The dissolution mechanism and karst development of carbonate rocks in karst rocky desertification area of Zhenfeng–Guanling–Huajiang County, Guizhou, China

Abstract

The phenomenon of rocky desertification is obvious in karst plateau of Guizhou, China, and the distribution area of slight–medium–severe rocky desertification is very large in Zhenfeng–Guanling–Huajiang, Guizhou. To explore the cause of formation and development of rocky desertification in the region, the karst development mechanism and characteristics were studied by the method of indoor dissolution test and microscopic analysis. The results show that the dissolution and karst features of carbonate rocks are closely related to geological structure, hydrogeological conditions, and lithology. The dissolution rate is the most affected by the chemical composition and mineral composition, followed by the pore structure and the particle feature. The dissolution rate of carbonate is in positive proportion with the calcite content, while it decreases with increasing content of dolomite. In the same chemical composition, the rock with the finer grains has a faster surface dissolution rate. In addition, the erosion amount will change with the pore aperture and connectivity. Karst morphology is mainly affected by the microstructure and mineral assemblage characteristics of carbonate rocks. In this rocky desertification area, bare rock over a large area will be further eroded, which will form the stone bud, stone forest. At the same time, the hydrodynamic effect of groundwater will erode the rock deeply, and the depression, karst funnel, or deep valley will appear gradually.