Detrital zircon U-Pb ages from geomorphology surfaces in the middle reaches of Yellow River

The Yellow River is one of the rivers in the world with the largest sediment runoff, with the middle reaches of the Yellow River being an important link between the Qinghai-Tibet Plateau and the North China Plain, and even the Bohai Sea and the Yellow Sea for material transport. Understanding the material transport pattern of this section of the Yellow River is crucial to solving the problems of sediment accumulation in the lower reaches of the Yellow River, which is prone to breakouts and diversions. Detrital zircon U-Pb spectrum is widely used as an important provenance tracer in the river sediments of the world. Previous studies of coarser sediments (>40um) in the modern riverbed of the middle and upper Yellow River suggest that the modern Yellow River can barely transport material from upstream to downstream. This study extends the range to >20um grains and uses sediment source tracing on the geomorphic surface combined with chronology to reveal the formation process and material transport pattern of the Yellow River from the Jinshaan Gorge to the Sanmen Gorge section.

The study shows that the main source of material in the Jinshaan Gorge section of the Yellow River has been from the surrounding mountains and the bedrock within the gorge since its formation. Since the Holocene, increased surface erosion within the Chinese Loess Plateau and headward erosion by local rivers have brought material from the western part of the Chinese Loess Plateau. In the Sanmen Gorge section, the discrepancy between the ancient eastward-flowing rivers and the modern Yellow River material source reveals the formation of a pattern in which headward erosion of local rivers cut through Sanmen Gorge and led to the eastward flow of the Yellow River into the sea.