Determination of Depth to Buried Magnetic Rocks under the lower sokoto basin Nigeria,Using Aeromagnetic

Abstract

Statistical spectral analysis of the residual magnetic field values in employed in this research to determine the depth to the magnetic basement rocks under the lower Sokoto Basin. The Area of the study lies between longitude 4° to 5°E and latitude 10°30´ to 11°30´N. For this analysis the study area is divided into 49 sections allowing spectral depth determination at every 15 Km by 15 Km interval of the field. The spectral analysis reveals two prominent magnetic layers. The first layer depth varies from 0.22 Km to 0.96 Km with an average value of 0.457 Km. While the second layer depth varies from 0.46 Km to 1.96 Km with an average value of 1.45 Km. The first magnetic layer is attributed to lateritic ironstone ferruginous sandstone and effect of surrounding basement rocks while the second layer is attributed to magnetic rocks intruded onto the basement surface lateral discontinuities in basement susceptibilities and inter basement features like faults and fractures. The second layer depth thus represents the depth to basement in the area and this depth has an average value of 1.44 Km. This represents the average thickness of the sedimentary formation overlaying the basement complex within the lower flange of the Sokoto Basin. The generalized depth to basement map procedure reveals that the basin in generally shallow with a maximum depth of 1.93 Km. This depth estimates reduces the possibilities of hydrocarbon accumulation. The magnetic depth estimates and the surface plot of the second layer depth reveal an irregular basement floor resulting from gently folding of the basement rock.