青藏高原东部主要活动地块运动演化特征分析

Analysis of evolution characteristics of main active blocks in eastern Tibetan Plateau

针对活动地块相对运动随时间的演化,该文利用多期GPS速度场资料,基于刚性运动模型分析了青藏高原东部多个活动地块的运动演化特征。首先为保证多期速度场的可比性,采用拟准检定(QUAD)优选算法将多期速度场转换到统一的稳定华南基准;然后基于刚性块体模型计算了多个活动地块相对华南地块的运动演化特征,结果显示柴达木、祁连、阿拉善和鄂尔多斯的运动速率明显小于巴颜喀拉、羌塘、川西北和滇中地块,且自羌塘向北东方向的巴颜喀拉再至南部的川西北和滇中地块表现为绕喜马拉雅东构造结的顺时针旋转运动。多期结果表明,除阿拉善和鄂尔多斯地块外,其余活动地块在汶川地震前后均出现显著的调整过程,说明汶川地震对周边活动地块整体运动的影响显著。

Aiming at the evolution of relative motion of active blocks over time,this paper analyzed the motion evolution characteristics of several active blocks in the eastern Tibetan Plateau based on the rigid movement model using multi-period global positioning system（GPS）velocity field data.First GPS velocity field in 3 periods relative to Huanan block was obtained based on quasi-accurate detection of gross errors（QUAD）methods which could establish an unified stable reference frame.Then the relative movements of active blocks were calculated based on the rigid model of blocks.The results showed that active blocks in the northern segments of north south seismic zone behaved in relatively small rates than those in the southern segments.What＇s more the blocks nearby behaved similarly to each other such as Chuanxibei and Dianzhong blocks which expressed as a clockwise rotation around the Himalayan east tectonic knot.Otherwise blocks in the northern segment were little affected by Wenchuan earthquake,especial Alashan and Erdos blocks.