关键词: 天山北麓 库松木契克山山前断裂 几何结构 垂直位错

Abstract: Thrust fault is the basic model of crustal deformation and also one of the major structural forms of orogenic belts, indicating the tectonic environment of compression. Most of the catastrophic earthquakes that affect human activity lie within the plates. For the interior of the plate, as long as there is compressive stress in the regional sense or under some local tectonic conditions, reverse faults may occur. It is considered that the south-north compression caused by the collision of The Indian plate and the Eurasian plate is the main reason for the formation of the present tectonic framework on both sides of the North-south Tianshan Mountains. The continuous shortening and thickening of the earth's crust has made the active structure of The Prequaternary period of Tianshan mountain extremely developed. Meanwhile, the new nappe structure in the front of Tianshan Mountain is also the main site for the development of medium-strong earthquakes in the current Tianshan Mountain area, and its seismogenic mode is mostly blind fault slope - slip surface - surface fault slope. The northern Tianshan inverse fault-fold belt is located at the junction of the northern foothill of Tianshan Mountain and Junggar Basin, among which the Kusongmuqike piedmont fault is located in the south of Jinhe County, and is an important thrust active fault belt in the western northern Tianshan Mountain. In recent ten years, there have been many earthquakes with magnitude of 5.0 or above in the eastern section of the fault zone. A detailed study of the geometric distribution and tectonic geomorphologic features is helpful to understand the tectonic deformation characteristics and regional strain distribution in the Tianshan Area since the late Quaternary. By means of high-resolution remote sensing image interpretation, uav aerial survey and differential GPS terrain profile survey, combined with field geological survey, the results show that the eastern segment of the Kusong Muqike piedmont fault is composed of two secondary reverse faults.Among them, the south branch new longkou fault by 5 en echelon distribution of faults, the overall trend NW, S, inclination of vertical, about 48 km, dislocation piedmont fault phase 2 pluvial fan and 5 river terraces, terrace of T1 / T2 and latest fan3 activity times, fault scarp 3.6 m to 4.7 m high, for the fault activity in the same product, T3-T4 terrace vertical displacement of 13.5 m and 20.3 m respectively, vertical displacement and terrace around T5 terrace fan2 pluvial fan, about 30 m. The upper fault passes through no structural deformation, and the surface retains the original geomorphic form. The faults of the North branch hydrological Station are distributed in an intermittent manner. The overall strike is nearly EW, with a total length of about 44km, and the faulted multi-stage alluvial-diluvial fan. On the alluvial-diluvial fan of Fan3, two near-parallel positive scarps are developed in the northern margin of the alluvial-diluvial fan, while other faults cut through the alluvial-diluvial fan and the surface gully, forming steep reverse scarps on the surface. To scarp slope height accumulation is the measure of the vertical displacement of the 17.23 m, 0.29 m minimum vertical displacement, scarp highly concentrated between 4.72 ~ 9.85 m, reverse fault scarp maximum vertical displacement between 7.78 ~ 9.80 m, minimum scarp height is 2.43 ~ 3.05 m, scarp highly concentrated between 3.25 ~ 9.19 m, scattered development of multiple faults between the two groups of faults, scarp height range 0.5 ~ 1.0 m.As far as the height distribution of the steep-ridge is concerned, its vertical displacement has a distribution law of decreasing from west to east. These results contribute to further understanding of the strain distribution pattern in the western part of the Northern Tianshan.

Key words: The northern foot of Tianshan, Kusongmuqieke Mountain Front Fault, Geometry , Vertical displacement