Abstract:The north fringe fault zone of Aerjin mountains is an important fault in Aerjin fault system (Altyn Tagh fault system).It might have existed in Late Proterozoic and became the boundary fault between Talimu Plateform and paleo-ocean plate in Paleozoic.In the neotectonic movement it has had very intense activities particularly left-lateral strike-slip movement.In this paper its notheastern sector is studied.
On this sector of the fault zone a thick fault gouge belt and a wide cataclastic rock belt were observed.The plane distribution of the fault zone often exhibits an echlon or oblique connexion pattern.The deformation and some specific geomorphic features caused by strike-slip movement of fault are given.
According to a great deal of data of the displacement distance on water system and other geomorphic unit we obtained four average slip rates from diffirent times in late Quaternary to today.They are 5.8mm/yr.from Middle Pleistocene,3.4-4.0mm/yr.from the lntersadial of middle Pleistocene,4.0-4.5mm/yr.from Late Pleistocene,and 8.0mm/yr.from Holocene.Based on C14 dating,the rate is more than 3.6mm/yr.from late Holocene.
In the northeastern sector we found some paleoseismic traces and afresh paleoearthquake deformation belt in Lucaogo,where we estimatedthat the earthquake occurred about 300 years ago and M=7.0-7.5 according to the slope of fault scarps and length of fracture belt.The relationship between recent seismicity and the fault zone,the seismic risk and great earthquake recurrence are discussed.
