Contrast of geochemical features of the typical weathered profiles in Guizhou Plateau

Guizhou Plateau is located in the east of the Yunnan-Guizhou Plateau, where variable karst landscapes are widely distributed. Typical silicate weathered profile (Deng Jiawan profile) and carbonate weathered profile (Pingba profile) in the karst area are selected as the main studying objects. Based on the study on the element’s distribution and the chemical weathering intensity, it is found that: the content of SiO2, Fe2O3, Al2O3 are the highest components at the two profiles, but the distribution of the major chemical components are significantly different, which is led by the difference in parent materials; there are significant differences between the values of the chemical index of alteration (CIA) at the two profiles, which illustrates that the stages of chemical weathering are different, the weathering at Deng Jiawan profile is moderate while very strong at Pingba profile, and the intensity and trend of the weathering are significantly different; CIA reflect the differences of the parent materials, the degree of chemical weathering and the chemical compositions at different soil profile; the strong weathering results in abnormal enrichment of REE at the two profiles, but distribution patterns of REE are also significantly different; and the formation of the profiles are due to the weathering of their own bed rock, but not influenced obviously by the loess in North China.