文山—麻栗坡断裂北段晚第四纪活动地质地貌证据与滑动速率研究

Geomorphologic Evidence of Late Quaternary Activity and Sliding Rate in the North Section of the Wenshan-Malipo Fault

摘要:

文山—麻栗坡断裂位于青藏高原东南缘块体运动的前锋部位，地处川滇块体、华南块体和印支块体结合地带，研究其新构造活动特征对认识青藏高原东南缘的运动格局具有重要的科学意义。卫星影像上断裂北段线性特征清晰，沿线新生代盆地呈串珠状分布。据野外地质调查，白沙坡、热水塘一带多个第四纪剖面揭示出自晚更新世以来活动的证据，发育在盘龙河T2阶地上的白沙坡断层断错了晚更新世末期阶地堆积，其被错地层14C测试年龄为15420±40 a。该断裂运动性质以右旋走滑为主兼有一定的正断分量，据阶地堆积物变形数据估算其水平滑动速率为1.6~1.9 mm/a。

Abstract:

The Wenshan-Malipo fault is located at the forefront of the block movement in the sourtheastern margin of the Qinghai-Tibet Plateau. It is located in the combination zone of Sichuan-Yunnan block, South China block and Indochina block, The neotectonic activity characteristics of this fault are of great scientific significance as they help us understand the movement pattern in the southeast margin of the Qinghai-Tibet Plateau. On satellite images, the linear characteristics of the northern segment of the fault are clear visible, and the Cenozoic basin along the fault is distributed in a string of beads. Based on the field geological survey, it has been observed that several Quaternary profiles along Baishapo and Reshuitang revealed evidence of activities since the Late Pleistocene. The Baishapo fault has developed on the terrace 2 of the Panlong River, was faulted on the terrace accumulation at the end of the Late Pleistocene. According to the 14C sample dating , the age of the faulted strata of the fault is (15420±40) a. The fracture is predominantly dextral strike-slip with a positive faulting component. The estimated horizontal sliding rate is 1.6~1.9 mm/a based on the deformation data of the terrace accumulation.