Modern activity in the southern and central parts of the Xiaojiang fault in Yunnan

The Xiaojiang fault as the boundary fault is considered as an important active fault between the SichuanYunnan and South China blocks. The GPS velocities for the southern and central parts of the Xiaojiang fault are calculated by means of the method of least squares on the basis of GPS velocities in the Eurasian reference framework at 3.37 ±3.20 mm/a for the eastern branch and 3.29 ±2.73 mm/a for the western branch in the middle part of the fault, and 3.63 ±1.76 mm/a for the southern part of the fault. These data coincide with those from the tectonic settings of the study area. Influenced by the collision and compression of the Qinghai-Xizang Plateau and obstruction of the SichuanYunnan blocks by the South China and Indian blocks, a counterclockwise rotation of the Xiaojiang fault caused the leftla teral strike-slip faulting of the fault.