Tag Archives: Basement Depth


The study is carried out in Otukpo area of Benue State, North central Nigeria. Geologically the area is underlain by Cretaceous sediments of the Benue Trough, mainly shales, sandstones and limestones. Aeromagnetic map of Otukpo was digitized, processed and interpreted for anomalies and causes of anomalies in the area. The airborne magnetic survey provided information about folding; the differential uplift of basement resulting from magmatic intrusions, gave rise to drape folds in the overlying sediments. Airborne anomaly indications have clearly defined large igneous bodies. These intrusive rocks of intermediate basic composition occur in the Santonian and Albian shales. Two layers of sedimentary features were observed. The average thickness for the first and second observed layers is 0.37km and 1.8km respectively. The Basement depth ranges from 3 to 8.2km. Calculated magnetic susceptibility contrast of the area was 0.073-1.71 electromagnetic units. Areas of geological interest which are exploration targets were delineated. They include areas of broad magnetic intensity anomaly closures, which are zones of structural displacement associated with deep seated basement, areas of magmatic intrusions, dyke spots, fractures and fault zones. These structural studies may yield clues to the location of concealed mineral deposits.

Keywords: Aeromagnetic Map, Basement Depth, Digitized, Magnetic Susceptibility Contrast, Processed, Sedimentary Features, Thickness and Magnetic Intensity Anomaly Closures