The topographic growth of Tibetan Plateau in Oligocene-Early Miocene: constraints on the paleo-geography and Yellow River drainage evolution

The timing of outward migration of deformation and topographic growth of the Tibetan Plateau remains a debated point. This project is aimed to identify the related uplift and exhumation processes through a combination of techniques (fission-track and U-Pb ages, trace element analysis) on apatite detrital grains collected from modern rivers and Oliog-Miocene sedimentary successions at the south-west margin of the Ordos basin. The results show that the sediments from the Yellow River and the sampled sedimentary sections sourced from the West Qinling Mountain and/or North Qilian Mountain, which, on their turn, imply that outward migration of the Tibetan Plateau was occurring at least since Early Cenozoic. The detrital signature clearly shows the evolution of different drainages, as testified by the different age patterns observed on sediments from the Wei and the Yellow Rivers. Our data demonstrate that these drainages were already identified and completely disconnected since the Oligocene-Early Miocene, thus corroborating the idea of a progressive eastward migration of the Tibetan Plateau since then.