Integrated bedrock and stream sediment geochemistry with multivariate analysis for mineral exploration in the Okemesi–Ijero Basement Complex, southwestern Nigeria

Abstract Integrated geological mapping, bedrock and stream sediment geochemistry, and multivariate statistical analysis were applied to evaluate the mineralization potential of the Okemesi–Ijero area within the Precambrian Basement Complex of southwestern Nigeria. Detailed field mapping identified a polydeformed assemblage comprising quartzites of the Effon Psammite Formation, schists, migmatite–gneiss complexes, granitoids, pegmatites, calc-gneiss, and charnockites, reflecting a complex tectono-magmatic history. A total of 85 bedrock samples and 70 stream sediment samples were collected and analyzed for major and trace elements using inductively coupled plasma techniques following four-acid digestion and lithium borate fusion. Geochemical results show marked spatial variation in elemental concentrations across different lithologies and drainage systems. Granitic and pegmatitic rocks are enriched in lithophile and rare-metal-related elements, whereas polymetallic associations involving Cu, Pb, Zn, Mn, and Sn characterize granitoid and structurally disturbed zones. Stream sediment geochemistry effectively integrates upstream bedrock signatures, highlighting drainages influenced by granitic and pegmatitic sources and areas of elevated base-metal concentrations. Multivariate statistical analyses, including factor analysis, principal component analysis, and hierarchical cluster analysis, successfully discriminate background geochemical signatures from anomalous elemental populations and elucidate elemental associations related to lithology, magmatism, and secondary dispersion processes. The combined geological, geochemical, and statistical evidence indicates that the Okemesi–Ijero area is prospective for base-metal and rare-metal mineralization, particularly within granitic and pegmatitic domains and structurally favorable zones. This study demonstrates the effectiveness of integrating multivariate statistical techniques with conventional geological and geochemical methods for mineral exploration in complex basement terrains and provides a transferable framework for regional exploration targeting.