艾比湖流域抛物线沙丘表层沉积物粒度特征

Grain Size Distribution of the Parabolic Dunes' Sediments in the Ebinur Lake Basin,Xinjiang,China

对艾比湖流域抛物线沙丘表层沉积物样品的实验分析结果表明:沙丘表层沉积物粒径分布在0.4~2 116.5μm。沙丘表层沉积物主要成分为沙,且含有一定量的细砾和黏土成分;平均粒径从两翼间地至丘顶逐渐变粗,丘顶至背风坡脚逐渐变细;沉积物分选性整体较差,平均粒径愈小,分选性愈好;粒径频率曲线为正偏、基本对称、负偏和极负偏混合存在。沙丘表层沉积物的平均粒径与分选系数存在不显著的负相关性,与峰态呈现显著负相关,分选系数与峰态呈现显著正相关性。沙丘不同地貌部位沉积物的粒级、平均粒径、分选系数呈现出有规律的变化,系风沙流、沙丘形态、植被和沉积物综合作用的结果。艾比湖流流域内抛物线沙丘的物质来源为两个或两个以上的沉积物混合形成的多源供应物。

Based on experiment analysis of the surface sediments samples of the parabolic dunes in the Ebinur Lake Basin,the grain size of the sand dunes was between0.4μm and 2 116.5μm.The main components of the dunes sediments were sand,and it also contained a certain amount of fine gravel and clay.The average grain size gradually became coarser from the inter-dune to dune crest,and then became finer until lee slope toe.The sorting were overall poor,the smaller the average particle diameter was,the better sorted.Frequency curve of grain size were mixed of positive bias,the basic symmetry,negative bias and extreme negative bias.The grain size and sorting coefficient showed no significant negative correlation,the grain size and kurtosis coefficient showed a significant negative correlation,while sorting coefficient and kurtosis coefficient showed a significant positive correlation.The grain size,sorting coefficient and frequency curve of the different parts of dune landform sediments showed a regular change,which was the result affected by airflow, dunes morphology,vegetation cover and sediments character.The parabolic dunes sediments of the Ebinur Lake Basin were supplied by two or more sources.