Electrical and electromagnetic geophysical signature associated with geological frame of polymineralic deposit within hydrothermal alteration zones

Mineral exploration involves the acquisition of economic extractive mineral deposits, in which the relevance of geophysical methods cannot be overemphasized for its fast, cost effective and non-destructive ways of understanding the subsurface conditions. In this work, signature reference from electromagnetic, electrical resistivity, and induced polarization geophysical methods assisted in unraveling the presence of a polymineralic deposit, as well as determining the economic potential of the deposit within investigated hydrothermally altered zones in Ilesha Schist Belt, Southwestern Nigeria,. The electromagnetic method delineated anomalies related to mineralized zones of weathering, fracturing, and dyke-like structures. Electrical resistivity (ER) and induced polarization (IP) methods highlighted areas with fractures/faults, mineralized weathered layer, and disseminated sulfide deposits between the depth of 5 and 60 m. Resistivity and chargeability variations (33.8–529 Ωm and 3.88–12.2 msec respectively) of the mineralized structures and formations assisted in delineating probable presence of galena, pyrite and chalcopyrite sulfide ores. A validation study using borehole data revealed mineralized host rock at the depth of 25.3 m, with the presence of disseminated metallic sulfide in quartz veins within the depth of 27.8 to 40.8 m. Similarly, validation studies using geochemical analysis shows pathfinder elements of sulfide minerals; iron (Fe), sulphur (S), copper (Cu), lead (Pb), and antimony (Sb); confirming the presence of galena, pyrite, and chalcopyrite deposits. Both validation methods confirmed the reliability of geophysical signature in identifying polymineralic deposits within the investigated area. This research has however revealed more areas, identified as exploitable polymineralic deposits, to enhance mining operations in the study area. •Investigation of polymineralic deposits was done using geophysical signatures.•Mineralized zones were delineated within fractures, and dyke-like structures.•These mineralized zones occurred at shallow depth between the depth of 5 and 60 m.•Borehole and geochemical data confirmed the presence of the mineralized zones.