Geological and Geo-electrical Outlining of Graphite Deposits Within Kagara, North-Central Nigeria

Abstract

The specific locations of graphite exposures in Kagara, their host rocks, as well as their spatial extent and gross volume have hitherto remained unaddressed. This study focused on spatially outlining the deposits and conservatively ascertaining their gross volume, using combined surface geological mapping and geoelectrical surveying techniques. The geoelectrical surveying aspect comprised 1D geoelectrical (electrical resistivity, spontaneous potential, induced polarization) sounding, and 2D geoelectrical (electrical resistivity and induced polarization) tomographic surveying conducted using ABEM Terrameter (SAS 4000). The 1D electrical resistivity data were processed and interpreted using WinResist version1.0 resistivity inversion software. The 2D geoelectrical tomographic data were processed and interpreted using RES2DINV computer program. The rock outcrops found are quartzose - micaceous as well as graphitic schists, amphibolite, quartzite, coarse grained biotite granite, and exposures of graphite bodies. The graphite bodies are hosted within the schist and quartzite. The schist, amphibolite and quartzite rock bodies appear to be lateral metasediment equivalents, and therefore are synchronous. The geoelectrical attributes of the graphite bodies are 2-90 Ωm resistivity value, combined with 1-20 ms induced polarisation and negative spontaneous potential values. The deposits exist within 0.7 – 12 m depth interval, occupy 1470509.0 m2 surface area, and constitute 14705090.0 m3 conservative gross volume. The graphite deposits appear to be sheet like bodies interlaid with the quartzite and schist bodies.