维西—乔后断裂北段晚第四纪活动的地质地貌表现

Geological and Geomorphological Features of Late Quaternary Activity in the Northern Segment of Weixi-Qiaohou Fault

维西—乔后断裂位于青藏高原与云贵高原接壤地带,是青藏高原东南缘一条规模较大的活动断裂。研究其新构造活动特征对认识川滇块体构造格局和运动图像具有重要的科学意义。据野外详细的地质地貌调查结果,重点阐述断裂北段的运动特征及其滑动速率。研究表明:白济讯、维西县城及扎你洛等地均发现晚更新世活动的地质证据,有明显的晚第四纪活动迹象;该段运动性质以右旋走滑为主,根据阶地扭曲、陡坎等测得其水平滑动速率为1.0~1.2 mm/a,垂直滑动速率为0.3~0.4 mm/a。

The Weixi–Qiaohou fault located at the borders zone of the Tibetan and Yunnan–Guizhou plateaus is a large-scale active fault on the southeast margin of the Tibetan Plateau.Studying its neotectonic activity has considerable scientific importance for understanding the tectonic framework and movement of the Chuan–Dian block.In this study,the movement and sliding rate of the northern segment of the fault are described mainly based on the results of detailed field geological and geomorphic investigations.The research results have provided geological evidence of Late Pleistocene activity at Baijixun,Weixi County,and Zhaniluo,which is highly indicative of Late Quaternary activity.This segment movement is mainly dominated by dextral slip,with a horizontal slip rate of 1.0–1.2 mm/a and a vertical slip rate of 0.3–0.4 mm/a according to the terrace distortion and scarps.