- 责任者：Yu Jingxing (State Key Laboratory of Earthquake Dynamics ; Institute of Geology ; China Earthquake Administration ; Beijing 100029 ; China) ; Zheng Wenjun
- 刊名：Seismology and Geology
- 出版年：2013
- 卷期：35(4)
- 关键词：断裂 ; fractures ; 运动学 ; kinematics ; 阿拉善盆地 ; Alxa Basin
- 页码：p.731-744
- 图表：9 illus., 41 refs.
- 分类号：0300
- issnNo：ISSN0253-4967
- isbnNo：CN11-2192/P
The Yabrai range-front fault is a normal fault,which is about 120km long,trends N60°E and distributes along the southeast margin of the Alashan block.In this paper,we focus on the geomorphology and kinematics of the Yabrai range-front fault,and discuss the implications of the fault for the regional tectonics.This fault consists of three segments and the most active one is located in the southwest,which has a length of about 35km.The about 1 ～ 2m-high scarp,stretching almost the full segment,might be the result of the latest earthquake event.Fresh free surface indicates that the elapsed time of the last event should not be long.The middle segment is about 31km in length.The results suggest that just a single fault is developed along the piedmont of the Yabrai Shan,and there is no evidence of recent activity on this fault.In contrast to the simple geometric structure of the middle segment,the northeast segment consists of several faults.The scarps of the most recent earthquake event,which are clear but discontinuous,are about 0.5 ～ 1.5m high and some are up to 2m.Although the scarps along the southwest and northeast segments of the fault are similar,it is difficult to suggest they are caused by the same earthquake without precise dating.The seismic reflection profile suggests that the Yabrai range-front fault came into being as a normal fault in Cretaceous,when the Tibetan plateau did not emerge at that time.Therefore,we conclude that the Yabrai range-front fault is not the consequence of the Indo-Asian collision.But this region plays a great role in constraining the tectonic evolution of the Alashan block and therefore,the Tibetan plateau.