Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China
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 p...
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MDPI AG
2023-08-01
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| author | Huaying Wu Zhongcheng Jiang Qibo Huang Funing Lan Hongwei Liao Tengfang Li Chenhui Huang |
| author_facet | Huaying Wu Zhongcheng Jiang Qibo Huang Funing Lan Hongwei Liao Tengfang Li Chenhui Huang |
| author_sort | Huaying Wu |
| collection | DOAJ |
| description | 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 K<sub>2</sub>O weathering and Al<sub>2</sub>O<sub>3</sub> increasing. Therefore, the weathering degree of carbonate weathering cover was mainly determined by the leaching of K<sub>2</sub>O and the increase of Al<sub>2</sub>O<sub>3</sub>. 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. |
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| spelling | doaj.art-f8178aa850594bb5bd267e626eb99f612023-11-19T03:23:01ZengMDPI AGWater2073-44412023-08-011516294410.3390/w15162944Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest ChinaHuaying Wu0Zhongcheng Jiang1Qibo Huang2Funing Lan3Hongwei Liao4Tengfang Li5Chenhui Huang6Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaInstitute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaInstitute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaInstitute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaInstitute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaInstitute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaInstitute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, ChinaThe 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 K<sub>2</sub>O weathering and Al<sub>2</sub>O<sub>3</sub> increasing. Therefore, the weathering degree of carbonate weathering cover was mainly determined by the leaching of K<sub>2</sub>O and the increase of Al<sub>2</sub>O<sub>3</sub>. 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.https://www.mdpi.com/2073-4441/15/16/2944geochemistryweathering coverresiduaCIAweathering and residual processcarbonate rocks |
| spellingShingle | Huaying Wu Zhongcheng Jiang Qibo Huang Funing Lan Hongwei Liao Tengfang Li Chenhui Huang Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China Water geochemistry weathering cover residua CIA weathering and residual process carbonate rocks |
| title | Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China |
| title_full | Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China |
| title_fullStr | Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China |
| title_full_unstemmed | Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China |
| title_short | Geochemistry of Weathering Cover and the Main Influencing Factors in Karst Area of Guilin, Southwest China |
| title_sort | geochemistry of weathering cover and the main influencing factors in karst area of guilin southwest china |
| topic | geochemistry weathering cover residua CIA weathering and residual process carbonate rocks |
| url | https://www.mdpi.com/2073-4441/15/16/2944 |
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