Application of Electrical Resistivity Tomography in Mapping the Lateral Extent of Ohia Kaolin Deposit in Umuahia Southeastern Nigeria

The Electrical Resistivity Tomography of Ohia community in Umuahia for eight (8) profiles located within the coordinates and using Integrated Geophysical Instrument (IGI) for kaolin mapping was carried out. The resistivities obtained from the readings were converted to apparent resistivities and plotted using the RESINVx64 software to infer the electrical responses of the subsurface at the injection of Direct Current (D.C.) through the current electrode of a higher potential. Wenner configuration that is characterized by equidistance between the potential-potential electrodes and the potential-current electrodes was deployed in view of the expected outcome which is the lateral extent of Kaolin deposit. Resistivity inversion of three iterations mapped the subsurface for its electrical responses. Different profiles have different kaolin signatures though with some similarities in some cases. ERT 1 and ERT 3 being deeply buried are close in terms of prospect similarities while ERT 3, ERT 4 and ERT 5 have some similarities in their prospect distributions as deposits become dense southwest ward though discontinuous. ERT 6 and ERT 7 follow similar depositional trend with massive overburden being deeply buried except that the latter has kaolin blended with other rocks. Accessibility to the prospect in ERT 8 would attract less investment because of its closeness to the surface. The lateral spread of kaolin is between 7.5 and 97.5 m with a depth of burial ranging from 1.25 to 9.26m.