民勤县固定与半固定沙丘粒度特征分析

Grain Size Characteristics of Fixed and Semi-fixed Dunes in Minqin County

沉积物粒度特征可以反映沉积物形成的沉积环境、沉积过程和搬运营力、搬运过程等信息。以民勤县西北部半固定与固定沙丘为研究对象,运用粒度分析方法,对其表层沉积物进行了系统采样分析。结果表明,半固定、固定沙丘的粒度组成均以细沙为主,极细沙次之,二者粒级级配相似,含量却有不同。半固定沙丘平均粒径为2.69Φ,中等分选近对称中等峰度分布;固定沙丘平均粒径为2.66Φ,中等分选近对称尖窄峰度分布。半固定、固定沙丘平均粒径与偏度存在二次多项式关系(R2=0.404 1);峰度与平均粒径、标准离差、偏度呈不显著线性正相关关系(0.550,0.496,0.356);标准离差与平均粒径、偏度之间无相关性。

Grain size characteristics of aeolian sediments can provide lots of information about sedimentary environment and process,sediment transporting forces.This paper selected the semi-fixed and fixed dunes at Minqin County as research objects,and studied the sediment samples systematically using the grain size analysis method.The results indicated that fine sand is dominant in the semi-fixed and fixed dunes surface sediments,and the very fine sand follows;the grain size compositions of semi-fixed and fixed dunes are similar,but difference in contents of components can be detected.The mean diameters of semi-fixed and fixed dunes are 2.69 Φ and 2.66 Φ respectively with similar sorting and skewness features,showing nearly symmetrical distribution patterns when moderately sorted.The analysis of the grain size parameters showed that a quadratic polynomial relationship（R2=0.404 1） exists between the mean diameter and skewness,but insignificant linear correlation can be found among kurtosis and the mean diameter,the sorting feature,kewness show（0.550,0.496,0.356）,and the sorting feature and the mean diameter,skewness are uncorrelated.