Subsurface and lithological evidences from aeromagnetic data in some parts of the Sokoto Basin, North West Nigeria

Abstract

In this work, a reconnaissance study is presented to delineate the subsurface and lithological interpretation of the aeromagnetic data. To achieve this goal, several enhancement techniques and filtering processes were carried out on these maps. At first, the total intensity aeromagnetic map is processed through the application of reduction to the magnetic equator technique. Six aeromagnetic data sheets covering some parts of the Sokoto Basin were used. These maps were digitized on a TMI grid. An analysis of the total magnetic field over the area of study was carried out using the aeromagnetic data sets. The following deduction were made: the interpreted lineaments follow a predominantly EW- and NSW-trending orientation, while other orientations in the survey area include NW-, ENE- and, more rarely E-trending structures, the existence of several high short wavelength magnetic closures with steep gradients near the geologic boundary is a strong indication that the basin may not be as large as shown by the geologic map. The residual magnetic field values were employed to obtain the two-dimensional Fourier transforms from which the radial spectrum was extracted. The slopes of the graph of spectral energy against frequency of nine sections were obtained and used to estimate the depth values. The results suggested that the deeper depth of the study area ranges from 1.99 km – 2.83 km while the shallow depth ranges from 0.78 km – 1.25 km in conformity to the delineation of favourable lithological units between cretaceous meta-sediments and Eocene boundary. Finally, the study reveals that structural interpretation based on aeromagnetic data is an efficient tool for frontier exploration for hydrocarbon accumulation and/or other mineralization.