武汉青山“砂山”粒度特征及其成因指示

根据代表性的武汉青山“砂山”的粒度分析探讨“砂山”的成因。结果表明:剖面砂颗粒含量较高，平均达５９％，粗粉砂约２３％，细粉砂约１１％，黏土含量少。粒度参数特征与典型沙丘砂一致，频率分布曲线为双峰，概率累积曲线为两段式，部分层位三段式，跃移质含量高，显示风积成因，Ｃ—Ｍ图及结构参数散点图与河流沉积物差别明显，判别分析结果正负夹杂。综合看来，“砂山”是末次冰期时出露的河流沉积物经风力吹扬、搬运，在长江南岸堆积而 成。

Grain Size Features and Genesis of the Qingshan "Sand-dune" in Wuhan

Based on the grain-size analyses of representative section of Qingshan "sand-dune" in Wuhan,the causes of "sand-dunes" is discussed in this paper.The results show as follows: Qingshan "sand-dune" mainly consists of sand with the average content over 59%,while 23% coarse silt and 11% fine silt approximately,only little in clay content.The characteristics of grain size parameters is the same as typical sand dune,frequency distribution curves with two crests,and probability cumulative curves with a pattern of two segments,partly three,and high content of saltation load,closely resemble that of eolian sediments,C-M chart and statistical indices of grain size distribution different with fluvial sediment obviously,the discriminant analysis result is mingled with plus-minus.With a brief calculation,"sand-dunes" are fluvial sediment which outcropped in the last glaciation blown and conveyed by wind,then deposit in the south bank of Yangtze River.