关键词: 活断层, 临潼-长安断裂, 第四纪, 活动性

Abstract:

The Lintong-Chang'an Fault zone locates in the middle part of Cenozoic Weihe depression.It is the boundary fault controlling the Lishan diamond block and Xi'an sag.The landforms are obviously different between the sides of the fault,and the geomorphic forms are stepped fault scraps and loess scraps.In the paper,by field geological survey to the Zhongdi Village,Wangjiabian Village and Qiaogou profiles on the Lintong-Chang'an Fault,and in combination with the dating data of regional loess and paleosol profile(An Zhi-sheng and Sun Jian-zhong),the fault is studied in order to explore the times of its latest activity and the characteristic of its late Quaternary movement.The fault strikes NE as a whole and is characterized with tensile vertical movement.The fault obviously offset the first paleosol layer S₁ in loess stratum,indicating that it is still active since late Pleistocene epoch.But most fault displacements are less than 2m,the slip rate is low,and the activity level is higher in the northern and central segments than that in the southern segment of the fault.Regarding that the Lintong-Chang'an Fault consists of several secondary faults,its whole activity should be much higher than the local slip rate of the fault we have derived.The fault displacements show an increasing trend with depth and the slip rates calculated using the dating data of different strata are almost the same.So perhaps,the fault is mainly dominated by vertical creep-slip since the late of middle Pleistocene epoch.

Key words: active fault, Lintong-Chang’an fault, Quaternary, activity