Spectral depth analysis of upper Benue Trough and Borno Basin, northeast Nigeria using aeromagnetic data

Abstract

Spectral depth analysis of aeromagnetic data covering latitude 9.50 – 12.00 and longitude 9.50 – 12.00, which corresponds to parts of upper Benue Trough and southern Borno Basin, northeast, Nigeria, was carried out for the purpose of investigating the sedimentary thickness beneath the subsurface. The study area was covered by 25 aeromagnetic maps. The aeromagnetic maps were digitized on a 3 km by 3 km grid and later compiled to produce a combined aeromagnetic data file for the area. The 3 km spacing interval imposed a Nyquist frequency of 0.167 km-1 while the data file comprised 7921 data points. The polynomial fitting method was applied in the regional–residual separation. The residual map was later sub-divided into 41 spectral sections. The result of the study shows that the first layer depth was estimated to have ranged from 0.268 km to about 1.08 km while the second layer depth was estimated to have ranged from 2.06 km to about 3.35 km. The highest sedimentary thickness of 3.35 km was found at the northern part of the area and corresponds to areas around Damaturu and Bulkachuwa. These areas may be subjected for further geophysical method like seismic reflection/refraction, so as to ascertain its hydrocarbon potential.