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<p>This study assesses the bauxite potential of Nyambaka, located near the Minim-Martap on the Adamawa plateau, one of the bauxite deposits of the Cameroon volcanic line. Twenty-one samples of rock and its weathering cover were collected along a 22-metre-deep pit and submitted to petrography, XRD diffraction, and chemical analyses by ICP-AES and ICP-MS. Upwards, the profile varies from basanite to saprolite, mottled clay, carapace, and duricrust. Porphyritic basanite displays olivine phenocrysts embedded in a matrix of pyroxene, plagioclase, opaque crystals and glass. The lateritic mantle is made up of various amounts of kaolinite, gibbsite, magnetite, goethite, hematite, and anatase. Chemically, basanite displays high concentrations of SiO<sub>2</sub>, Fe₂O₃, Al₂O₃, CaO, and MgO, whereas other oxide contents are &lt; 3 wt%. Along the profile, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, MnO, and TiO<sub>2</sub> contents increase while other oxides are leached. Trace element concentrations increase except leached Rb and Sr. REE spectra show no Ce or Eu anomalies except those of the duricrust that display a strong positive Ce anomaly and plot below the basanite. This evidences a change from reducing to oxidizing conditions where CeO<sub>2</sub> precipitates while other REEs are leached. Weathering through monosiallitisation, allitisation and complex migration-accumulation yielded iron-rich bauxites, clayey bauxites, and bauxite iron ores. Bauxitization process was coupled with ferruginisation. Al₂O₃ and Fe<sub>2</sub>O<sub>3</sub> concentrations throughout this Nyambaka profile are in the interval of economic thresholds. Thus, it can be considered as a polymetallic indice.</p>

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Mineralogical and geochemical evolution of the lateritic weathering profile on the Nyambaka basalt, Adamawa-Cameroon: implication to bauxitization process

  • 期刊论文

  • 发表日期：

    2026年2月2日

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  • Marie Alex Akaba Chimeu,
  • Calistus Gentry Fuh,
  • Alex Fotso Kengne,
  • Mathieu Nouazi Momo,
  • Rose Yongue-Fouateu,
  • Charles Nkoumbou

摘要

This study assesses the bauxite potential of Nyambaka, located near the Minim-Martap on the Adamawa plateau, one of the bauxite deposits of the Cameroon volcanic line. Twenty-one samples of rock and its weathering cover were collected along a 22-metre-deep pit and submitted to petrography, XRD diffraction, and chemical analyses by ICP-AES and ICP-MS. Upwards, the profile varies from basanite to saprolite, mottled clay, carapace, and duricrust. Porphyritic basanite displays olivine phenocrysts embedded in a matrix of pyroxene, plagioclase, opaque crystals and glass. The lateritic mantle is made up of various amounts of kaolinite, gibbsite, magnetite, goethite, hematite, and anatase. Chemically, basanite displays high concentrations of SiO2, Fe₂O₃, Al₂O₃, CaO, and MgO, whereas other oxide contents are < 3 wt%. Along the profile, Al2O3, Fe2O3, MnO, and TiO2 contents increase while other oxides are leached. Trace element concentrations increase except leached Rb and Sr. REE spectra show no Ce or Eu anomalies except those of the duricrust that display a strong positive Ce anomaly and plot below the basanite. This evidences a change from reducing to oxidizing conditions where CeO2 precipitates while other REEs are leached. Weathering through monosiallitisation, allitisation and complex migration-accumulation yielded iron-rich bauxites, clayey bauxites, and bauxite iron ores. Bauxitization process was coupled with ferruginisation. Al₂O₃ and Fe2O3 concentrations throughout this Nyambaka profile are in the interval of economic thresholds. Thus, it can be considered as a polymetallic indice.