32. 3-DIMENSIONAL (3D) ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) GEOPHYSICAL INVESTIGATION OF MINERAL OCCURRENCES IN USEN, SOUTHERN NIGERIA by Enoma N., Ogah V. A. and Wilkie S.O. Volume 51 (May, 2019 Issue)
3-DIMENSIONAL (3D) ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT)
GEOPHYSICAL INVESTIGATION OF MINERAL OCCURRENCES IN USEN, SOUTHERN
NIGERIA
Enoma N., 2Ogah V. A. and 1Wilkie S.O.
Mineral Resources Engineering Department, Edo State Polytechnic Usen, Edo State.
Soma Engineering Limited, Benin City, Edo State.
Abstract
Electrical Resistivity Tomography (ERT) investigation was carried out at two (2)
locations at Usen Ovia south west area of Edo State, Southern Nigeria. This was done
with a view to target deposited minerals in the survey locations. The survey was done at
two different locations
Elawure Grammar School field environment and Old Quarry environment, located
within longitudes East and latitude North. A series of 2D
apparent resistivity data were acquired in parallel and perpendicular directions using
Dipole-dipole electrode configuration with resistivity meter SAS 1000 using electrode
separations of a = 5m and inter spacing of L=10m making a total of 60m square grid
for the lateral extent. The 2D data set were inverted separately using RES2DINV
software producing 2D models of each line. Then the 2D data were collated into 3D
data using the inversion code RES3DINV. The images were presented as 3D slices and
block models. The total depth attained for the two locations were 15.7m (51.81ft). The
material and aggregate that fall within the resistivity range (17.8 Ωm to 46938 Ωm)
observed from the models are dolomite, maris, clay, alluvium, moraine, soil 40% clay,
soil 20% clay, lateritic soil, sand clay/ clay sand, limonite, quartz, rock salt, lignite,
syenite, basalt, schists, marble, conglomerates, and sandstone.
The physical properties of lateritic soil, sand, sandstone, shale, clay and dolomite agree
with some of the outcrop minerals found in the study area. This research has
acknowledged the fact that the minerals that can be found in Usen are clay, sand,
laterite, sand clay, sandstone, and dolomite.
Keywords: Tomography, resistvity, aggregate, minerals, configuration.