Particle size characterization and sources of sediments in the Uzhumqin sand dunes.

Sediment constitutes the fundamental basis for forming and evolving aeolian geomorphology. The characteristics of sediment particle size offer insights into the development and evolution of sandy terrain, making their study critical to understanding aeolian geomorphology and sand control. In this study, we combined high-density collection of surface sediments in the Uzhumqin sand dunes and GIS spatial analysis to analyze the particle size parameters and changes in the spatial distribution of surface sediments in this region. In addition, we used an end-member analysis to identify the potential sources of the sediments. The results showed that surface sediments in the Uzhumqin sand dunes had distinct spatial distributions. Medium and coarse grain sands dominated the sediments in the dunes, and the mean grain size and the sorting coefficient generally increased along the prevailing wind direction, with high values in individual areas related to factors such as material sources and vegetation cover. Skewness was strongly influenced by factors such as landform change and human activity, and spatial variability became more complex. Kurtosis and the soil fractal dimension showed generally decreasing trends along the prevailing wind direction. With dune fixation, the contents of clay and powder particles in the soil increased; the mean particle size, the sorting coefficient, and the fractal dimension of the soil gradually increased, and the skewness and kurtosis gradually decreased. The end-member analysis results indicated the existence of five end-members (EM) in the dune sediments. EM 1 was a mixed component of wind-deposited fine sands and nearby fluvial sediments. EM 2 was the main component of sediments in the study area and was the result of sorting lake sediments by wind action and by the local topography. EM 3 may be a product of river flood deposition. EM 4 and EM 5 had coarser grain sizes. EM 4 was a lake-phase sediment product influenced by topographic and vegetation cover factors, and EM 5 was primarily a river and lake sediment product modified by weathering. The sediment particle size results from the study area indicate that the sediment in the sandy region is generally coarse due to multiple factors, including topography, climate, hydrology, and human activity. Sandy material in the study area originated from nearby, with very little sand being transported from long distances. [ABSTRACT FROM AUTHOR]