Abstract:
Geophysical mapping of Agbaja iron deposit was carried out by integration of geophysical
methods, remote sensing and validated by geochemically analyzed borehole data of the
study area. Landsat 8 image was acquired/downloaded from the U.S. Geological Survey
site of the United States in TIFF format covering the study area. The Landsat 8 data was
pre-processed for geometric, radiometric and atmospheric correction and then UTM geo-
referenced using ARCGIS10.3 software which includes the application of pre-defined
models which reduced the effect of the earth’s rotation. The image was then enhanced to
improve the appearance of it features. Analysis such as band combination, False Color
Composite (FCC), Principal Component Analyses (PCAs) and Band ratio was applied in
mapping the iron deposit in the study area. Also, aeromagnetic data was obtained from
Nigeria Geological Survey Agency (NGSA). Aeromagnetic data processing was done
using Oasis montaj software, and the following maps were generated; Total Magnetic
Intensity (TMI), Residualization, Analytic Signal and Total Horizontal Derivative (THD).
A mineralized prospective map that shows mineralization of the study area trending NW-
SE was generated by reconciling the thematic maps using a data driven model (entropy
model). Weightage assigning was done through aforementioned model. For confirmation
of the features observed on the mineral prospective map generated, ground truthing survey
was carried out using both ground magnetic and electrical resistivity (VES). The results
from both ground magnetics and VES were qualitatively and quantitatively interpreted and
juxtaposed for comparison. The geochemically analyzed borehole data, ground magnetic
data, and VES data interpretations validated the earlier entropy produced mineralization
prospectivity map of the study area, and established that the Agbaja iron deposit in the
study area exist as a flat or almost a flat lying deposit and laterally continuous, which are
exposed in some areas and covered by lateritic top soil in other areas. It shows the depth to
the top of the iron deposit ranges from 0 m-8 m, while the thickness of the deposit ranges
from 25 -36 m and also depth to the bottom of iron deposit is 40 m at most. Hence, a
validated iron ore mineralization potential map of the study area is produced.
