ELECTRICAL RESISTIVITY AND GROUND MAGNETIC SURVEY FOR THE INVESTIGATION OF POTENTIAL MINERAL TARGETS AT AKO-MATOLE, SOUTHWESTERN, NIGERIA
Abstract
A geophysical electrical resistivity and ground magnetic survey was carried out at Ako- Matole, Ago-
Iwoye, Ogun State, Southwestern part of Nigeria. The survey area lies between the latitude
6.936342oto 6.936965oN and longitude 3.861218o to 3.862697oE. The study aimed at investigation of
the nature of the potential mineral deposits of the location using both electrical resistivity and ground
magnetic methods. Schlumberger array was employed for the electrical resistivity data acquisition
using ABEM SAS 1000 Terrameter to delineate the resistivity values and depth to the basement rocks.
The electrical resistivity technique involves the measurement of apparent resistivity distribution of
the subsurface, and from which the true resistivity values of the various earth materials can be
computed. WinResist was used for electrical resistivity data processing. Magnetic method involves
the measurement the measurement of the earth's magnetic field intensity The basic task of magnetic
methods in prospection is to differentiate subsurface according to its magnetic properties. A proton
precession magnetometer was used to acquire the magnetic data The Cartesian technique was used for
the magnetic data acquisition; Gaussian filter approach which filters the regional from residual was
applied on the field. The acquired data were subjected to Oasis montaj software. The field data
collected was qualitatively and quantitatively interpreted. The electrical resistivity results inferred
topsoil, clay and sandy clay/clayey sand with resistivity values ranging from 160.5-289.9Ùm, 34.4-
69.6Ùm, and 146.6-437.5Ùm respectively with total depth to basement rocks ranging from 11.9m and
19,2m.TheTotal Magnetic Intensity (TMI) value of the area ranges between 32856.2 to 33323.2 nT
while the residual magnetic values were in the range of about -4.3 and 1.7 nT. The interpretations
of the magnetic maps, it reveals the presence of magnetic anomaly at some parts of the study area
which indicates the presence of potential magnetic mineral which can be very useful for exploration.
This is trending at the Northeastern - Southeastern (NE – SE) part of the study area, the Southwestern
(SW) part of the study area possesses the lowest magnetic intensity; this implies that more mineral target
is available in the Eastern region. The subsurface geological structural traps for mineralized
localization include the presence of shallowly buried magnetic sources at the eastern part inferred as
granite gneisses.
