贵州岩溶区镶嵌景观上覆土层的粒度分布特征及其指示意义

THE GRAIN-SIZE DISTRIBUTING FEATURES OF SOIL LAYERS ON A CARBONATE-NONCARBONATE ROCK CONTACT KARST LANDSCAPE IN GUIZHOU PROVINCE AND THEIR INDICATION

通过对贵州岩溶区喀斯特镶嵌景观中碳酸盐岩与碎屑岩相互接触部位剖面的粒度分布特征综合对比、分析研究,结果表明:不同岩石上覆土层之间的粒度频率曲线和粒度参数存在明显的差异,仅在两种岩石类型的接触过渡带显示出一定混合特征,且与区域其它岩类上覆土层没有关联性;各土层粒度分布特征与下伏基岩有着密切的联系,显示出继承性。同时,进一步肯定了粒度分布特征在贵州岩溶区上覆土层的物源指示意义。

Our previous study on carbonate rock weathering crusts in Xiangxi and Guizhou indicate that it is powerful to demonstrate residual genesis of soil layer by using grain size parameters. In this paper, we select limestone weathering and other sediment or sedimentary rock weathering profiles in Wudang and Zhazuo, which are contact with each other, to measure grainsize parameters. The results show that, in a section, grain size frequency curves between the soil layers and acidic insoluble material from overlying bedrock are consistent, having nothing to do with other soil layers or bedrocks. It indicates inheritance of weathering crust deriving from bedrock. Furthermore, the diagrams of grainsize parameters, such as average value, standard deviation, skewness and kurtosis, reflect that different sections have different range respectively. In short, based on the grainsize characteristics, the soil layers which overlying different bedrocks are different, inheriting to its bedrock obviously. And it proves again that this method is an important tool to discern the origin of the soil layer on contact karst landscape in Guizhou. 