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Cobalt enrichment in a paleo-karstic bauxite deposit at Yunfeng, Guizhou Province, SW China

2020; Elsevier BV; Volume: 117; Linguagem: Inglês

10.1016/j.oregeorev.2019.103308

1872-7360

Yongzhen Long, Anhuai Lu, Xiangping Gu, Guoxiang Chi, Lin Ye, Zhongguo Jin, Dongliang Zhang,

Clay minerals and soil interactions

Cobalt can be enriched in a variety of different geologic settings, while it is mainly produced as a by-product of sediment-hosted stratiform Cu deposits and magmatic Ni-Cu deposits associated with mafic and ultramafic rocks. In this study, we report elevated Co concentrations in a paleo-karstic bauxite deposit at Yunfeng, Guizhou Province. Whole-rock chemical analyses indicate that Co is concentrated in carbonaceous ferruginous clay layers (167–962 ppm, average 383 ppm, n = 5) and siderite layers (47–439 ppm, average 213 ppm, n = 7) within the bauxite deposit. The positive correlation between Co and S, together with petrographic and EPMA analyses, suggests that Co occurs primarily as Co-rich/bearing sulfides/sulfoarsenides rather than cobaltiferous oxides/hydroxides as in most lateritic Ni-Co deposits. Many of the Co concentrations measured in this study are higher than the minimum grade (300 ppm) or cut-off grade (200 ppm) for economic exploitation of Co from sulfides or arsenides. Basing on these results, we put forward the scientific significance of Co enrichment in paleo-karstic environments and the potential importance of Co resources (as by-products of aluminum production) in bauxite deposits.