Integration of Aeromagnetic Interpretation and Induced Polarization Methods in Delineating Mineral Deposits and Basement Configuration Within Southern Bida Basin, North-West Nigeria

Abstract

Aeromagnetic data interpretation and induce polarization (IP) method have been integrated, analyzed and interpreted in a view of delineating magnetic minerals within some part of the Southern Bida Basin, Nigeria. Spectral analysis method was used in delineating the magnetic properties of rock which were used to determine the depth to magnetic basement, model prominent magnetic anomaly, determine the basement topography, estimate the Curie point depth isotherm, evaluate the geothermal gradient and calculate the heat flow. The Analysis of induced polarization data was used in delineating the potential fractures zones of mineralization from the pseudosections of resistivity and chargeability contour maps. Visual inspection of the magnetic anomalies and first vertical derivative maps reveal that the area is highly faulted with major faults trending East-West (E-W) and minor ones Northeast-Southwest (NE-SW) directions. The qualitative interpretation results of both resistivity and chargeability pseudosections reveal potential fractures zones trending East-West (E-W) and the depth to the anomalous body ranges from (0.3 to 2.5 km) with average overburden thickness of 2.1 km. The average resistivity and chargeability values ranges from (5.17 to 42.4 Ω m) and (1.10 to 42.3 ms) respectively. Two depth source models were interpreted using Discrete Fourier Transform method (spectral analysis) namely; the shallower sources which range from 0.45 to 1.49 km and the deeper ones which range from 1.81 to 3.24 km. The quantitative interpretation of the aeromagnetic data, depict that the average sedimentary thickness ranges from (2.3 to 3.2 km) and the average depth to the Curie isotherm in the area is 24.76 km. The results also show that the Curie temperature isotherm within the basin is not a horizontal level surface, but undulating. The regional average results for both geothermal gradient and heat flow across the study area are 23.07 °C/km and 57.66 mW m2 respectively. Based on the computed sedimentary thicknesses (2.3–3.2 km), the geothermal gradient (22.27 and 37.00 °C/km.) and the prevalent fractures, the possibility of hydrocarbon accumulation in the northern and southeastern parts of the study area is feasible, whereas other parts of the study area with low sedimentary thicknesses will favour magnetic mineral deposits such as the prevalent ooilitic iron ore deposits at Agbaja and Kotonkarifi axes. The deductions were reached after due consideration of qualitative and quantitative interpretations of both the aeromagnetic and IP data which was supported by geology of the study area.