Utilising the 3D mineral system approach to identify the source of alluvial gold deposits in Ibala Town, Southwest Nigeria: an In-depth geological and geophysical exploration

The Ibala gold field, discovered by artisanal miners in 2018, is located east of Ibala town in Osun State, southwest Nigeria. As older mines are depleted and abandoned, miners are now investigating the source of the deposits, believed to be auriferous quartz veins. This study uses the mineral system approach to trace the origin of the alluvial gold in the Ibala area. The research is conducted in three phases: first, a detailed analysis of the region’s structural patterns and rock distribution is undertaken to understand the area’s tectonic history. Next, a 3D conceptual model is created using an integrated geological and geophysical modeeling techinque to identify exploration targets and map the mineral system components. Finally, on-site verification is performed to validate the findings. The study reveals that the gold originates from auriferous shear zones characterized by high conductivity and chargeability geophysical signatures. These zones were formed by auriferous fluids released during the metamorphic devolatilization of deep volcanic rocks. As the fluids migrated through shear zones, they interacted with host rocks, precipitating gold alongside pyrite. When weathered, the gold-bearing material is transported via drainage channels, which miners now exploit. By using a mineral system approach, this research pinpoints the primary gold sources, supporting more efficient resource management and sustainable mining practices in the region.