关键词: 毛乌素沙地, 新月形沙丘, 抛物线形沙丘, 粒度特征

Abstract:

The grain size composition of dunes is mainly determined by wind regimes， sand sources， and the interaction between dune morphology and airflows. The grain-size composition of sand dunes can reflect the formation process of different types of dunes. Samples were collected from 0-5 cm of the surface layers at the foot of the windward slopes， the dune crests， and the foot of the leeward slopes of 20 barchan or dune chains and 25 parabola dunes in the Mu Us Desert. The grain-size composition of the samples was tested and analyzed to explore their grain size characteristics. The results show that： （1） There are no significant differences in grain-size composition and parameters between barchan dunes and parabola dunes， and the grain -size frequency distribution curves are typical single-peak shapes， but compared with barchan dunes， the parabolic dunes have worse sorting and higher suspended components； The windward slope of parabola dunes has worse sorting and higher coarse sand content than barchan dune. （2） In the statistics of grain-size distribution patterns of sand dunes， the barchan dunes tend to have the finest grain-size on the windward slope， accounting for 65%， whereas the parabolic dunes tend to have the finest grain-size on the leeward slope， accounting for 56%；The grain-size frequency distribution curve also indicated the biased results of the grain-size distribution patterns. （3） Vegetation， the opposite morphology of barchan dunes and parabola dunes and their interaction with airflows are the main factors that cause the differences in grain-size characteristics between the two types of dunes.

Key words: Mu Us Desert, barchan dune, parabolic dune, grain size characteristics