Abstract:
The characteristics of grain composition,moisture content rule and their environmental information of sand layers were discussed by analyzing the samples collected from the leeward slope of mega-dune (with a height of close to 420 m) with vegetation distribution located at the southeast of Badain Jaran desert and west of Hohejilin lake. The results showed that the average diameter of sediments in mega-dune′s leeward slope is larger than other deserts. Soil layers with water content of 3%~5% appeared in the middle part and lower part of four sampled sections with 4 m depths. Vegetation development also indicated soil layers with high moisture content existed at the flat part of mega-dune, and the water contained by soil layer can move down, which proved that rainfall is part of the supplement sources for lake and ground water in this region. The crude grain size of surface layer in upper vegetation belt indicated the sediments are accumulated by wind recently, and the mega-dune was still move, which are also verified by vertical distributions of average diameter and grain composition of four sampled sections. Grain size changed obviously with depth for four sampling sections, which reflecting the fluctuation of wind power. The average diameter increased from lower to upper for sampled sections with high elevation, which proclaimed the increasing trend of mega-dune movement. The ratios of fine sand content and medium sand content in sections with high altitude are larger than that in sections with low altitude, which indicating the wind power changed from strong to weak in a long-time scale.
