浑善达克沙地沙粒特征及其沉积环境

对浑善达克沙地进行野外考察和采集表层沙样，通过激光粒度仪测量其沙粒粒径，分析其内部不同区域沉积物粒度特征、空间分异规律和沉积环境，为治理该沙地提供理论依据。结果表明，浑善达克沙地内部不同区域表层沉积物粒度组成上有较大的差异，总体以细沙和中沙为主，平均含量分别为43.9%和34.72%；粉沙、极细沙、粗砂含量较少。中值粒径从西到东逐渐变细；分选系数为0.94Φ，分选性整体较差，沿盛行风向有变好的趋势；偏度和峰度均值分别为0.16和1.23。粒度频率曲线指示该沙地沉积环境多样，沉积过程复杂。中西部沙物质以河流及湖泊沉积为主；东部则主要分布风成沉积，其部分物质可能来源于沙地内部的河流碎屑物或更西部的河湖相沉积。

Grain Size Analysis and the Sedimentary Environment in Otindag Sandy Land

In this study,surface sediment samples were collected from different areas of Otindag sandy land and the grain size was measured by laser particle size analyzer to examine the distribution characteristics and sedimentary environment.The results showed that there existed significant differences in the grain size composition of surface sediments in different areas in Otindag sandy land.The surface sand samples were mainly fine and medium size sands,accounting for 43.9%and 34.72%,respectively.The contents of silty and coarse sands were far lower than the fine and medium size sands.The content of medium size sand gradually decreased from west to east.The sorting coefficient was 0.94Φ,and the overall sorting features were poor,which tended to get better along with the direction of prevailing wind.The values of the mean skewness and kurtosis were 0.16 and 1.23,respectively.The grain size frequency curve indicated that the sedimentary environments and the deposition process in the sandy land were complex.The sand sample located in central and western Otindag sandy land was mainly lacustrine or river environment,aeolian deposits were mainly distributed in the east,some of which may come from the fluvial debris inside the sandy land or the fluvial and lacustrine sediments in the west area of the sandy land.