Cenozoic evolution of the Qaidam basin and implications for the growth of the northern Tibetan plateau: A review

As the largest depression in the Tibetan plateau, the Qaidam basin preserves over 10 km thick of Cenozoic sediments. Those sediments represent a unique archive of the evolution of the northern part of the Tibetan plateau and of intracontinental deformation in general. Yet, several critical issues associated with the evolution of the Qaidam basin remain controversial, preventing a full understanding of the evolution of the northern margin of Tibet during the Cenozoic. Here we comprehensively review these issues, synthesize records from structural geology, sedimentology, geochronology, and geophysics, and finally propose a holistic view of the Cenozoic evolution of the Qaidam basin. We infer that: 1) the traditional age model that assigned a Paleocene to Eocene basal age to the Cenozoic strata in the basin seems to fit reasonably well the deformation history obtained from combining growth-strata observations and thermochronology data across the basin; 2) basement-involved faults, with both dip-slip and strike-slip components, developed within the Qaidam basin. In particular, the Neogene initiation of strike-slip faulting along the south-dipping faults that roots into the Eastern Kunlun Shan played an important role in the evolution of the southern Qaidam basin; 3) The Eastern Kunlun Shan was already exhumed during the deposition of the Lulehe Formation, serving as a significant source of clastic material deposited in the Qaidam basin and separating the latter from the Hoh Xil basin to the south. We conclude that the Qaidam basin is a superimposed sedimentary basin that successively experienced flexural subsidence, outwards expansion, isolation and partitioning during the Cenozoic. Finally, the Cenozoic evolution of the basin results from a tight interplay between tectonics and climate.