Geodynamic processes of the southeastern Neo-Tethys Ocean and the formation mechanism of the curved subduction system in Southeast Asia  

作　　者：Weiwei DING Rixiang ZHU Bo WAN Liang ZHAO Xiongwei NIU Pan ZHAO Baolu SUN Yanghui ZHAO 

机构地区：[1]Key Laboratory of Submarine Geoscience&Second Institute of Oceanography,Ministry of Natural Resrouce,Hangzhou 310012,China [2]State Key Laboratory of Lithosphere Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Science China Earth Sciences》2023年第4期703-717,共15页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.42025601,41890811&92155203)。

摘　　要：Southeast Asia is located at the intersection of the Tethys and Pacific domains. The superimposed effects of the two tectonic domains have resulted in complicated deep structure, surface magma responses, and dynamic processes of Southeast Asia. Based on the latest long-term passive seismic experiment and numerical modeling, this study reconstructs the dynamic processes of the closure of the Neo-Tethys Ocean and the formation of the curved subduction system in Southeast Asia since the Late Mesozoic. P-wave velocity structure shows a remnant of the Neo-Tethys subducted slab in the lower mantle beneath Southeast Asia at a depth of approximately 1500 km. On the Java-East Timor subduction zone, the remnant slab is coupled with the Indo-Australian subducting slab in the upper mantle with the same direction, while on the Sumatra subduction zone, the remnant slab is decoupled from the Indo-Australian subducting slab in different directions. The formation of the curved subduction system in Southeast Asia is resulted from the northward subdcutions of previous Neo-Tethys and current IndoAustralian Plate, and the westward subduction of the Pacific Plate since Mesozoic. The former is characterized by continuous subduction and subsequent continental block collision, forming the current continental lithosphere in Southeast Asia and the curve-shaped Sumatra-Java subduction zone;the latter is characterized by subduction retreat and back-arc spreading, forming the eastern Philippine subduction zone and a series of marginal sea basins. Since the Early Cretaceous, the opening of the North Australian Sea resulted in stagnation of the Australian Block in the high latitude area of the southern hemisphere for a long time.The North Australian Sea was dominated by out-dipping double subduction from 45 Ma, which resulted in rapid northward drifting of the Australian Block and final collision with the Sundaland.

关 键 词：Southeastern Neo-Tethys Ocean Curved subduction system in Southeast Asia North Australian Sea Deep structure Numerical modeling 

分 类 号：P542[天文地球—构造地质学]