青藏高原东部及邻区地块现今运动特征

Present-day motion characteristics of blocks in the east of the Qinghai-Tibet plateau and adjacent areas

青藏高原东部及邻区为典型的大陆地壳变形区。根据GPS监测结果,得出了欧亚参考框架的运动速度场;采用刚性假设下最小二乘法,对地块现今运动进行了研究。GPS监测结果表明:柴达木地块、甘青地块、华南地块、川滇地块、印支地块运动速率分别为(11.95±2.89)mm/a,(11.86±2.32)mm/a,(7.83±2.08)mm/a,(13.18±2.43)mm/a,(6.45±1.95)mm/a;运动方向分别为61.1°,93.8,°113.1,°134.8,°141.6°;旋转速率分别为2.91×10-9rad/a,6.91×10-9rad/a,0.38×10-9rad/a,2.15×10-9rad/a,1.45×10-9rad/a。柴达木地块、甘青地块、川滇地块活动性较强,而华南地块、印支地块活动性较弱,属于稳定地块;各块体围绕东喜马拉雅构造结呈顺时针旋转。地块规律性运动特征与印度板块向北俯冲、推挤有作密切关系;而地块的差异运动则与总体构造应力条件下远程边缘效应及地块之间相互作用有关。

The east of the Qinghai-Tibet plateau and adjacent areas are the most typical mainland lithosphere distortion zones. According to GPS measurement, the velocity field on the Eurasia reference framework was obtained. And the velocity vector about the block motion and rotation was computed by least squares fitting under the hypotheses of rigid mass. GPS measurement shows that the movement velocities of the Qaidam block, Ganqing（Gansu-Qinghai） block, Huanan（South China） block, Chuandian （Sichuan-Yunnan） block, and Indian-China block, are （11.95±2.89）mm/a.（11.86±2.32）mm/a,（7.83±2.08）mm/a,（13.18±2.43）mm/a,（6.45±1.95）mm/a, respectively, the movement directions are 61.1°,93.8°,113.1°,134.8°,141.6°; respectively, and the rotation velocities are 2.91×10^-9 rad/a.6.91×10^-9 rad/a,0.38×10^-9 rad/a,2.15×10^-9 rad/a,1.45×10^-9 rad/a. respectively. The activity of the Qaidam block, Ganqing block and Chuandian block is stronger than that of the stable South China block and Indian-China block. Every block rotates clockwise around the east of the Himalayan syntaxis. The regulation motion characteristic of blocks is closely related to the collision and push of the India plate toward north, and differential motion of the blocks results from the reflection of fringe effect under the tectonics stress condition and interaction of the blocks.