青海西南部乌丽活动断裂系的地质特征及灾害效应

Geological features and hazard effects of the Wuli active fault system on the northern Qinghai-Tibet Plateau

乌丽活动断裂系发育于乌丽山地,是青藏高原北部重要的区域性活动构造体系,由乌丽北山活动断裂、乌丽盆缘活动断裂和乌丽南山活动断裂所组成,主要包括17条不同规模、不同性质的活动断层。大部分活动断层属左旋斜滑断层,部分活动断层为左旋走滑断层。据地质观测资料估算,典型活动断层全新世左旋走滑速度分量为1.2～3.5mm/a、垂直下滑速度分量为0.5～3.5mm/a。沿乌丽活动断裂系发育5条宽100～400m的构造裂缝带、大量串珠状冰丘群与少量移动冰丘,构造裂缝产生的高密度地表破裂和移动冰丘造成的地表拱曲变形是影响青藏铁路、公路线路工程安全的主要地质灾害。

located in the Wuli Mountains ,the Wuli active fault system is an important regional active tec-tonic system of the northern Tibetan Plateau.It consists mainly of 17active faults of different scales and natures.Most of the active faults are left-lateral oblique-slip ones and part of them are left-lateral strike-slip ones.According to field observations ,it is estimated that the left-lateral strike-slip rate and vertical slip rate of some typical active faults are1.2-3.5mm /a and0.5-3.5mm /a respectively.Five100-400m wide surface fracture zones,many bead-like ice hummock swarms and some migrating ice hummocks are developed along the Wuli active fault system.High-density surface rupturing produced by structural fissures and surface domal deformation caused by migrating ice hummocks are main geological hazards affecting the safety of the Golmud-Lhasa railway,highway and pipeline.