文献类型：期刊文献

英文题名：Decoupling of gallium and aluminum in bauxite deposits: Constraints from simulation experiments and Ga isotopes

作者：Zhang, Yuxu Fan, Haifeng Ling, Kunyue Zhu, Chuanwei Yang, Hong Du, Shengjiang Wen, Hanjie

第一作者：Zhang, Yuxu

机构：[1] State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; [2] School of Earth Sciences and Resources, Chang'an University, Xi'an, 710054, China; [3] College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China; [4] School of Mining Engineering, Guizhou Institute of Technology, Guiyang, 550003, China

第一机构：State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China

通信机构：School of Earth Sciences and Resources, Chang'an University, Xi'an, 710054, China

年份：2026

卷号：725

外文期刊名：Chemical Geology

收录：EI(收录号：20263821516845);Scopus(收录号：2-s2.0-105051074432)

语种：英文

外文关键词：Aluminum alloys - Aluminum hydroxide - Deposits - Gallium alloys - Gallium compounds - Mineralogy - pH - Sedimentary rocks

摘要：Given the chemical and crystallochemical similarities between gallium (Ga) and aluminum (Al), Ga is typically enriched in Al-bearing minerals (e.g., aluminum hydroxides and clay minerals) via isomorphism, resulting in a strong Ga-Al correlation in Al-rich sedimentary rocks such as bauxite. Bauxite is generally enriched in Ga and serves as the primary industrial source, contributing ～90% of global Ga production. However, some bauxites with substantial Ga enrichment exhibit notable Ga-Al decoupling, the mechanism of which remains unclear. Here, a comprehensive study was carried out on the Houcao bauxite deposit in Zunyi, Central Guizhou, SW China, which displays decoupled Ga and Al contents. Ga/Al ratios of samples from the H1 profile and the upper part of the H2 profile range from 2.30?×?10?4 to 2.93?×?10?4, broadly consistent with the range of potential source rocks (shales and carbonate rocks with ratios of 2.47–3.43?×?10?4). In contrast, samples from the lower part of the H2 profile show a gradual increase in Ga/Al ratios from 3.35?×?10?4 to 5.54?×?10?4, with the five lowermost, Ga-rich samples (Ga/Al?=?4.35–5.54?×?10?4) exhibiting pronounced Ga-Al decoupling. These decoupled samples uniquely contain pyrite intergrown with illite, indicating an acidic depositional environment. Soaking experiments show that Al is more readily leached and mobilized than Ga at pH??～6. Furthermore, the leachate is enriched in heavy Ga isotopes compared to the residues. A negative correlation between δ71Ga and Ga content in the two studied profiles suggests that isotopically heavy Ga was released during bauxite formation, leaving lighter Ga in the residual bauxites. We conclude that environmental pH is a key control on Ga-Al decoupling, with acidic conditions (pH? ? 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.