南海构造变形分区及成盆过程

Tectonic Province Divisions in the South China Sea:Implications for Basin Geodynamics

为了系统认识新生代南海沉积盆地形成演化过程和成盆机制,在对南海及其周缘区域构造和沉积研究进展调研的基础上,利用覆盖南海主要盆地新近采集和重处理的地震剖面开展详细的构造-地层分析.基于盆地结构构造、演化特征和成盆动力学的差异性,以红河-越东-Lupar线大型走滑构造带为界,将南海及其周缘沉积盆地划分为古南海俯冲拖拽构造区沉积盆地群和挤出-逃逸构造区沉积盆地群,前者主要是古南海俯冲及其所引起的区域构造变形形成的盆地,包括北部湾、琼东南、珠江口、曾母、北康、文莱-沙巴和礼乐等盆地,后者是印度-欧亚大陆碰撞导致印支地块挤出和旋转形成的盆地,如莺歌海、湄公、中建南、万安等盆地.最后,结合周缘板块动力学事件和本次对盆地构造研究的成果,特别是盆地中重要界面属性的重新厘定,建立了南海及其周缘沉积盆地演化过程.

In order to better understand the evolution and mechanism of Cenozoic sedimentary basins in the South China Sea, we employed tectono-stratigraphic analysis on the sedimentary basins in the South China Sea. Reviewing the previous studies on the tectonics and sedimentation in the South China Sea and its peripheral regions, we used a compilation of newly acquisition and reprocessed seismic reflection profiles covering the large basins and got a clear result of the basins in the South China Sea with different basin structures, evolutions and mechanism. Considering the nature of the basin developed in the South China Sea, we suggested in our paper that the basins in the South China Sea can be divided into two sedimentary basin groups by a tectonic boundary, which is characterized by a transform boundary of the Red River fault extended south along the Vietnamese margin and joined with the trench along the Lupar line. These two basin groups are eollsion-extrusion tectonic province basin group and Proto-south China Sea slab pull tectonic province basin group. The Proto-South China Sea tectonic province basin group is strongly controlled by the southward subduction of Proto-South China Sea. These basins include Beibuwan, Qiongdongnan, Pearl River Mouth, Zengmu, Beikang, Brunei-Sabah, Liyue basins and so on.However, the evolution of the collision-extrusion tectonic province basin group is controlled by the extrusion toward the southeast and rotation of Indochina block, which is as a result of the indentation of rigid India into Asia. This kind of basins mainly includes Yinggehai, Zhongjiannan, Mekong, Wan＇an basins and so on. Considering the peripheral plate dynamic events, the tectonics of these basins and significant bounda- ries refined on the seismic profiles, the evolution of the South China Sea and its peripheral regions is reconstructed in our paper.