Comparative geochemical and facies analysis of Bangam bauxite deposits, West Cameroon

Bauxite exploration in West Cameroon has relied on morphological facies description, leaving the geochemical controls on facies differentiation and protolith identity poorly constrained. This study combines geomorphological mapping, facies characterisation and whole-rock major-, trace- and REE geochemistry on 160 samples from nine sites across the Bangam North and South sectors. Bangam South develops high-grade, low-silica bauxite (Al2O3 = 38.41–50.81 wt.%; SiO2 = 1.28–1.81 wt.%), whereas Bangam North shows heterogeneous, less evolved profiles (Al2O3 = 15.12–44.96 wt.%; SiO2 = 1.97–39.30 wt.%; Fe2O3 up to 56.06 wt.%). Strong inverse correlations between Al2O3 and Fe2O3 (r = –0.98) and SiO2 (r = –0.67) reflect drainage- and leaching-controlled Al-Fe-Si partitioning rather than source-lithology change. Immobile elements and REE patterns show pronounced LREE enrichment, HREE depletion [(La/Yb)N = 21.80–50.86], a negative Eu anomaly (Eu/Eu* = 0.47–0.93) and a positive Ce anomaly, consistent with a single basaltic protolith reworked by topography-controlled lateritisation. Benchmarked against basalt- and karst-hosted bauxite provinces, Bangam South ore falls within the compositional envelope of economically exploited metallurgical-grade bauxite, comparable to Fongo Tongo and Foumban deposits. Immobile-element and REE systematics, rather than facies morphology alone, best discriminate protolith homogeneity and weathering maturity, establishing Bangam South as a priority target for Cameroon’s aluminium sector.