GYIG OpenIR  > 矿床地球化学国家重点实验室
Element mobilization and redistribution under extreme tropical weathering of basalts from the Hainan Island, South China
Ke Jiang;  Hua-Wen Qi;  Rui-Zhong Hu
2018
Source PublicationJournal of Asian Earth Sciences
Volume158Pages:80-102
Abstract

Chemical weathering of rocks has substantial influence on the global geochemical cycle. In this paper, the geochemical profile of a well-developed basalt weathering profile (> 15 m thick, including soil, saprolite, semiweathered rock and fresh basalt) on the Island of Hainan (South China) was presented. The soil and saprolite samples from this profile are characterized by high Al2O3 and Fe2O3 concentrations (up to 32.3% and 28.5%, respectively). The mineral assemblage is dominated by kaolinite, Fe-oxides/-hydroxides and gibbsite (or boehmite), indicating extensive desilicate and ferrallitic weathering. The acidic and organic-rich environment in the soil horizon may have promoted elemental remobilization and leaching. The strongest SiO2 depletion and Al2O3 enrichment at about 2.4 m deep indicate that the main kaolinite hydrolysis and gibbsite formation occurred near the soil-saprolite interface. The mild Sr reconcentration at about 3.9 m and 7.1 m deep may be attributed to secondary carbonate precipitation. Mn-oxides/-hydroxides precipitated at 6.1 m deep, accompanied by the strongest enrichment of Ba and Co. Uranium is mildly enriched in the middle part (about 7.1 m and 9.1 m deep) of the weathering profile, and the enrichment may have been caused by the decomposition of uranyl carbonates or the accumulation of zircon. Immobile element (i.e., Zr, Hf, Nb, Ta, Th and Ti) distributions at different depths are mainly controlled by secondary Fe-oxides/-hydroxides, and follow the stability sequence of Nb ≈ Ta ≈ Th > Zr ≈ Hf > Ti. The limited thickness (∼15 cm) of the semi-weathered basalt horizon at the rock-regolith interface (15.28 m deep) suggests that plagioclase and pyroxene are readily altered to kaolinite, smectite and Fe-oxides under tropical climate. The marked enrichment of transitional metals (such as Cu, Zn, Ni, and Sc) along the rock-regolith interface may have associated mainly with increasing pH values, as well as the dissolution of primary apatite and formation of secondary phosphates. Our findings highlight the importance of secondary phosphates in the redistribution of transition metals, and in the possible Mg, Cu, and Ni isotopic fractionation under extreme weathering of basalt in tropic climate.

KeywordChemical Weathering basalt secondary Minerals hainan Island (South China)
Indexed BySCI
Language英语
Document Type期刊论文
Identifierhttp://ir.gyig.ac.cn/handle/42920512-1/8704
Collection矿床地球化学国家重点实验室
Affiliation1.State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
2.University of Chinese Academy of Sciences, Beijing 100049, China
Recommended Citation
GB/T 7714
Ke Jiang;Hua-Wen Qi;Rui-Zhong Hu. Element mobilization and redistribution under extreme tropical weathering of basalts from the Hainan Island, South China[J]. Journal of Asian Earth Sciences,2018,158:80-102.
APA Ke Jiang;Hua-Wen Qi;Rui-Zhong Hu.(2018).Element mobilization and redistribution under extreme tropical weathering of basalts from the Hainan Island, South China.Journal of Asian Earth Sciences,158,80-102.
MLA Ke Jiang;Hua-Wen Qi;Rui-Zhong Hu."Element mobilization and redistribution under extreme tropical weathering of basalts from the Hainan Island, South China".Journal of Asian Earth Sciences 158(2018):80-102.
Files in This Item:
File Name/Size DocType Version Access License
Element mobilization(3896KB)期刊论文作者接受稿开放获取CC BY-NC-SAView Application Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[Ke Jiang;Hua-Wen Qi;Rui-Zhong Hu]'s Articles
Baidu academic
Similar articles in Baidu academic
[Ke Jiang;Hua-Wen Qi;Rui-Zhong Hu]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[Ke Jiang;Hua-Wen Qi;Rui-Zhong Hu]'s Articles
Terms of Use
No data!
Social Bookmark/Share
File name: Element mobilization and redistribution under extreme tropical weathering of basalts from the Hainan Island, South China.pdf
Format: Adobe PDF
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.