Preliminary assessment for delineation of mineralized structures and potential gold alteration zones in Igarra Schist Belt southwestern Nigerian Basement Complex

Abstract

This study presents an integrated interpretation of high-resolution aeromagnetic data for the delineation of mineralized structures and prospective gold mineralisation zones in the Auchi area of the southwestern Nigerian Basement Complex. Total Magnetic Intensity (TMI), Reduction to the Equator (RTE), First and Second Vertical Derivatives (FVD and SVD) and Analytic Signal Amplitude (ASA) were used in the study to enhance magnetic anomalies and delineate lithological contacts, structural discontinuities and mineralization controls. The results show different regional and residual magnetic domains with prevailing NE-SW basement fabrics and ENE-WSW to WNW-ESE structural corridors related to Pan-African tectonic deformation. High analytic signal anomalies are related to lithological contacts, major faults, shear zones and intrusive contacts indicative of favourable pathways for hydrothermal fluid migration and structurally controlled mineralization. Derivative maps further delineated shallow faults, fractures and contacts defining prospective mineralization corridors. Validation with existing artisanal gold mining sites shows a strong spatial relationship between known mineral occurrences and high magnetic anomalies, confirming the effectiveness of the integrated geophysical approach. Areas around Ojirami, Akuku, Somorika, Ogbe and the north-eastern part of the study area are considered as priority exploration targets, due to the convergence of favourable lithology, structural complexity and magnetic signatures. The study revealed that integrated aeromagnetic interpretation provides an effective and cost efficient platform for regional mineral exploration and provides a reliable framework for subsequent integration with aeroradiometric, gravity, remote sensing and geochemical datasets to enhance mineral prospectivity evaluation within the Nigerian Basement Complex.