Reconstruction of Aeolian Activity Variability in the Central Tibetan Plateau From Grain-Size Distributions: End-Member Modeling and Source Attribution of Sediments From Lake Selin Co

Abstract

The grain size analysis and end-member modeling of clastic fractions in the Selin Co basin sedimentary sequence have been revealing variations of aeolian activity in the central Tibetan Plateau since 3,900 cal yr BP. The grain-size distributions measured in this study were classified into three statistical end-members that may be connected to clastic material inputs from a variety of sources and transport processes. Among these, the EM3 fraction (modal grain size of ∼138 μm) was suggested to indicate the aeolian activity history in the central Tibetan Plateau. The results indicate that the aeolian activity in this region occurred under dry and cold conditions since 3,900 cal yr BP, with three strong aeolian activity intervals at 3,200–2,900 cal yr BP, 2,400–1,400 cal yr BP, and after 130 cal yr BP. Comparison with other records showed that solar insolation, weakening Indian summer monsoon, and the strengthening westerlies have a direct relationship with the aeolian activity in the central Tibetan Plateau. We therefore suggest that the atmospheric circulation patterns and effective humidity may have a strong impact on the water balance and weathering intensity in the arid and semiarid areas, hence affecting dust emissions. Also, the coarse detrital end-member fraction of lake sediments is suggested as a potential aeolian activity proxy.