Rapid fluvial incision along the Yellow River during headward basin integration

The onset of rapid exhumation along the high relief margins of orogenic plateaux is often used as a proxy for the timing of surface uplift. However, processes that inhibit incision by rivers, such as spatially variable rock uplift, orographic changes in rainfall and channel damming by glaciers or landslides may lead to exhumation that significantly lags surface uplift. Here we reconstruct the timing, rate and pattern of fluvial incision along the Yellow River in northeastern Tibet using stratigraphic, geochronologic and geomorphic data from sedimentary basins along the present-day river course. We find that the onset of fluvial incision occurred substantially later than the onset of mountain building, 14-8 million years (Myr) ago. Fluvial incision initiated at the plateau margin 1.8 Myr ago and progressed upstream at a rate of approximately 350 km Myr -1. We conclude that the fluvial incision was a result of a climatically driven expansion of lake systems in the region that led to lake spillover and consequently the integration of the modern Yellow River.