INTEGRATION OF GEOPHYSICAL, GEOCHEMICAL AND GEOTECHNICAL PROSPECTING METHODS TO PROSPECT FOR BENTONITE IN AFUZE, SOUTHWESTERN NIGERIA

Abstract

An integration of geophysical , geochemical and geotechnical data sets has been carried out in order to prospect for bentonite (a clay mineral) in Afuze, Edo-State. The research methodology involved establishing 10 traverses east to west direction, 20 m away from the Afuze-Auchi road, conducting a geophysical survey (electrical resistivity imaging technique ) using the dipole-dipole array with interval spacing of electrodes 5 m and inter-traverse spacing of 10 m, collection of samples from areas with resistivity signatures corresponding to target mineral (bentonite), conducting a geochemical analysis using x-ray florescence test to determine elemental distribution of sample, digestion and titration to determine sodium, calcium percentage present in sample and to conduct a geotechnical analysis to with reference to Liquid limit in order to identify the clay mineral (bentonite). Bentonite was identified in traverses 1, 5 and 6, with range of resistivity values ranging from 10-100Ω. Bentonite present in Afuze was discovered to be of calcium type due to the percentage of calcium. Result from digestion and titration test showed sample obtained from Traverse 1 had higher calcium percentage 158 parts per million (ppm) and had a sodium percentage of 48 ppm . Traverses 5 and 6 had calcium percentage of 93 ppm and a sodium percentage of 41 ppm. Results from the x-ray florescense test showed sample obtained from traverse 1 had Aluminium (Al) content of 20.770 ppm, silicon content of 27.6314 ppm and calcium content with 0.1353 ppm. Sample obtained from traverse 5 and 6 had Aluminium (Al) content of 15.0876 ppm, silicon content of 37.5238 ppm and calcium content with 0.0878 ppm. Sample obtained from traverse 1 had a liquid limit of 176 and sampled obtained from traverses 5 and 6 had liquid limit of 177. This data set has been able to provide more details on bentonite having sedimentary origin and detailed information concerning bentonite occuring in Nigeria, serving as a guide for future researchers.