Mid-Miocene initiation of the Aimunike-Oulongbuluke Range in the NE Qaidam Basin, implications for the growth of the Tibetan Plateau

摘要

Constraining the initial age of the Northern Qaidam Thrust Belt is critical for studying the growth of the Tibetan Plateau. This study presented insights from field observations and seismic profiles, to constrain the structural pattern and the initial age of the eastern segment of the Northern Qaidam Thrust Belt during the Cenozoic. Our research suggested the Aimunike and the Oulongbuluke uplifts, as well as the Ounan Depression between them have been uplifted during the mid-Miocene, and as a result underwent widespread denudation to remove the late Eocene-early Miocene sequences over them. After that, this area was subsided and accepted the deposition of the mid-Miocene to the Pliocene strata. A second phase of thrusting occurred in the Quaternary as those faults initiated in the mid-Miocene rejuvenated. Our results together with the previous studies suggested the N-S compressional stress over the NE Tibetan Plateau strengthened substantially during the mid-Miocene, leading to a widespread plateau growth at that time.