用双三次样条函数和GPS资料反演现今中国大陆构造形变场

CONTEMPORARY HORIZONTAL TECTONIC DEFORMATION FIELDS IN CHINA INVERSED FROM GPS OBSERVATIONS

将中国大陆现今构造变动视为一种连续的地壳变形 ,利用双三次样条函数模拟了近期 GPS测定的大陆内部及周边地区 4 12个测站速率 ,反演大陆地区自洽的构造变动速度场和应变率场。模拟结果显示 :印度板块与欧亚板块的碰撞、挤压是构成中国大陆内部岩石层水平形变的主要驱动力。印度板块在东喜马拉雅构造结深深插入青藏高原 ,造成地壳大规模的缩短和抬升。青藏高原东南部的喜马拉雅带、拉萨和羌塘地块以及青藏高原东南边的川滇地区 ,内部构造活动强烈 ,其内部的构造变形包含地壳碎片的冲断、褶皱和侧向逃逸。大陆地壳 (或岩石圈 )的增厚 ,尤其是喜马拉雅山脉南北向的快速缩短和青藏高原东西向的缓慢拉张 ,大约吸收了印欧板块会聚量的 85 % ,西藏中东地区东西向的拉张速率达到了 (16± 2 .0 ) mm/ a,且顺时针方向扭转明显。印度板块相对欧亚板块运动的欧拉极为 (2 9.7°N,19.3°E,0 .392°/ Ma) ;华南地块相对于欧亚大陆向东 (10 2°± 7.4°)南的运动速率是 (11± 1.5 4 )mm/ a,华南块体相对欧亚板块运动的欧拉极为 (6 2 .2 5°N,12 6 .5 6°E,0 .14 1°/ Ma) ;塔里木地块相对较稳定 ,其西部运动速度高于东部运动速度 ,作顺时针方向旋转。总体上讲 ,中国大陆运动方向为北偏东呈辐射状 ,从西部近南北方向的?

Assuming that the contemporary tectonic activity in China can be treated as continuous. We have simulated 412 present day multiple epoch Global Positioning System (GPS) velocity solution in China with a bi cubic spline interpolation function to inverse the self consistent horizontal velocity and strain rate fields in China.The modelling results show that the collision of the India Plate with the Eurasia Plate is the main driving force causing crustal horizontal deformation of China. The shortening and uplift on a large scale is due to the deep underthrusting of India into beneath the Tibet at Eastern Himalayan Syntaxis.In the modelling velocity field,about 85 percent of India's convergence with Eurasia is absorbed by crust, or lithosphere thickening,especially the quick north south shortening along Himalaya and the slow E W extension within the Qing Zang Plateau.In the east central Tibet,the E W extension rate is up to (16±2.0) mm/a and torsion clockwise is in evidence.India moves relatively to Eurasia about a pole of rotation at (29.7°N, 19.3°E 0.392°/Ma),south China block moves at(11±1.54)mm/a in the direction of (102°±7.4°) with the pole position(62.25°N,126°E,0.141°/Ma).The Tarim Basin is stable relatively,the velocity of west area to Tarim is higher than that of the east,rotates clockwise.In general,the movement direction of China continent is N E and in a radiation status.The N S compression rate across Himalaya and the Qing Zang Plateau is (19±2.0) mm/a (13±1.5)mm/a at western Tianshan tectonic belt and (6±1.4)mm/a at eastern Tianshan tectonic belt.The left lateral strike slip rate of the Altyn Fault is (6±1.2)mm/a.