Active faults and magnitudes of left-lateral displacement along the northern margin of the Tibetan Plateau

The norlem margin of the Tibetan Plateau (NMTP) is a major intracontinentual Cenozoic transpressional zone that comprise, a series of active strike-slip faults and thrust faults. It is important to document cumulative horizontal displacements along the NMTP in order to understand quantitatively strain partitioning in East Asia since the India-Eurasia collision. Based on an analysis of horizontal slip along major active faults, the total amount of horizontal displacements is estimated up to 700 km between the Tibetan Plateau and the Tarim Basin since the convergence of India and Eurasia. Along the western and middle segment of the Altyn Tagh fault to the northern margin of the Qaidam Basin, there are abundant evidence that show that the net displacement is similar to400 km since 40-35 Ma, and along the Shulenan Shan and southeast of middle Qilian Shan since 25-17 Ma, the amount of offset is similar to150 km. The largest horizontal slip in Qilian Shan-Hexi Corridor to the northeast of the Altyn Tagh fault is also similar to150 km since late Oligocene to early Miocene. It decreases to only similar to60 km along the Haiyuan fault (since late Miocene) and to 25 km. along the Zhongwei-Tongxin fault since the Pliocene (about 5.3-3.4 Ma), at the northeast margin of the Tibetan Plateau. This clearly implies northeastward diminishing of the total horizontal displacement and temporal getting younger of the fault slip along the NMTP. However, this tendency is very complicated at different times and different segments as a result of the uplift, growth and rotation of different segments of the NMTP at different stages during the convergence of India and Eurasia. (C) 2004 Elsevier B.V. All rights reserved.