FOLDS AND FAULTS ACTIVITY CHARACTERISTICS IN THE WESTERN END OF HEXI CORRIDOR AND ITS SIGNIFICANCE TO THE EXTENSION MODEL OF THE NORTHERN MARGIN OF THE TIBET PLATEAU

The west end of the Hexi Corridor(North Qilian Shan) is located on the northeastern edge of the Tibet Plateau, where there are three sets of active structures with different strikes developing, including NNW, NW, and almost EW-trending structures. They not only have strike-slip faults, but also have thrust faults and folds. In order to better understand the geometric features and kinematics of these activity structures, we use field geological surveys, remote sensing image interpretation, aerial photo image analysis, geomorphological mapping, terrain profile measurements, and 10 Be exposure age dating to study the Hanxia-Dahuanggou fault, the Laojunmiao anticline-Yumen fault zone, the Baiyanghe fold-Bainan fault zone, northern Kuantan Shan fault and the Hongliuxia fold in detail. At the same time, combined with GPS observation data and deep seismic reflection profiles, and other predecessors research results, we comprehensively analysis geometry of the west end of the Hexi Corridor on the shallow surface. The results show that the three groups of different strikes active structures developed at the western end of the Hexi Corridor, belong to the same tectonic system, which is mainly controlled by the extruding of the Qilian Shan to NE direction, while the Altyn Tagh fault serves only as a coordinated effect in the area. Simultaneously, the development of these active structures reveals that Tibet Plateau continues to expand in the northeast direction through a series of strike slip faults, thrust faults and folds deformation.