Inorganic Geochemical Evaluation of Maastrichtian Coal at Gombe, Gongola Basin, Nigeria: Implications for Resource Potential and Paleoenvironments

Abstract

The Benue Trough has been known to have great potential for resources such as coal, hydrocarbon, limestone, barite, gypsum, etc. The study area is Maiganga coal mine located at Gombe, Gongola Basin, northern Benue Trough in northeast Nigeria. Two coal seams, shales, siltstones, sandstones, and intercalation of ironstones make up the stratigraphic succession of 35 m thick. The coal is currently being exploited as a source of fuel at the Ashaka Cement Factory, Ashaka, Gombe state. Elemental and proximate analyses of the coal samples were carried out to investigate coking potential, acid generation potential and its suitability as a source of fuel. The paleodepositional condition and the original plant that form the coal were also examined. The proximate analysis showed that the moisture content ranges from 9.55% - 11.13%, volatile matter (40.88% - 44.89% dry), ash (5.29% - 13.99% dry), fixed carbon (41.30% - 53.41% dry) and calorific value (5469 - 6452 kcal/kg). Average values of the major elements; K2O, MgO and Fe2O3 are low but a high loss on ignition was obtained for the coal ash. The samples recorded low concentrations in the trace elements, except for Ni, Cu, Ba, Sr, and Zr. Coal seam A exhibits negative europium anomaly and positive cerium anomaly indicating peat vegetation (Sphagnum L.) while coal Seam B showed negative cerium anomaly indicating soil grown plants (Mangrove and Vicia villossa). The present investigation showed that the coals were deposited in fluvial to paralic environments. The coals are not suitable for coking but have potential as a source of fuel and power generation.