南海深部地球动力学特征及其演化机制  

CHARACTERISTICS AND MECHANISM OF GEODYNAMIC EVOLUTION OF THE SOUTH CHINA SEA

作　　者：张健[1] 熊亮萍[2] 汪集旸[2] 

机构地区：[1]中国科学院研究生院地学部,北京100039 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2001年第5期602-610,共9页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目 (4 0 0 740 2 2 ;4973 2 0 0 5 );国家重点基础研究发展规划项目 (G2 0 0 0 0 467)联合资助

摘　　要：利用地热学、流变学和重力学方法 ,计算了南海岩石层温度结构、流变特征及地幔对流格局 .南海莫霍面温度在 6 0 0— 1 0 0 0℃之间 .岩石层底界面温度在 1 1 5 0— 1 3 0 0℃之间 ,有效粘滞系数为 1 0 2 0 — 1 0 2 1 Pa·s,与冰期回弹资料确定的地幔粘度吻合 ,表明南海深部具备产生地幔热对流的物理条件 .研究认为地幔物质由北西向南东方向的运移以及印澳 -欧亚板块的碰撞 ,导致南海北部大陆边缘向洋扩张、离散和断裂解体 .在向洋离散过程中 ,陆 -洋岩石层底部地幔局部对流使中央海盆扩张和北部陆缘发生差异性块断运动 .HTWTBased on the geothermal and gravitation methods, this paper investigated the rheological and thermal structure of the lithosphere under the south China sea and computed the convective mode of the mantle. The result shows that the Moho temperature is about 600-1000℃, and at the bottom of the lithosphere the temperature is about 1150-1300℃. The viscous coefficient of the upper mantle is 10 20 -10 21 Pa·s which corresponds to that determined by the rate of postglacial rebound. It is suggested that the physical condition is suitable for mantle convection under the lithosphere of the south China sea. Following the mantle convection and the collision between the Indo-Australia plate and the Eurasia plate, the northern continental margin outspreads toward ocean and the subbasin expands at the centre of the south China sea.

关 键 词：岩石层热结构 流变性 地幔对流 南海 演化机制 地球动力学 

分 类 号：P313[天文地球—固体地球物理学] P541[天文地球—地球物理学]