Cenozoic paleostress field of tectonic evolution in Qaidam Basin, northern Tibet

Abstract

This article analyzes the stress fields in the Qaidam Basin since the entire Cenozoic using finite element numerical simulations. The stress fields are investigated by analyzing tectonic joints and the GPS velocity field in the basin. The relationship between the stress field patterns and the tectonic activity of the basin was discussed. Based on previous research on the uplift of the Tibetan Plateau, five stages of the tectonic evolution of the Qaidam Basin are modeled. The simulation results show that the stress trajectories in the Oligocence and the Pliocene–Quaternary were similar. In the Oligocence, the stress trajectories in the basin changed significantly and were mainly controlled by the compressional stress on the southern boundary in the initial stage. As the compressional stress on the northern boundary of the basin gradually increased, the compressional stress on the southern and northern boundaries had equal effects in the intermediate stage, and the compressional stress on the northern boundary mainly controlled the stress trajectories in the late stage. During the uplift of the Tibetan Plateau, the stress trajectories in the Qaidam Basin experienced an apparent reversal. The stress trajectories of the internal basin rotated clockwise from NE–SW to NW–SE in the Oligocence and which gradually changed to counterclockwise from NW–SE to NE–SW in the Miocene and recovered to clockwise from NE–SW to NW–SE in the Pliocene–Quaternary.

Keywords

• qaidam basin
• paleostress
• finite element numerical simulation