东昆仑断裂东段下热尔断裂活动特征初步研究

下热尔断裂位于巴颜喀拉块体东北边界变形带即东昆仑断裂带东段与迭部-白龙江断裂2条剪切断裂之间挤压变形带内,在空间上属于“玛曲空段”范围.经野外考察及遥感资料验证,确定下热尔断裂走向为310°,长度约为20km,运动学特征表现为左旋走滑为主兼少量倾滑分量,沿断裂发育大量断错地貌,水平位移主要分布在3.5～5m,而未发现垂向断错地貌;垂直断裂走向开挖2处探槽,揭示断层切穿晚第四纪地层,被地表沼泽相泥炭层覆盖,结合相关地层年龄资料,初步得出平均水平滑动速率约为6.3mm/a.该断裂在几何学与运动学方面与东昆仑断裂带具有较好的一致性,推测两者之间存在一定相关性,属于东昆仑断裂带走滑断裂体系内的一条次级断裂或过渡性断裂.

A preliminary study on the Xiareer fault of the east Kunlun active fault

The Xiareer fault, located in the deformation bands of northern and eastern boundary of the Bayan Har block, is situated in the compressive zone between the east Kunlun active fault and Diebu-Bailongjiang fault, also known as the "Maqu seismic gap". Based on the field investigation and remote sensing data validation, it is confirmed that the Xiareer fault is a left- lateral fault with slight dip-slip components trending 310o and extending about 20km. A large amount of horizontal offset landforms distribute along the fault, with a latest left-lateral strike-slip of 3.5 ~ 5m, free of vertical offsets. Two trenches excavated along the direction perpendicular to the fault reveal that the fault cuts through the Late Quaternary stratum, covered with palustrine peat-layer on the surface. The relevant data ageing study reveals that the horizontal left-lateral slip-rate is approximately to 7. Imm/a. The fault has a good coherence in the kinematics characteristics with the Maqu fault of East Kunlun Active Fault, and it is possible that the Xiareer fault is closely interrelated with the East Kunlun Active Fault, as a subsidiary fracture belonging to the east Kunlun active fault.