Grain size characteristics in the Hexi Corridor Desert

- Sand sea material is very fine and fine sand.
- There is linear relationship between sand material parameters.
- Dune formation material includes aeolian and lacustrine sediment.
- Lacustrine sediment provides material for windward toe and stoss formation.
- Aeolian sediment provides material for crest and leeward toes formation.

This study investigates grain-size characteristics on the dune surfaces in the Hexi Corridor Desert, a little-researched area of northwestern China. Grain-size parameters (mean, standard deviation, skew, and kurtosis) were determined on dune surfaces at the windward toe, stoss, crest, and leeward toe. Multiple discriminant analyses were applied to distinguish deposition environments. Results indicated that the aeolian sediment in the Hexi Corridor Desert is mainly composed of very fine and fine sand (0.07 mm ± 0.01 to 0.24 mm ± 0.06). Sorting improves as grain size becomes finer. However, mean grain size increased with skew, but decreased with kurtosis. There is a good negative correlation between skew and sorting. However, there is no correlations between sorting and skew, and skew and kurtosis. The sediment deposition environment includes aeolian, lacustrine and alluvial sediments. The lacustrine sediment provides the source material for the formation and development of dune windward toes and stoss, but the aeolian sediment provides the source material for the formation and development of dune crest and leeward toes. Based on log-probability of grain size distributions, aeolian sediments in dune networks are composed of two distinct saltation populations. Sand sources affect the mean grain size changed from upwind to downwind, medium sand decreases and fine sand, very fine sand, and silt and clay increase, sand sediment become finer from upwind to downwind. There are three types of mean sand grain sizes over dune surface: coarser crest (69%), finer crest (24%), or no difference (7%) with windward slope and leeward slope.