• 责任者：Du Jianjun (Key Laboratory of Neotectonic Movement and Geohazard ; Ministry of Land and Resources ; Beijing 100081 ; China) ; Li Dunpeng
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(5)
• 关键词：古滑坡 ; fossil landslides ; 陕西 ; Shaanxi Province
• 页码：p.1005-1015
• 图表：4 illus., 1 table, 39 refs.
• 分类号：1800
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     The study area is located in transition zone between the Qinling orogenic belt and Weihe basin of the southeast in Ordos block,is about 15km east of Huaxian,Shaanxi Province.Huashan piedmont fault is a crust-structural and geomorphologic boundary between the Qinling orogenic belt and the east of Weihe basin.The loose-accumulated breccia,in an area of 4-6km2 occurs under the loess in north-part of Huashan piedmont fault,Lianhuasi area in Huaxian.There are several viewpoints of origin of loose-accumulated breccia under loess.According to the field survey of landform characteristics and deposits,the authors prefer the viewpoint of high-speed remote landslide.We found that the landslide is composed of slide bed,slip,sliding surface,the posterior wall of the landslide,landslide perimeter,landslides depression and so on; the landslides can be divided into early and late two stages,and collapse superimposed in late stage landslide.Early stage landslide is corresponding to the chair circle landscape in hilltop of Zhangjiashan,breccia is deposits in Baiya Lake hole depth 60.10m to 70.23m,with a thickness of 10.13m.Late stage landslide corresponds to lower chair circle landscape in the southern of Baoyu valley,breccia is deposits in Baiya Lake hole depth 33.74-50.15m in thickness of 16.41m.What is the age of late stage landslide？Most researchers think that it is associated with MS=5 1/2 Huaxian earthquakes of November 3,1072 or MS=8 Huaxian earthquakes of January 23,1556.However,we find that the maximum thickness of loess covered in the landslides is up to 9m during the field investigation,so,it must be formed in at least the tens of thousands years ago according to the Quaternary loess accretion rate projections.In order to constraint accurately the age of Lianhuasi landslides of Huaxian,Shaanxi Province,we gather 17 OSL samples from loess accumulated above late stage landslide in five cross section selected,breccia were collected.We carried out OSL dating of bottom of the loess cover on landslides from five cross section are from 130.2±5.6ka to 187.3±7.7ka,it means that bottom loess cover on landslides formed in different time,it may be related to the ancient landform.The oldest age have been get 187.3±7.7kaB.P., it represent the late stage landslides of Lianhuasi of Huaxian formed in 187.3kaB.P.ago.It is the first time to accurately obtain the upper boundary of age of late landslides of Lianhuasi of Huaxian,this paper reports that it is the oldest highspeed and runout landslide in China,it is of a very important significance in landslide research.So that,the reasonable interpretation of Huaxian Lianhuasi landslides is induced by seismic activity of Huashan piedmont fault.