In situ cosmogenic 10Be, 26Al, and 21Ne dating in sediments from the Guizhou Plateau, southwest China

Landscape evolution is modulated by the regional tectonic uplift, climate change, and river dynamics. However, how to distinguish these mechanisms through the research of surface exhumation and fluvial incision remains controversial. In this study, cosmogenic 10 Be, 26 Al, and 21 Ne concentrations in quartz from cave deposits, modern river sediments, and bedrocks were measured to constrain the applicability of cosmogenic 21 Ne and discuss Quaternary landscape evolution history in the Guizhou Plateau, southeast China. Using the 26 Al- 10 Be and 21 Ne- 10 Be pairs to distinguish the cosmogenic 21 Ne concentration from the excess 21 Ne, we found that the nucleogenic 21 Ne produced by the U and Th decay in quartz is significant in the samples although there is the possibility of inherited cosmogenic 21 Ne. Combining with previous studies, we suggest that the precise approach for applying the cosmogenic 21 Ne could be reached by (1) estimating the contribution from nucleogenic 21 Ne, (2) avoiding samples with complex burial histories to exclude inherited cosmogenic 21 Ne, and (3) combining the 10 Be- 26 Al- 21 Ne nuclides method for the Quaternary samples. In addition, both pre-burial basin denudation rates and burial ages derived from the 26 Al- 10 Be pair were used to determine the different timescale surface denudation rate and fluvial incision rate in relation to previous work. The consistency of the different timescales pre-burial basin denudation rate, 36 Cl surface denudation rate, and modern basin denudation rate indicates that the landscape-scale surface denudation has been likely stabilized since the Quaternary in the Guizhou Plateau area. The slightly higher river incision rates than the local surface denudation rate show that the river dynamics may not have reached a steady-state due to the regional tectonic uplift in the Guizhou Plateau.