库姆塔格沙漠粒度分布特征及环境意义

库姆塔格沙漠位于中国西北干旱区，被称为我国第六大沙漠。粒度分析在区分沉积环境、判定物质输运方式、判别水动力条件和分析粒径趋势等方面具有重要作用。对库姆塔格沙漠中北部、北缘、西部、中间及南部、东南缘5组20个沙样粒度分析结果表明：其粒度组成差异很大；粒度参数具有以下特征值：平均粒径Mz=1.55～2.92 Φ；标准偏差σ1=0.41～1.11；偏度SK1=-0.11～0.31；峰态KG=0.77～1.23。同时，粒度频率曲线呈单峰态和多峰态共存状态；大部分沙样的偏度近于对称。分析结果说明库姆塔格沙漠沉积物的沉积环境复杂多样，有风力沉积、河湖沉积、河流冲积(洪积)等。

Characteristics of Sand Granularity from Kumtag Desert and Its Environmental Significance

Kumtag desert located at the northwest arid area of China is known as the sixth largest desert of China. Method of grain size analysis plays important role in sedimentary environment differentiation，hydrodynamic condition distinguishing, and grain size trend analysis, etc. Analyzing results to 20 sand samples taken from middle-northern, north margin, western, middle and southern, southeast margin of Kumtag Desert show that there are remarkable differentiation in grain-size distribution, and the mean parameters are as follows: median diameter Mz=1.55~2.92 Φ, the standard deviation σ1=0.41~1.11, skewness SK1=-0.11~0.31, kurtosis KG=0.77~1.23. The grain size frequency curves of the samples have characteristics of single peaks or multi-peaks; most of the sand skewness is nearly symmetric. The analytical results reveal that the sediments in Kumtag Desert are complex and diverse, having aeolian, lacustrine and alluvial（proluvial）sediments river and so on.