　处：《Journal of Ocean University of China》2020年第6期1315-1330,共16页中国海洋大学学报（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Nos.41676048,U1701641,41776072,and 91328205);the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML 2019ZD0205);the Innovation Academy of South China Sea Ecology and Environmental Engineering(No.ISEE 2020YB07).

摘　　要：Since the recognition of the Indosinian orogeny in northern Vietnam,Triassic orogens have been widely identified around the western and southwestern boundaries of the South China block.The paleo-Tethys sutures stretch from west to southeast,from Jinshajiang-Ailaoshan via NE Vietnam to Hainan Island;these sutures exhibit and develop voluminous Permian-early Triassic magmatism and numerous high-strain shear zones.As ophiolites related to the paleo-Tethys are lacking on Hainan Island,the eastward extension of the Indosinian orogeny and subduction and closure time of the paleo-Tethys Ocean on Hainan Island remain controversial.Here,an integrated kinematic and geochronological study has been conducted on two shear zones,called the Xiaomei and Mangsan shear zones.U-Pb zircon dating yields an age of early Triassic(252-251 Myr)for Xiaomei syntectonic granites which formed in the same tectonic setting and presented the similar nanoparticles to the Indosinian granites from Ailaoshan ductile shear zone,including the strawberry-like and flower-like nanoparticles.The NE-trending Mangsan shear zone represented by the gneissic granites with middle Permian ages(264-262 Myr)formed in the same tectonic setting as the Wuzhi-shan granites that were proposed as I-type granites.These middle Permian gneissic granites with arc affinity may represent an arc setting related to the NW subduction of the paleo-Tethys.The analyses reveal that granites with late Triassic ages(235-232 Myr)in the Xiaomei shear zone have the characteristics of A-type granites.The late Triassic extensional events on Hainan Island may be related to the subduction of the paleo-Pacific Plate beneath the East Asian continent.

关 键 词：Indosinian orogeny Hainan Island Xiaomei shear zone Mangsan shear zone syntectonic granites PALEO-TETHYS 

分 类 号：P736.22[天文地球—海洋地质] P597.3[天文地球—海洋科学]