关键词: 新月形沙丘, 粒径与分选参数, 沙坡头, 腾格里沙漠

Abstract: The 69 sand samples were collected and analysed from crescentic dunes developed on different geomorphological sub-environment such as banks of Yellow River and main part of southeastern Tengger Desert in the vicinity of Shapotou District, Ningxia. The results show grain size and sorting parameters varies systematically with not only position of the dunes but also geomorphologic location of these dun es. The mean grain size decreases and standard deviation increases from the main part of the desert to the southern terrace of Yellow River. It was also found t hat two-distinct patterns of grain size variation across a dune profile as well as other types of dune such as linear dunes in other desert. The first is that crestal zones of the dunes in the main part of Tengger Desert composes of finer and better sorted than both windward and lee flanks. The second, the crest sand is coarser but still better sorted than any other position of dunes in the banks of the Yellow River. According to analysis of the interrelation between grain size parameters and other environmental conditions, the mechanics of grain size variation and some skewness characteristics of dune sands have been discussed in this paper.

Key words: crescentic dune, grain size and sorting, Shapotou, Tengger Desert