Multiple Exhumation Stages During the Cenozoic Evolution of the Northeast Tibetan Plateau

The Cenozoic growth history of the northeast (NE) Tibetan Plateau has been strongly debated in the past few years with three deformation models being proposed: progressive northeastward propagation, out-of-sequence deformation, and episodic deformation. Reconstruction of the long-term deformation and exhumation history of the different blocks can help elucidate the growth pattern and tectonic processes involved in the formation of the Plateau. Both the Qaidam and Jiuquan basins-the two largest basins of the NE Tibetan Plateau-contain continuous and well-exposed successions of synorogenic sediments that span the entire Cenozoic. We used apatite fission-track thermochronology, sedimentary facies, and structural and provenance analyses of these successions to determine the exhumation history of the Tibetan Plateau. Five distinct fast exhumation events were recognized and dated: 65-54, 43-39, 34-29, 24-21, and 16-15 Ma. Comparison with existing morphotectonic information enabled us to reconstruct a multiple-stage growth scenario for the NE Tibetan Plateau in the context of the surface uplift phases across the Himalayan-Tibetan orogen during the Cenozoic. Overall, our findings support the episodic deformation model and emphasizes that the current relief of the NE Tibetan Plateau is largely derived from these five of stage of exhumation. The Tibetan Plateau is the largest orogenic plateau on Earth, but the timing and mechanisms of its formation remain elusive. However, they can potentially be deciphered by studying the continuous sedimentary successions deposited along the margins that preserve long-term information about the spatio-temporal deformation pattern and uplift history. We present the results of high-temporal-resolution apatite fission-track records of Cenozoic continuous successions from the Qaidam and Jiuquan basins-the two largest basins of the NE Tibetan Plateau. Five distinct fast exhumation events from the Paleocene through Miocene are recognized and dated. Combined with sedimentary facies and structural and provenance analyses, together with morphotectonic evidence, our results show that the orogenic belts surrounding these basins were synchronously deformed by multiple tectonic events which resulted in the progressive surface uplift of the Himalayan-Tibetan orogen. This evolution occurred within the framework of the India-Asia convergence during the Cenozoic. Well-dated Eocene-Pleistocene sedimentary records of exhumation history from the Qaidam and Jiuquan basins Five exhumation episodes related to tectonic activity are identified from both basins and dated to the Paleocene through Middle Miocene Exhumation stages were synchronous across the NE Tibetan Plateau and a Cenozoic scenario of episodic growth is reconstructed