Frequency-Domain Airborne Electromagnetic Survey Reprocessing for Mineral Exploration in Kaduna State

This study reprocesses and reinterprets legacy frequency-domain airborne electromagnetic data to improve mineral exploration targeting in Kaduna State, North West Nigeria. Kaduna State hosts diverse basement complex mineral resources including gold, precious stones, iron ore, and industrial minerals. Historical FAEM data acquired in the 1970s have not been adequately exploited with modern processing and inversion techniques, representing an underutilised national geoscience data asset. This study reprocesses FAEM data for the Birnin Gwari and Kafanchan map sheets from the NGSA legacy data archive. Modern processing steps applied include levelling, IGRF correction, and system response deconvolution. Conductivity-depth transform is applied to generate apparent conductivity depth slices. The processed data are compared with updated geological mapping to produce interpreted conductor maps. Coincidence with updated NGSA geological maps identifies the geological context of electromagnetic anomalies. Findings reveal a northeast-trending conductive zone of 2 to 8 ohm-metre conductivity at depths of 20 to 80 metres in the Birnin Gwari area, spatially coincident with a known gold-bearing mylonite zone in the geological literature. Secondary conductors of smaller amplitude and extent are associated with graphite schist units that are geochemically anomalous in gold and arsenic from NGSA stream sediment sampling. The study demonstrates that modernised reprocessing of legacy FAEM data can generate new mineral exploration leads at zero data acquisition cost and recommends systematic archival reprocessing across all NGSA legacy AEM datasets.

Keywords: airborne electromagnetic, reprocessing, mineral exploration, Kaduna State, conductivity-depth.