Integrated Geophysical Groundwater Prospecting using Electrical and Aeromagnetic methods in Ogobondoroko, Asa Local Government Area of Kwara State.

Abstract

This study presents one of the series of geophysical techniques, electrical resistivity to correlate the aeromagnetic anomaly in basement Complex rock terrain, around Ilorin. West Central Nigeria. An area of about 2km2 which is a suburb of Ilorin, part of Ogbondoroko, has been used as a case study for the application of electrical resistivity sounding, radial geoelectric sounding, and sounding-cum-profiling techniques in structural mapping of basement structure identified from the aeromagnetic maps of Ilorin Sheet. In this report, a demonstration of the use of electrical resistivity soundings in the evaluation of aeromagnetic anomalies of a part of Ilorin is presented. A total of twenty (20) Vertical Electric Soundings (VES) using the Schlumberger array of the geophysical electrical method were carried out. The results were presented in the form of sounding curves, tables, geo­ electric sections, anisotropy polygons, and pseudo-sections. A low resistivity E-W trend of fractures was observed at depths >35m, which is not sympathetic with the aeromagnetic lineament picked from the aeromagnetic anomaly map of the area. However, N-S fracture trends were also delineated at shallower depths. The result will serve as a guide for the application of combined geophysical exploration techniques for groundwater development options.