沙质草原槽形风蚀坑表面沉积物粒度特征

Particle Size Variation in Trough Blowout on Sandy Grassland

通过对呼伦贝尔沙质草原槽形风蚀坑表面沉积物粒度的观测分析,发现活跃发展时期的槽形风蚀坑沙物质总体结构以中沙为主,其次是细砂,粗砂和粉沙含量很少,且不含砾石。由于沙源沉积物粒度组成比较均一,风蚀坑各部位粒径频率曲线均呈单峰对称(或近对称)。响应于风力侵蚀和堆积,在粒度诸参数中,粗沙和细沙含量,频率曲线众数粒径,以及平均粒径等发生了明显的变化。该研究结果作为表面气流的响应,支持了先前提出的槽形风蚀坑动力学过程。

Sediment samples collected in blowouts were analyzed. Results indicate that particle size and sorting parameters vary systematically with blowout position. Sediment in a trough blowout is mainly composed of medium and fine sand, with less coarse sand and silt. No gravel is observed in the trough blowout. Because of relatively uniform composition of sediment particles, frequency curve varying with different depths of the trough blowout show the single peak symmetry. In response to wind erosion and accumulation, the contents of coarse sand and fine sand, the plural size for frequency curve, and the average particle size change significantly. The results testify the flow models of blowout.