Late Cenozoic uplift-exhumation history of the Altyn Tagh and Qilian Mountains: Evidence from detrital apatite fission track thermochronology
Xu Qinqin1,2, Ji Jianqing2, Zhao Wentao2, Sun Dongxia2, Zhong Dalai3, Zhao Lei1
1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037;
2. Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871;
3. Institute of Geology and Geophysics, Chinese Academy of Science, Beijing 100029
The Altyn Tagh and Qilian Mountains define the northern boundary of the Tibetan Plateau. Their uplift-exhumation history in the Cenozoic records the deformation and northward propagation of the Tibetan Plateau, which is important to explore the uplift dynamics of the Tibetan Plateau. Using apatite fission track(AFT)analysis on detrital samples, this paper attempts to reveal Cenozoic uplift-exhumation history of the Altyn Tagh and Qilian Mountains statistically. AFT dating resuts suggest that the mountain ranges experienced four stages of uplift and cooling during the Late Cenozoic: 21.1~19.4 Ma, 13.5~10.5 Ma, 9.0~7.3 Ma, and 4.3~3.8 Ma. The youngest cooling event only took place within the Qilian Mountain. The uplift-exhumation of 9.0~7.3 Ma was perversive in the study area, resulting in the present geomorphology of Altyn Tagh and Qilian Mountains. Regional data show that a large-scale regional uplift of mountains in the northern and eastern edges of the Tibetan Plateau and even the whole western China occurred at 9~7 Ma(or 8~6 Ma)at which time the "high-west" landform of China was initially formed. The four uplift and cooling events are coeval with the uplift stages of the Tibetan Plateau, which should be response to the India-Eurasia collision.