南海新生代沉积基底性质和盆地类型

The Basement Features and Basin Types of Cenozoic Sediments in South China Sea

根据新的重磁、地震及钻井资料,结合大地构造性质和新生代主要构造变形特征,将南海新生代沉积盆地基底划分为三个基底区,即北部古生界断陷基底区、西部中—古生界走滑拉分基底区以及南部复杂基底区。北部基底区以古生界变质基底为主,同时含有中生界残留断陷,它由北部湾断陷基底区、珠江口中—古生界断陷基底区以及西沙古生界断陷基底区三个次级区构成;西部基底区以走滑伸展为特征,分为莺歌海古生界、中建南中生界以及万安中生界等三个次级走滑拉分基底区;南部基底区较复杂,划分为曾母新生代早期褶皱基底区和南沙中—古生界复杂基底区。这八个次级基底区之间主要以俯冲—碰撞缝合带、蛇绿岩带、深海放射虫沉积岩带、洋中脊火成岩带以及深大走滑转换断裂带等分隔,各自有着不同的演化历史,控制了南海新生代多种类型次级沉积盆地的地质特征。

Based on gravity anomalies, magnetic signatures, seismic dara, drilled wells, and geotectonic property and Cenozoic major tectonic deformation, three basement areas of the Cenozoic basin, i.e. the northern, the western and the southern ones, can be divided in South China Sea. The northern basement is characterized by Paleozoic meta- morphic rock and Mesozoic residual faulted depression and it is be further divided into 3 subareas, which include the Beibu Gulf basement subarea, the Pearl River Mouth Paleozoic basement subarea and the Xisha Islands Paleozoic basement subarea. The western one is characterized by strike-slips and it includes 3 sub-zones, i.e. the Yinggehai Paleozoic basement subarea, the Zhongjiannan and the Wanan Mesozoic basement subareas. The southern one is more complex and it is divided to 2 sub-areas,i.e, the Zengmu early Cenozoic folded basement subarea and the Nansha Paleozoic-Mesozoic complex basement subarea. These 8 sub-areas are separated each other from the subduction-collision suture belt, the ophiolite suite belt, the deep-sea radiolarite belt, the mid-ocean ridge basalt belt and the deep great strike-slip fracturing belt. These belts show different evolution histories and dominate several types of geological characteristics of Cenozoic sub-basins in South China Sea.