GEOPHYSICAL INVESTIGATION OF PART OF THE FEDERAL UNIVERSITY OF TECHNOLOGY, AKURE, NIGERIA

Abstract

Geophysical studies have been undertaken at the undeveloped southwestern flank of the Federal University of Technology Akure. The area is underlain by the Precambrian Crystalline Basement complex rocks. Six traverses were established in approximately W-E and N-S directions with lengths varying from 440 to 600 m. The methods adopted are the ground magnetic, electromagnetic (VLF-EM) and electrical resistivity using dipole-dipole profiling and Vertical Electrical Sounding (VES) technique. The acquired field data’s were processed using 2D Euler Deconvolution, Karous Hjelt, Diprowin and WinRESIST respectively. Geologic structures were delineated from sections generated from the methods adopted. The integrated results of the, magnetic, EM-VLF and electrical resistivity using dipole-dipole profiling guided the choice of thirty five (35) VES stations occupied within the study area. The VES results delineated three geoelectric layers overlying the resistive basement, comprising the topsoil, weathered layer and partially weathered/fractured basement. The depth to the top of the basement (overburden thickness) varies from 3.2 to 69.2 m. On the basis of the combination of the results of geomagnetic depth column, VLF-EM 2-D model, 2-D resistivity structures and geoelectric sections along the six traverses, some features presumed favorable to ground water accumulation were identified. Traverses 1 and 2 show existence of probable geologic features between station 180 and 300 m, suspected to be fractures that may facilitate location of groundwater abstraction facilities. Results obtained along traverses 3 and 4 depict some conspicuous anomalies on the southern flank at station 40, 160, and 300 m. Some level of correlation exist among the subsurface models depicted by the geophysical methods along traverses 5 and 6. The features identified at station 160 and 350 m west of traverse 5 were delineated on traverse 6 between station 130 and 400 m thus, indicating the presence of fractures, fluid saturation media and other hydrogeological related features. Therefore, the hydrogeological settings within the study area present fairly favorable characteristics.