Particle-size Characteristics and Sedimentary Environment of Dune Sediments in Southwestern Qaidam Basin

Abstract

[Objective] The particle size characteristics and sedimentary environment of dune sediments in the southwest margin of Qaidam Basin were analyzed in order to provide basic data to support sand control and safe operation of the Golmud-Korla Railway. [Methods] We used the particle-size analysis method to determine the particle-size characteristics and sedimentary environment of dunes in the piedmont of the Southwestern Qaidam Basin. [Results] The dunes in the Southwestern Qaidam sand area were mainly composed of fine sand, followed by medium sand. The mean particle-size was between -0.14 Φ and 3.49 Φ, with an average of 2.02 Φ. The sorting parameters varied from 0.32 to 1.59 (with average of 0.66). The skewness distribution was nearly symmetric. The kurtosis was dominated by moderate kurtosis. The natural frequency distribution curves were uni-modal and bi-modal. The cumulative frequency curves were one-stage, two-stage, and three-stage. Mean particle-size and sorting showed a linear correlation relationship, i.e., as mean grain-size became finer, sorting gradually became better. Mean particle-size and kurtosis were negatively correlated when the peak kurtosis value was less than 0.9. In contrast, when the peak kurtosis value was greater than 0.9, mean particle-size and kurtosis were positively correlated. [Conclusion] The northwestern part of the Southwestern Qaidam Basin is an aeolian environment dominated by aeolian sands. The southeastern part of the area is dominated by lacustrine and alluvial-fluvial environments, and the dune sands are affected by the interaction of wind and water.

Keywords

• qaidam basin
• sand dune
• grain-size
• sedimentary environment