Mapping depth to the crystalline basement in the Lower Benue trough (Nigeria) using power spectrum and horizontal gradient magnitude techniques on aeromagnetic data. – D . A . Obi, C . S . Okereke, E. O. Obi and A. M George
Mapping magnetic basement is an important tool in oil and gas exploration. Aeromagnetic data can define the basement over a large basin area because of the significant magnetic contrast between the crystalline basement rocks and the relatively non magnetic sedimentary cover rocks. Nine Aeromagnetic maps on a scale 1:100,000, covering the Lower Benue Trough, were digitized and processed using computer techniques, including reduction – to – the – pole, polynomial filtering and power spectrum and horizontal gradient magnitude techniques (HGM) approaches for depth estimations. The results indicate sediment thickness of less than 2.5 km and 2.5 to 5.0 km in the Afikpo and Uwet (calabar flank) sub-basins based respectively on the power spectrum and HGM approaches. However, comparison with available well information for the calabar flank indicated that the HGM – derived depth estimates were of better accuracy. In addition, the lateral extents of the sub-basins appeared to have been better outlined by the HGM- derived depth estimates.