Modern activity in the southern and central parts of the Xiaojiang fault in Yunnan
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摘要: 小江断裂为川滇地块、华南地块的边界断裂,是一条重要活动断裂。本文利用GPS监测结果,综合处理得到了欧亚框架下的运动速度场,并以此为基础,采用刚性假设下最小二乘法,对小江断裂中南各段的运动速度进行计算。计算结果表明:断裂中段东支断裂运动速度为3.37±3.20mm/a,西支断裂为3.29±2.73mm/a;断裂南段为3.63±1.76mm/a。整个断裂表现为左行走滑为主兼有挤压活动的特征。这一结果与大的构造环境一致,表明在印度板块与青藏高原的挤压碰撞下,高原东部川滇地块受华南地块、印支地块的阻挡作用,小江断裂产生逆时针移动,呈左行走滑特征。Abstract: 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.
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Keywords:
- Xiaojiang fault /
- GPS /
- velocity /
- Yunnan
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