Application of Drone-Borne Magnetic Surveys for Mapping Shallow Mineral Targets in North West Nigeria

This study evaluates the application of unmanned aerial vehicle-borne magnetic surveys for high-resolution mapping of shallow mineral exploration targets in North West Nigeria, comparing the performance of drone magnetics with conventional ground and helicopter-borne alternatives. UAV-borne magnetic surveying has emerged as a cost-effective methodology for bridging the resolution gap between ground surveys and conventional helicopter or fixed-wing AEM surveys, offering flight heights of 10 to 30 metres above terrain and line spacings of 5 to 25 metres that produce unprecedented shallow target resolution. This study designs and executes drone magnetic surveys over three mineral exploration test areas in Kebbi, Zamfara, and Sokoto States, targeting gold-bearing quartz vein systems and iron formation outcrops at shallow depths. A DJI Matrice 600 Pro drone carries a fluxgate magnetometer with full compensation system for platform noise. Surveys are flown at 15 metres terrain clearance with 10-metre line spacing at 5 metres per second. Ground truth is provided by co-located ground magnetic surveys and geological sampling. Findings reveal that drone magnetic data resolves features as small as 8 metres at 15 metres flight height, compared to 50 metres for equivalent helicopter AEM data. The signal-to-noise ratio for magnetic anomalies of less than 100 nanotesla amplitude is significantly better in drone surveys than in ground surveys in rugged terrain, where terrain clearance corrections degrade ground data quality. Three new drill targets are identified from drone magnetics that were not apparent in the NGSA aeromagnetic data. The study recommends drone magnetics as the optimal shallow mineralisation survey tool in North West Nigeria's challenging terrain.

Keywords: drone magnetics, UAV survey, shallow minerals, North West Nigeria, high-resolution mapping.