Induced Polarisation Survey for Sulphide Mineralisation in Ebonyi State

This study employs the induced polarisation method to detect and delineate sulphide mineralisation in the lead-zinc belt of Ebonyi State, South East Nigeria. Ebonyi State hosts significant lead-zinc occurrences in the Abakaliki fold belt, associated with hydrothermal vein systems and disseminated sulphide mineralisation. The IP method is particularly sensitive to metallic sulphide minerals through their chargeability response, making it a standard technique for base metal exploration. This study acquires time-domain IP data along eight profiles totalling 9.6 kilometres in Ikwo and Ezza North local government areas, using the Schlumberger array with current electrodes at AB spacings of 200 to 600 metres and a primary current of 2 amperes. Both apparent resistivity and apparent chargeability pseudosections are constructed and inverted using RES2DINV. Geological mapping and rock chip sampling accompany the survey to validate geophysical interpretations. Findings reveal chargeability anomalies in the range of 18 to 42 milliseconds peaking at depths of 20 to 65 metres along three profiles, spatially associated with known galena-sphalerite outcrops mapped in the geological reconnaissance. The chargeability highs are spatially coincident with resistivity lows that indicate conductive sulphide masses embedded in resistive limestones. Geochemical sampling from surface exposures confirms elevated lead, zinc, and silver concentrations in the anomalous zones. The study identifies three IP targets warranting further diamond drilling investigation and demonstrates the effectiveness of combined IP-resistivity surveying for sulphide exploration in the Abakaliki fold belt.

Keywords: induced polarisation, sulphide mineralisation, lead-zinc, Ebonyi State, chargeability.