Integrated aeromagnetic and radiometric analysis for litho-structural and hydrothermal alteration mapping in the Mandjap I Area, Cameroon

Abstract

The present study integrates high-resolution aeromagnetic and radiometric datasets to delineate new mineral prospectivity zones within and around Mandjap I, a densely vegetated and logistically challenging tropical region located in west-central Cameroon. The study area belongs to the Nyong Complex of the northwestern Congo Craton, a geologically complex domain marked by polyphase tectono-metamorphic evolution and significant structural reworking. In such environments, conventional geological mapping is often hindered by dense forest cover and limited outcrop exposure, making airborne geophysical methods particularly valuable for regional litho-structural investigations and mineral prospectivity mapping (MPM). To enhance the structural and lithological interpretation of the area, the Centre for Exploration Targeting (CET) grid analysis was applied to the reduced-to-pole aeromagnetic dataset. The analysis identified 1,043 magnetic lineaments with lengths varying from 113.13 m to 2,880.27 m. Statistical and spatial analyses reveal a dominant ENE–WSW structural orientation, accompanied by subordinate NE–SW, NNE–SSW, and E–W trends, reflecting the influence of multiple tectonic deformation phases. Zones characterized by high lineament density and structural intersections correspond closely with the Nyong Complex known for intense tectonic deformation and metamorphic overprinting. These structurally complex domains are interpreted as favorable pathways for hydrothermal fluid circulation and mineral deposition. The integration of aeromagnetic-derived structures with radiometric signatures revealed strong spatial relationships between structural discontinuities and hydrothermal alteration zones. In particular, the K/eTh ratio proved highly effective in delineating potassium enrichment associated with hydrothermal alteration processes linked to mineralization. Fault intersections and fracture corridors systematically coincide with anomalous radiometric responses, suggesting structurally controlled hydrothermal alteration. Furthermore, the ternary radiometric composite (K, eTh, eU) enabled the refinement of the regional geological framework by discriminating previously unrecognized litho-structural units and improving lithostratigraphic interpretation across the Mandjap I region. The combined geophysical approach significantly enhanced lithological discrimination, enabling the identification and spatial delineation of granitized gneiss, embrechitic gneiss, migmatites, and high-grade metamorphic gneissic formations. In addition, eleven priority hydrothermally altered zones were identified as highly prospective targets for future exploration. These zones corroborate major structural corridors and radiometric anomalies, emphasizing the critical role of tectonic controls in ore-forming processes within the study area. Overall, the results substantially enhance the geological understanding of the Mandjap I region by providing new insights into its lithological variability, structural architecture, and hydrothermal evolution. The methodological framework developed in this study demonstrates the effectiveness of integrating aeromagnetic and radiometric datasets for MPM in highly vegetated tropical terrains and offers a robust exploration strategy for structurally complex and poorly exposed geological environments.