贵州高原地区典型风化剖面地球化学特征及其对比研究

选取了贵州高原喀斯特地区的典型硅酸盐风化剖面(毕节邓家湾剖面)和碳酸盐岩风化剖面(安顺平坝剖面)作为研究对象,以贵州地区的铝土矿剖面和中国黄土作为对比,对其元素分布特征及化学风化作用和强度与进行了研究。结果表明:SiO2、Fe2O3、Al2O3均为两个剖面含量最高的组分,但由于成土母质的化学组分不同,元素分布差异比较明显;同时由于经历的化学风化阶段并不相同,两个剖面的化学蚀变指数(CIA)值相差较大,邓家湾剖面经历了中等强度的风化作用,而平坝剖面的风化强度则十分强烈,CIA反映了土壤剖面的化学组成的差别,以及成土母质、风化成土过程和程度上的差异;虽然两个剖面稀土元素总量都较高,但配分模式存在着明显的差异,剖面的形成基本上是由于各自基岩的风化作用形成的,受中国黄土的影响并不明显。 

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 land- scapes are widely distributed. Typical silicate weathered profile（Deng Jiawan profile） and carbonate weath- ered 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 composi- tions at different soil profile; the strong weathering results in abnormal enrichment of REE at the two pro- files, but distribution patterns of REE are also significantly different; and the formation of the profiles are due to the weathering of their own bedrock, but not influenced obviously by the loess in North China.