Ashaka Quarry: A Prolific Zone for Petroleum Geochemical Exploration and Palaeoenvironmental Interpretation. A Case Study of Kanawa Member of Pindiga Formation, Gongola Basin, NE Nigeria

Abstract

Detailed geological mapping and sample collection at Ashaka Quarry has been carried out with the aim of conducting geochemical investigation on shale so as to determine their source generative potential and depositional environment.  Forty (40) shale samples of the Kanawa Member from the Gongola Basin were used for petroleum geochemical analysis using AAS and MP- AES to determine source rock maturation level of samples collected for their trace element concentrations that have been incorporated into the petroleum charge system. The overall results showed that Fe and V elements have the highest concentration value which corresponds to global practice, while other elements such as Zn, Ni, Cr, Co, Mn, Pb, and Cu have appreciable concentrations that have indicated maturity. The higher elemental values might be indications that oil/gas supposedly generated most have been expelled into the reservoir system. V/Cr ratio was used to determine the environment of deposition of the shales, and as such, majority of the samples were deposited under euxinic/suboxic environment, while only 1 sample was deposited under anoxic condition. Therefore, this study showed that the shales of the Ashaka Quarry have indicated maturity levels for the generation of oil/gas.