华南沿海黄色粉土沉积的激光粒度分析及其成因讨论

在华南沿海地区的低矮丘陵及台地上，广泛发育一套黄色粉土堆积。对该区7个典型剖面进行系统的激光粒度分析，并与典型黄土以及研究区常见的海、河相沉积进行对比。结果表明，华南沿海各黄色粉土剖面均以10～50 μm的粗粉砂为众数粒组，<5 μm的粘粒为次众粒组，分别对应风成黄土的“基本粒组”和“挟持粒组”，岩性均属于粘土质粉砂。样品的粒度参数、粒度散点图、频率分布曲线、粒度指数特征均显示为典型的风成成因。粒度判别分析结果为负值，同样证实了黄色粉土的风成特性。华南沿海黄色粉土的各项粒度特征指标及其所反映的沉积类型、沉积环境均与我国典型黄土具有较好的可比性，而与研究区的海、河相沉积截然不同。

Laser Particle Size Analysis and Genesis of the Yellow Silt in the Coastal Area of South China

A layer of yellow silt is widely distributed on the low hills and platforms in the coastal area of south China. Seven typical sections in the study area were analyzed using laser grain size analysis to determine the sedimentary characteristics and genesis of the yellow slit. The typical loess, marine and fluvial deposits were also adopted for contrastive study. The results showed that the yellow silt sections were all featured by the modal size group of coarse silt (10~50 μm) and the secondary grain size of clay (<5 μm), which were corresponding to the “basic grain size group” and “second grain size group” of the typical loess, and the lithology were clayed silt. Aeolian characteristics of the yellow silt were further indicated by grain size parameters, scatter diagrams, frequency distributional curves and grain size index. The result of grain size discriminant analysis was negative, also supporting an aeolian origin of the yellow silt. All of the grain size characteristics of the yellow silt and the sedimentary type and environment they reflected were comparable to that of the typical loess, but quite different from associated fluvial and marine deposits.