阿尔金南缘断裂东段晚第四纪活动特征

Activity Features of the East Segment of the South Altun Tagh Fault in Late Quaternary

阿尔金断裂的几何学和运动学特征对研究青藏高原构造演化和陆内地震机理非常重要。为定量科学研究较为薄弱的阿尔金南缘断裂东段的运动学参数,我们采用航卫片的解译、野外调查、地形测绘和年代学样品测试等多种方法对该段进行了初步研究。结果显示该段断裂主要以左旋走滑运动为主,且沿线存在较多的小位移,其位移空间分布的3个明显峰值分别为4.5m、8m和13m。根据河流阶地的左旋位移和相应的地貌面沉积年龄,得到晚第四纪以来阿尔金断裂东段的走滑速率约为2.7±0.9mm/a。基于所获得的定量参数,认为该段断裂向东以应变分解的形式将其应变量传递到相邻的逆冲断裂上。

Geometry and kinematics of the Altun Tagh fault play the important role in understanding of the Qinghai-Tibetan Plateau＇s tectonic revolution and continental earthquake mechanics. In order to determine kinematic parameters of the east segment of the south Altun Tagh fault, we applyseveral methods such as aerial photos and satellite imageries interpretation, field mapping, topographic measurement to study this fault preliminarily. The results show that the fault is with left-lateral slip movement, and many small displacements are reserved along the fault. There are three offset peaks： 4.5m, 8m, and 13m respectively. We calculated slip rate of about 2.7±0.9mm/a, with offset of river＇s terrace and depositional age of terrace. Based on these parameters, we conclude that strain partition occurred from the east segment to adjacentthrusts, and seismic risk of this section is relatively low in the future.