Affiliation:
1. Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China
2. Key Laboratory of Karst Dynamics, Ministry of Natural Resources & Guangxi Zhuang Autonomous Region, Guilin 541004, China
Abstract
The chemical weathering of carbonate rocks is the main form of interaction between earth spheres in the karst critical zone. The karst weathering cover, which is composed by residua from carbonate rocks weathering, contains important information about the climate environment and material cycle. We present the chemical composition of weathering covers in karst area of Guilin, Guangxi province, analyze their weathering process and strength, and compare them with the other weathering covers in other karst area in China, including Yunnan, Guizhou, Hunan, and Qinghai Tibet Plateau. The results showed: (1) the chemical composition of Guilin weathering covers were similar to that of carbonate weathering covers in other areas of China, and had the common characteristics of uniform distribution of chemical composition in the profile and obvious enrichment of Fe, Al and trace elements. During the formation of carbonate weathering cover and the residua, the rapid dissolution of Ca and Mg had an important impact on the migration and enrichment of other elements. (2) The chemical index of alteration (CIA) of carbonate weathering covers in Guilin and other karst areas of China was much larger than that in the upper crust (UCC) (60.13), which showed strong chemical weathering characteristics of the humid and hot climate. (3) The weathering process of carbonate rock was different from that of silicate and loess. In the early stage of carbonate rock weathering, soluble components (calcite and dolomite) had been rapidly dissolved and leached. All the carbonate weathering residua was measured to be in the stage of K2O weathering and Al2O3 increasing. Therefore, the weathering degree of carbonate weathering cover was mainly determined by the leaching of K2O and the increase of Al2O3. As a result, there was no correlation between CIA and Na/K (molar ratio), but was a significant negative correlation between CIA and K/Al (molar ratio) in the carbonate weathering cover. (4) The CIA values of weathering residua and carbonate weathering cover in southern China were negatively correlated with latitude, reflecting the influence of climate factors. From the influence of lithology, the chemical compositions of parent rock can affect the CIA of weathering cover, and the content of insoluble matter in carbonate rock was negatively correlated with CIA. From the influence of topography, the CIA value of weathering residua decreased from the high to the low position and from the shallow to the deep part of the profile.
Funder
Study on the influence mechanism of karstification on the migration of trace elements in soil water of peak-cluster depression
Subject
Water Science and Technology,Aquatic Science,Geography, Planning and Development,Biochemistry
Reference44 articles.
1. Evaluating the effects of terrestrial ecosystems, climate and carbon dioxide on weathering over geological time: A global-scale process-based approach;Taylor;Philos. Trans. R. Soc. Lond.,2012
2. Liu, C. (2007). Biogeochemical Processes and Surface Material Circulation: Erosion and Biogenic Factor Circulation in Southwest Karst Basin, Science Press.
3. Chemical Weathering, Atmospheric CO2, and Climate;Kump;Annu. Rev. Earth Planet. Sci.,2000
4. Global CO2 Consumption by Silicate Rock Chemical Weathering: Its Past and Future;Zhang;Earths Future,2021
5. Weathering pattern of amphibolites in the different climate zones from Western Dharwar Craton, Southern India;Mehta;Arab. J. Geosci.,2021
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献