酸不溶物对碳酸盐岩风化壳发育程度的影响

Through studying weathering characteristics of red weathering crusts developed on carbonate rocks from different stratum systems in.the Guizhou karst region (including western Hunan Province), and comparing with those developed on other types of bed rocks in native and ambient areas in the same climatic zone, we draw conclusions as follows: (1) In the regions where weathering is not much intense, weathering intensities of red weathering crusts of carbonate rocks are affected markedly by the components of their acid-insoluble residua, and the higher weathering maturity of acid-insoluble residue, in general, the more intense weathering degree of red weathering crust. Owing to the fact that different stratum systems have different compositions of acid-insoluble residua, weathering intensities of red weathering crusts based on them are certainly distinct. (2) Further weathering potential of weathering crust falls along with increasing of weathering maturity of acid-insoluble residue, and consequently weathering equilibrium can be reached more easily. (3) At the sharply transitional interface between rock and soil, geochemical index of acid-insoluble residua change distinctly along with leaching loss of carbonate. Therefore, the dissolution of carbonate accelerates the weathering of silicate compositions instead of retarding its decomposition. (4) Owning to occurrence of acid-insoluble residua of carbonate rocks during kaolinization and even weak laterization, weathering crusts of carbonate rock are more vulnerable to weathering than that of crystalline rocks, and show a high weathering intensity. Therefore, it is not appropriate to classify the weathering crust of carbonate into the weak weathering type, which is even much weaker than that of crystallized rock weathering types such as basalt and granite.