Application of Induced Polarization and Vertical Electrical Sounding to Locate Coal and Aquifers in Ojoma Akpa, Benue State

Abstract

The study area Ojoma is located in Akpa district of Otukpo Local Government Area of Benue State, Nigeria. The area is underlain by Awgu Shale Formation that comprises shallow marine dark Shales, carbonaceous mudstones, limestones, siltstones and sandstones. The survey applied integrated geophysical techniques such as Induced Polarization and Vertical Electrical Sounding in order to locate a speculative coal deposit and prolific aquifers. ABEM Resistivity meter (Tetrameter SAS 1000) was used for the survey and Interpred 1D Software was used for processing, interpretation of field data and modeling of the subsurface. Four survey profiles (VES 1-4) were established with traverse lines between 1000 – 1300m each. No coal deposit was discovered. However, two aquiferous zones were located at depths of 9 – 12m and 25 – 50m respectively. It is recommended that drilling of boreholes may be carried out to tap water from the second hydrogeologic zone between the depths of 25-50m. The survey result also explained the major features revealed by the survey in terms of the types of likely geological bodies and structures which gave rise to the resistivity curves and models, thereby extending geological knowledge of the area. The underlying structures which gave rise to the geological models are the existence of folded and faulted sedimentary beds in the area.