Late Cenozoic extension structure in Baingoin-Shuanghu area of central Tibet and its dynamic mechanism

In central Tibetan Plateau, besides the NS-tranding extension structure after late Cenozoic, a series of nearly EW-striking extension structures, controlled by EW-trending normal faults, were found during the field work. Geomorphology was characterized by the parallel-relief valleys separated by the relatively narrow ridges and the rift-ridge landform. The DEM analysis shows that the EW-tranding extension structure cutting the NS-trending Shuanghu basin in the study area. Studies of the fault kinematics, chronology and sedimentation in the fault-controlled basin suggest that the activity of the EW-trending normal faults began in the Miocene and these faults were probably developed alternately with the NS-trending extension structure. Furthermore, with the increasing of the elevation of central Tibetan Plateau, the activity of the EW-trending faults were obviously strengthened in Quaternary. The gravity action on the high-standing plateau resulted in the development of grabens in different directions.