DELINEATING AND INTERPRETING THE GOLD (MINERALISATION) VEINS AROUND BIDA AND ZUNGERU AREA OF NIGER STATE, NIGERIA USING AEROMAGNETIC AND RADIOMETRIC DATA

Abstract

Both Airborne Magnetic and Radiometric dataset were employed to interpret the geology and geological structures that serve as host to gold and other solid minerals within the Bida (Sheet 184) and Zungeru (sheet 163). An area of 55 by 110 km square is contained within the cretaceous sediments of Bida Basin and the meta-sediments of Zungeru-Sarkin-Pawa schist belt. Data interpretation adopted concentrated on mapping geological structures, boundaries and possible gold mineralisation veins that arises from hydrothermal altered zones. Application of mathematical algorithm for data enhancing such as, Reduce-to-the-Equator and Analytical signal, to the magnetic data, Potassium (K), Thorium (Th), Uranium (U) and Ternary image of the radiometric data helps in delineating the NW-SE trending contact separating the cretaceous sedimentary formation from the meta-sediments. This trend takes off from the Southern end Bida and terminates at the Western end of Bida. The first vertical derivative and the CET analysis help in mapping the fractures, folds and contact zones. Majority of the structures delineated exist around the meta-sediments. Primarily at the Northern end of the study area are linear faults and fractures trending NE-SW around Zungeru – Yakila – Katako axis and ranges from 2 to 5 km in length within mylonite formation. Also, below Federal University of Technology Minna main campus around Minkwogi, Sunbwagi, Sabon-Dagga, Kakagi and Bobo Shiri area, are chunk of interconnected short fracture zones that exist within the magmatite. Belt type meta-sediment complexes. Results from the Analytical signal, vertical derivative, Eular Deconvolution and CET-plugin showed that most of these structures and their depth were located with in northern part and south-western region of the study area. The coordinate of these major structures and lineaments that shows degree of mineralisation were mapped on CET map most interestingly is between longitude 6˚20E to 6˚30E and latitude 9˚10N to 9˚30N. Where the meta-sediments have been intruded by medium to coarse grain biolite granite, is an evidence of structural control veins, which coincided with regions of hydrothermally, altered zones on the ternary map.