Erosion rate in the Shapotou area, northwestern China, constrained by in situ-produced cosmogenic 21Ne in long-exposed erosional surfaces

Abstract

Erosion at the Earth's surface is a major factor controlling the landscape evolution. Cosmogenic nuclides provide a valuable tool for the quantitative study of surface erosion. We employ cosmogenic nuclide 21Ne analysis to quantify the average erosion rate in the Shapotou area, at the northeastern margin of the Tibetan Plateau, based on the steady-state erosion model. A series of erosional surfaces on the river terraces generated by the Yellow River incision offer us a new approach to determine whether the cosmogenic 21Ne nuclide inventory has reached equilibrium between nuclide production and loss by surface erosion. Using the steady-state 21Ne concentration, the average erosion rate in this area is determined to lie between 0.54 ± 0.11 cm ka−1 and 0.72 ± 0.21 cm ka−1. A depth profile of the subsurface cosmogenic 21Ne concentrations provides additional evidence for the validity of our steady-state erosion model. Our results reveal that the erosion rate in this area lags significantly behind the incision rate of the Yellow River, which increased the local relief in the Shapotou area.