Geophysical characterisation of subsurface structures related to gold mineralisation in the Mpambaa area, SE of Iramba–Sekenke Greenstone Belt, Tanzania

Despite hosting moderate gold-grade deposits, the geophysical anomalies of the subsurface geological structures associated with potential gold deposits in the Mpambaa area in Tanzania are poorly understood. The high-resolution aero-geophysical data [magnetic, radiometric, gravity and versatile time-domain electromagnetic (VTEM)], complemented by petrophysical data in the Mpambaa area, were used to characterise the geophysical anomalies of subsurface structures associated with gold mineralisation and alteration zones. The aeromagnetic results show that the NE–SW trending dyke swarm covers the Mpambaa area. The regional and small-scale magnetic anomalies show that major and minor mineralised structures respond positively to magnetic signatures. The results from gravity data indicate that a large part of the artisanal mining area is characterised by a moderate residual Bouguer anomaly value of shallow seated subsurface structures associated with the mineralisation related to rheological contrast between intrusive complex versus metasediments through a sheared contact. The VTEM data show that the gold mineralised areas are associated with moderate to high conductive bodies. The radiometric and petrophysical results yield positive correlations on the mineralised zones, implying that the rocks have low to high radiometric concentration, moderate to high magnetisation, and moderate to high densities and are associated with conductive bodies. The gold mineralisation has been shown by Werner deconvolution to occur along lithological contacts. The integration of the findings indicates that gold mineralisation in the Mpambaa area is controlled in contacts and junctions of positive geophysical anomalies associated with hydrothermal alteration, as well as in NE–SW trending geological structures. The delineated alteration zones correlate with the known locations of gold mineralisation. This study's results are comparable to those from other similar gold mines around the globe, demonstrating the importance of aero-geophysical data as mineral exploration indicator.