Geochemistry of stream sediments from Eseka area (SW Cameroon): implications for surface process assessment and precious metals (Au, Pd, and Pt) exploration

Stream sediment geochemical data from SW Cameroon were examined as a contribution for surface process study and preliminary exploration of Au, Pd, and Pt. Samples were collected from both active and overbank stream sediments. Samples were analyzed for mineralogy, major and trace elements including rare-earth elements, and Au, Pd, and Pt concentrations. The sediments are mainly made up of quartz, gibbsite, goethite, and kaolinite. Their chemical composition is dominated by SiO2, Al2O3, and Fe2O3. They are geochemically classified as Fe-sand and derive from moderate to intense weathered sources which are the local surrounding rocks. Variability in the chemical composition could be attributed to weathering and hydrodynamic sorting of sediments during transport. Trace and rare-earth elements are sparsely present in river sediments in the Eseka area. The high Zr contents could reveal high proportion of zircon as a resistant mineral to weathering. The normalized REE patterns show relative HREE enrichment due to the fact that zircon preferentially incorporates HREE. The variable La/Sc, La/Co, Th/Sc, Zr/Cr, LREE/HREE ratios, and Eu-anomalies suggest that the stream sediments may have originated from mixed felsic and mafic source contributions. Gold, Pd, and Pt have variable contents with the highest contents in the active stream samples. The active stream sediments are the appropriate tools for geochemical Au surveys in humid forest regions. Despite the low contents in stream sediments, some sampling points are favorable for further Au, Pd, and Pt exploration in their upstream sources. The clayey materials should be favorable for Pd and Pt accumulations.