Interpretation of spectral depth and upward continuation analysis of sub-surface structures in parts of Borno Basin, Northeastern Nigeria, using aeromagnetic data

Aeromagnetic data of part of chad basin, Northwestern Nigeria, has been analyzed for the purpose of investigating the sedimentary thickness beneath the surface. The study area was covered by 4 aeromagnetic maps. The aeromagnetic maps were digitalized on a 3km grid and later compiled to produce a combine aeromagnetic data file for the area. The data file comprises 1369 data points, polynomial fittings method was applied in the regional residual separation. The residual map was later sub-divided into 16 spectral sectors. The result of the study shows that the first layer depth was estimated to have a range of 0.18km to about 1.9km while the second layer depth was estimated to have range from 2.9km to about 4.2km. The highest sedimentary thickness of 4.2km occurred at the extreme northeast part of the study area and corresponds to areas around Golgoram. Further analysis involving the application of upward continuation filters were performed to improve the quality of the magnetic data for better understanding of the subsurface geology within the study area