Study On Characteristics Of Rupture Rocks Of Lithology,Texture And Structure Of North Segment Of Yingxiu-beichuan Fault

Wenchuan Earthquake Fault Zone Scientific Drilling(WFSD) is a national sp ecial technological program,which is co-organized by Science & Technology Minis try,Ministry of Land and Resources and China Earthquake Administration.WFSD p rogram plans to carry out several scientific drilling holes in the hanging-wall of t he co-seismic surface rupture zones,the Yingxiu-Beichuan and Anxian-Guanxian fa ult zones,caused by the 2008 Wenchuan earthquake.WFSD-4S is located in the ha nging-wall of the Yingxiu-Beichuan fault zone at Nanba, Pingwu, Mianyang,Sichua n province.The hole went through the Yingxiu-Beichuan fault with the final depth of 1204.18 m.This paper focuses on the WFSD-4S by the studies of field core ca taloging,petrology,structural geology.The results show that the cores can divided int o six segments(or two rock assembled segments), including the Qiujiahe Formatio n(0~534.63m),the Youfang Formaion(534.63~872.31m),the Qiujiahe Formation(872.31~887.26m),the Youfang Formation(887.26~891.69m),the Qiujiahe Formati on(891.69~895.91m),the Youfang Formation(895.91~1204.18m),from top to bott om, respectively.The qiujiahe Formation strata mainly consists slate and carbonaceo us slate,theYoufang Formation strata are the metamorphic rock which consists of s ilty metamorphic,metamorpic fine-slitstone,calcareous silty metamorphic,and cabonae ous silty metamorphic. According to the assembled characteristics of fault-related r ocks, fault zones can be divided into symmetric or asymmetric fault zone, with th e center of fault gouge,or not.Basing on the dip angles of trench and lithological profile well log, the PSZ in the WFSD-4S should be within one of the primary f ault zone among FZ1084 and FZ1087. Compared with the 4S hole PSZ and the Beichuan fault zone, it is also known that the slip zone is the same as that of the Beichuan fault.,both of them are right strike slip movmet.But it is not the same as the south segment,the south segment is thust.