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为了探讨“巫山黄土”的成因,对剖面样品进行了粒度分析.结果表明:“巫山黄土”主要由<50μm的颗粒组成,>50μm的砂级以上颗粒平均含量为16.9%;作为风尘“基本粒组”的10～50μm的粗粉砂平均含量达43.1%,为众数粒组;5～10μm的细粉砂颗粒含量平均为14.5%;<5μm的粘土颗粒含量平均为25.5%,为次众数粒组.粒度参数、频率曲线与典型风尘沉积物相似,显示为典型的风积成因;粒度参数的C-M、L-M、A-M图等粒度象分析及结构参数散点图与现代河流沉积物差别明显,而与长江中下游分布的下蜀土却基本一致.判别分析结果绝大部分为负值,显示了风积成因为主、个别层位受到水流作用改造的成因特征.
In order to investigate the cause of “Wushan loess”, the grain size of the samples was analyzed. The results showed that “Wushan loess” mainly consisted of <50μm particles and the average content of particles above 50μm was 16.9% The average content of coarse silt of 10 ~ 50μm in the dust group “Basic Granule” was 43.1%, which was the average particle group; the content of fine silt particles of 5 ~ 10μm averaged 14.5%; the average content of clay particles <5μm was 25.5%, which is the number of second order particles. Particle size and frequency curves are similar to those of typical aeolian sediments, showing typical aeolian genesis. Particle size analysis of CM, LM, AM and other scatter plots The sediments of modern river are obviously different, but they are basically the same with the lower loess distributed in the middle and lower reaches of the Yangtze River. The results of discriminant analysis are mostly negative, indicating that the main aeolian genesis and the genetic stratification of individual horizon affected by water flow.