Quantitative discovery and geophysical estimation of limestone deposits at Takowangwa area, Mokwa, North-Central Nigeria

Abstract

Takowangwa area in Mokwa, Niger State, North-Central Nigeria was probed using Electrical Resistivity (ER) and Induced Potential (IP) methods to discover possible limestone deposits. The probe was conducted at five profiles, within which 25 Vertical Electrical Soundings (VES) were carried out. The Terrameter SAS 4000 for which the maximum current electrode spacing AB/2 was 100 m and the Schlumberger array were adopted for the soundings. The results from the computer modelling software (IP2WIN) revealed the occurrence of limestone deposits in all the five probed profile locations. This was inferred from the exhibited low resistivity and chargeability values which characterised all the profiles in their first and second geoelectric layers. The characterised low resistivity and chargeability values ranged respectively from 43 to 155 Ωm and 1.12 to 155 msec, while the thickness range was from 20.69 to 86.53 m. These two geophysical approaches (Electrical Resistivity and Induced Polarization) showed a good degree of correlation in the resistivity and chargeability values of the limestone and their varying quantities. This research work estimated the occurrence of vast limestone deposits of the magnitude 2.0 x 106 t which can be of very much economic importance in domestic, mining and industrial purposes. More detailed integrated geological, geophysical studies and drillholes to cover the study area and even with further extension beyond the probed area for better understanding of the economic potential of the study area were recommended.