藏南格仁错地区孜桂错断裂的第四纪活动及其构造意义

因印度板块与欧亚板块碰撞,第四纪时青藏高原的拉萨地体内部出现一系列南北向的正断层,拉萨地体的北边界出现一系列近东西向的走滑断层.孜桂错活动断裂就是这些走滑断层中具有典型意义的一条,其活动表现为右行走滑,断裂切过河流、冲积扇、废弃的湖岸等,断裂的水平位移从10 m到375 m不等.它转换连接朋曲-申扎正断层和喀喇昆仑-嘉黎剪切带;同时,孜桂错断裂本身也是喀喇昆仑-嘉黎剪切带的重要组成部分.它的活动反映拉萨地体内部的东西向伸展以及羌塘地体相对拉萨地体的向东运动.

QUATERNARY ACTIVITY OF ZIGUICUO FAULT IN GAYRINGCO AREA, SOUTH XIZANG, AND ITS TECTONIC IMPLICATIONS

During the collision between the India and Eurasia plates, the movements in the interior of the blocks and relative moving among these blocks occurred in the Qinghai Xizang (Tibet) Plateau. The former is represented by the south north strike normal faults within the Lhasa Block and the latter by some right lateral strike slip faults along the northern margin of the Lhasa Block. The Ziguicuo active fault is typical one of strike slip faults, whose right lateral activities in the Quaternary cut rivers, alluvial fans and abandoned banks. The horizontal offsets of the fault range from 10 m to 375 m, and the vertical one not conspicuous. The Ziguicuo fault, being an important part of the Karakorum Jiali fault zone, connects the Pengqu Shenzha normal fault and the Karakorum Jiali fault. The activity of the Ziguicuo fault implies that the Lhasa Block might be east west extending and the Qiangtang Block might be eastward moving.