Radiometric dating for recent lake sediments on the Tibetan Plateau

We present radiometric data from nine lakes across the Tibetan Plateau, and compare their reliability in relation to recent research. Unsupported ²¹⁰Pb profiles show, except for one particular lake, non-exponential decline of ²¹⁰Pb activity with sediment depth. Stratigraphic dates based on global atmospheric nuclear weapons maximum fallout of ¹³⁷Cs (1963) support the use of the constant rate of ²¹⁰Pb supply (CRS) model in four of the dated cores. The discrepancy in the others is likely due to recent increased input of catchment-derived ²¹⁰Pb. ²¹⁰Pb dates in this study suggest that post depositional diffusion of ¹³⁷Cs activity has been significant. The practice of assigning early 1950s dates (start of global atmospheric thermonuclear testing) to lake sediment sequences on the Tibetan Plateau should be used with caution. ¹³⁷Cs profiles from Tibetan lake sediment cores and their geographical distribution suggest that ¹³⁷Cs derived from the 1986 Chernobyl accident or atmospheric testing in China was not sufficient to form a significant peak effective for dating.