关键词: 西秦岭北缘断裂带, 水平位移, 微地貌, 特征事件

Abstract: The western Qinling Fault zone is one of the main left-lateral strike-slip active faults in northeastern Tibet. At site of Huangxianggou, the behavior of the fault zone shows typical strike-slip movement. Detailed analysis on the amounts of the offset of the late Quaternary landforms and geologic bodies along the fault shows that at Huangxianggou the maximum horizontal displacement since the late of late-Pleistocene is about 40～60m, and the minimum is 6～8m which is possibly the amount of one principal slip associated with one large earthquake event. And it is also inferred that the amounts of the displacement along the fault can be grouped, and between the groups there is a stable increment of 6～8m. The grouping and the increment of amounts of the offsets suggest that this fault segment displays an activity associated with characteristic earthquakes, and the 7 groups of the displacement values represent 7 characteristic events on the fault. Analysis on the microgeomorphology related to the faulting, such as periodic sag-ponding and deformed pluvial fans, also suggests the corresponding events. Thus it can be inferred, the activity of the fault zone has been dominated by several strong movements since late Late-Pleistocene.

Key words: western Qinling Fault zone, horizontal displacement, microgeomorphology, characteristic events