Petrography, geochemistry and industrial quality of the Etono limestone in Ugep Southwest, Southeastern Nigeria

Abstract

Petrographic and geochemical analyses were carried out on limestones occurring in Etono, Southwest Ugep, Southeastern Nigeria to determine their chemical composition, industrial uses and classification. Samples of limestone in the area were subjected to petrographic study and analyzed geochemically using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and X-Ray Fluorescence (XRF) techniques. The petrographic analysis reveals that the Etono limestone contains high percentage of carbonate materials with scanty organic remains and patches of iron. The bulk- rock composition of the limestone shows that the average SiO₂ = 9.02%, Al₂O₃ = 1.95%, Fe₂O₃ = 2.08%, MgO = 0.39%, K₂O = 0.47%, Na₂O = 0.00%, CaO = 47.92%, SO₂ = 0.24% and LOl = 37.37%. The limestone is classified based on their moderately high CaO, SiO₂ and LOl and very low MgO. The mean CaO (47.92%) of Etono Limestone is high relative to the mean CaO of Agoi Ibami Limestone (43.83%) but low relative to the Mfamosing Limestone (55.30%) and the mean SiO2 values of 9.02% is high relative to Mfamosing Limestone (0.38%) but low relative to Agoi Ibami Limestone (13.93%). Results of the geochemical investigation reveal a shallow marine environment of deposition (EOD) for Etono Limestone. The higher values of CaO and LOl and lower values of SiO2 of the limestone suggest that it can be used for cement production, building stone, filler and agricultural purposes.