Analysis of high-resolution aeromagnetic data of geological transition zones of the southeastern part of Bauchi, NE Nigeria

Abstract

The study investigated the subsurface tectonic framework and structural disposition of the 
basement/sedimentary transition zone in the southeastern part of Bauchi, Northeastern 
Nigeria, to delineate the basal and lateral contacts and unravel some of the hydrogeolog
ical and engineering challenges in such areas. The method deployed involved the analysis 
of high-resolution aeromagnetic data, through the application of several filtering tech
niques. The transformation techniques applied include reduction to pole, second vertical 
derivative techniques using analytical signal, and Euler deconvolution. The Euler depth 
result range of 1–200 m coincides with the region where basement rocks outcrop on the 
surface, while the depth range between 0 and −800 m corresponds to the sedimentary 
terrain (the Kerri-Kerri formation) or part of the area where the basement rocks are over
lain by thick overburden sediments. The 2-D depth model around the transition zone 
showed high variability as it ranged from 0 to −500 m owing to the presence of basement 
highs and depressions. The basement highs are usually characterized by impermeable 
rocks with poor aquifer characteristics and are responsible for the failure of boreholes in 
these zones. The basement depressions, however, constitute good groundwater prospects 
depending on the hydrological properties of the sedimentary infill. The general orienta
tion of lineaments in the area revealed NW–SE, NE–SW, and ENE–WSW, with minor N–S 
and E–W trends, suggesting a pan-African origin. The occurrence of lineaments in parts 
of the contact zones also contributes to the groundwater prospects. The erratic bedrock 
relief exhibited by the study area is also detrimental to the foundation of pavement struc
tures as it undermines their durability. Therefore, a detailed site investigation is crucial 
in such geological contact zones prior to the erection of structures. Additionally, vertical 
electrical soundings are recommended before borehole drilling to ascertain the suitability 
of these hydrogeological complex zones.