Abstract: There are few aeolian geomorphology researches about Sanlongsha area located in the Northern Kumtagh Desert. After analyzing the grain size of surface sediment samples in Sanlongsha area, the paper aims to discuss the characteristics differences of the different dune types and geomorphological positions. Results show that the mean grain size ranges from 0.95 Φ to 1.89 Φ; sorting coefficient varies from 0.55 to 1.55; main components of deposits are fine sand and moderate sand, and both of which content reach 63.20%. It is coarser and worse sorted than sands in the Kumtagh Desert and Taklamakan Desert in China, and has a coarser grain size on global scale. The main types of sand dunes in Sanlongsha area are barchans or dune chains and linear dunes developed in the north. On the surface of these two typical dune types, the average grain size both belongs to moderate, the grains become coarser and better sorted from the bottom of the dune to the crests, and the coarsest sands are found at the crests, with the mean grain size 1.64 Φ and 0.71 Φ, respectively, which is different from the pattern in other areas, the finest sands occurring at the crests. The cumulative probability curve is two-stage or three-stage for drifting dunes while three-stage or four-stage for granule ripples and denudation monadnock, which indicates the latter has experienced shorter sorting process. The paper can provide some useful information for analyzing the material sources and formation processes of aeolian geomorphology in Sanlongsha area and also for revealing the relationship between Sanlongsha and Kumtagh Desert.

Key words: Kumtagh Desert, Sanlongsha, sediment, grain size, aeolian geomorphology