Incision rate of the Yellow River in Northeastern Tibet constrained by 10Be and 26Al cosmogenic isotope dating of fluvial terraces: implications for catchment evolution and plateau building

摘要: Unlike other large rivers flowing out of Tibet, the Yellow River escapes from plateau towards NE crossing no less than five NW-SE striking, actively growing ranges and intervening basins. Thick Plio-Quaternary deposits fluvial terraces testify to a phase aggra- dation sediment infill up average surface elevation (3200 - 3250 m a.s.l.) Gonghe, Guide Qinghai Lake A set seven main across Gonghe Basin suggests progressive down-cutting carving 500 deep Longyang gorge at basin exit. 10Be 26Al concentrations in quartz sub-surface samples four constrain timing incision by determining burial age deposit exposure its surface. Modelling depth dependence concentration 26Al/10Be ratio allows us onset ongoing 120-250 ka. These ages suggest long-term rates between 2-6 mm/a. Together with present morphology gorge, our results imply rapid river catchment evolution interaction dynamics, tectonic climate northeastern Tibet.