Lithologic Mapping and 2D-Genelectrical Tomographic Delineation of Graphite Deposit within Kagara, part of Tegina Sheet 142, North-Central Nigeria

Abstract

Lithologic mapping, 11 geo-electrical sounding and 2D geo-electrical tomography were conducted to delineate graphite deposits in Kagara, North-Central Nigeria. The United States of America and European Union recently included Graphite among the minerals in critical global supply. Yet no attention has hitherto been given to ascertaining subsurface continuity of Kagara graphite outcrops, and their spatial extent has remained unknown. Outcrops found during the lithologic mapping are schist, amphibolite, quartzite and granite. The graphite outcrops are in sharp lateral contact with the quartzite outcrops. The geoelectrical data were acquired with ABEM Terrameter (SAS 4000). Schlumberger array was employed to conduct ID resistivity, spontaneous potential (SP) and induced polarization (IP) sounding along a traverse aligned in outcrops' strike direction in order to characterise the graphite deposits electrically. Werner Alpha array was employed to acquire 21) geoelectrical data along outcrop strike and dip directions in order to verify the ID geoelectrical characterization, and to ascertain subsurface continuation of the deposit. The 2D data were processed and interpreted using RES2DINV computer program. The geoelectrical data revealed that the graphite deposits' resistivity, IP and thickness respectively range from 2.4-93.3 fm, 2.5-120 ms, and 8.1-11.3 m. The data also revealed that graphite outurops are continuous in the subsurface along outcrops' strike and dip directions. The spatial extent of the graphite deposits was delineated within other lithologic outcrops, using the graphite outcrops spatial locations and their inferred subsurface extension. The spatial extent of the deposit was estimated to be 1470509.0 m². This and its average thickness of 10.0 m give the graphite deposit an estimated gross volume of 14705090.0 m². Employment and additional revenue would be generated by Nigerian government from the development of the deposits and other graphite deposits in the country.