Delineation of Mineral Potential zone Using High Resolution Aeromagnetic Data Over Part of Nasarawa State, North Central, Nigeria

Abstract

Qualitative analysis of aeromagnetic data of part of Nasarawa State had been carried out with the aim of delineating mineral potential zone. The study area is bounded by Longitude 8.0 E – 9.0 E and Latitude 8.0 N – 9.5 N with an estimated total area of 18,150 km2. Different filters were used to enhance the short wavelength anomalies which could give preliminary information about the magnetic minerals present in the study area. The total magnetic intensity map shows variation of both highs and lows magnetic signature ranges from 51.2 nT to 110.4 nT after the removal of IGRF value of 33,000 nT; the highs which is basement dominates the north-eastern and north-western part of the study area which corresponds to Akwanga, Wamba and Nasarawa Eggon; these are areas with promising solid minerals of economic potentials like, gold at Wamba; Tin, Columbite and Tantalite at Akwanga while Granite rocks with possible radioactive elements are in abundance at Nasarawa Eggon. The low magnetic values on the other hand, which is made up of sediment deposition also dominates the southern part of the study area, this area corresponds to Lafia, Doma and Keana; Lafia and Doma host some industrial minerals like Clay, glass Sands and the Salt Brines at Keana. The major high magnetic signature trends east-west. The greenish part of the study area indicates alluvium deposition. The filters used are vertical derivatives, downward continuation and analytic signal. The first and second vertical derivatives; shows structures like lineament that could be the host to minerals present in the study area and it trends NE-SW. The downward continued at the depth of 50 m and 100 m shows the veins where magnetic minerals most especially gold are known to settle along igneous and metamorphic rocks. The analytic signal map shows that magnetic amplitude highs could be found at the northern end with most lineaments delineated also conform to other filter used. The tilt derivative map enhances short wavelength anomalies which could be used to mapped shallow basement structures and mineral exploration targets. The results of these filters agreed largely and since most magnetic minerals are structural controls, it is expected that those lineaments identified, most especially at the northern part, could play host to those minerals aforementioned.