Application of Geophysical and Remote Sensing Techniques to Delineate Lateritic Bauxite Deposit Zone in Orin Ekiti, Nigeria

Application of geophysical and remote sensing techniques was used to delineate lateritic bauxite zone in Orin Ekiti, Southwestern Nigeria. Three basic methods were employed to qualitatively define and identify plausible areas or zones of bauxite ore deposit within the study area. The remote sensing data utilized for the study were the Landsat (ETM) image and Shuttle Radar Topography Mission (SRTM) data in Digital Elevation Model (DEM) image. From the processed remote sensing data, features like topography, vegetation, settlements, and rocks which are all favourable features for bauxite formation were all observed and delineated. The use of magnetic method through the use of high resolution aeromagnetic data (HRAD) of sheet 224, enables different enhancement magnetic maps to be generated. These maps were used to define boundaries, contacts and edges of different rock types within the study area, and the production of a mineralization potential map for the study area. Three major rock types were identified and mapped, these are magmatite, granite gneiss and charnockite rocks. Charnockite rocks which are considered as parent rock for bauxite have low magnetic susceptibility values; therefore, zones of low magnetic susceptibility are mapped, with values ranged between -92.4 nT to -56.9nT, observed at central part trending in the east to west, and also in the northwestern and southwestern parts of the study area. Five traverses were established for electrical resistivity imaging (ERI). Bauxite being a weathered product of charnockite rock, zones of its existence is expected to have high resistivity values. So, along the five traverses, zones of high resistivity values were mapped as bauxite zones, having value ranged between 600 Ωm to 101404Ωm, and occurred within the depth ranged between 0 (surface) to maximum depth probed (15m). All the techniques adopted in the investigation showed the bauxite deposits within the study area are surficial or near-surface occurrence.