Grain-size study of aeolian sediments found east of Kumtagh Desert

摘要

A grain-size study was conducted on the surface sediments found east of Kumtagh Desert and its connected geomorphic units, such as the wadi, wetland, oasis, and alluvial fan. The frequency, cumulative curves, and scatter diagrams of four grain-size parameters, namely, the mean grain size, sorting, skewness, and kurtosis, were plotted to study the grain-size characteristics of each sediment. Multiple discriminant analyses were applied to distinguish the deposition environments. Results indicated large diversities in the sediments from different environments. The aeolian sediments from the sandy desert and the gobi land show uniform characteristics or homogeneous changes. The sand resources from the eastern part of the desert can be considered as the alluvial deposits from the southern Altyn Tagh Mountain carried by several erosion gullies. Meanwhile, the western Mingsha Megadune inherited sediments from the nearby Danghe River. The discriminant functions proposed by Sahu can distinguish the deposition process. However, these functions lose their accuracy when applied to heavily eroded aeolian and gobi sediments.