Geochemical and Geophysical Evaluation of Structural Pathways Controlling Metallic Mineralization in the Okemesi Fold Belt, Southwestern Nigeria

Abstract

The Okemesi Fold Belt, located within the southwestern Nigerian Basement Complex, is a structurally complex Pan-African terrain with documented occurrences of gold and base-metal mineralization. However, systematic evaluation of its structural and lithological controls remains limited. This study applies an integrated geological, petrographic, geophysical, radiometric, and geochemical approach to delineate structurally controlled mineralized zones and develop a mineral systems framework. Airborne aeromagnetic and radiometric datasets from the 2009 Fugro survey were processed using reduction to the equator, regional–residual separation, analytical signal enhancement, lineament extraction, and Euler deconvolution to map lithological boundaries, faults, and shear zones. Radiometric data for K, Th, and U were analyzed to identify hydrothermal alteration and lithological variations. These datasets were integrated with 1:25,000-scale geological mapping, petrographic analysis of representative lithologies, and multi-element geochemical analyses of thirty-six rock samples, including migmatites, banded gneisses, schists, quartzites, pegmatites, and charnockites. Multivariate statistical analyses highlighted significant elemental associations and anomalous zones. Results indicate that mineralization is structurally controlled, with shear zones, faults, and lithological contacts acting as primary fluid conduits. Geophysical anomalies coincide with hydrothermal alteration zones, felsic intrusions, and pegmatitic bodies, while petrographic evidence confirms deformation-enhanced recrystallization and sulfide mineralization. This integrated study provides a robust exploration model for structurally controlled, basement-hosted mineral systems and defines priority targets for follow-up investigations in southwestern Nigeria and analogous Pan-African terranes.