Petrography and Origin of Carbonated-Hosted Rock in Okpella Edo State, South Nigeria
Abstract
This study presents an integrated petrographic and origin of carbonate-hosted rocks from okpella, Edo state. Detailed thin section examination, Depositional environment, and post-depositional modifications of the carbonate system. Carbonates were mapped and 13 samples of rocks and one water sample were prepared for analysis. Field characteristics and petrographic studies from 13 thin sections samples shows the presence of calcite, apatite, dolomite and high silicate minerals like pyroxene and olivine. 13 whole rock sample and 1 water sample made up of ten salt (CaCO3), one granite, one migmatite rock sample and one Pegmatite were analysed, using X-ray Fluorescence (X-RF),which shows presence of Major oxides, minor and trace elements like Beryllium (Be), Niobium (transition metal) (Nb),Rubidium (alkali metal) (Rb),Strontium (Sr), Barium (Ba) (Alkaline earth metals) and scandium (Sc) (REE) in abundance. Atomic Absorption Spectrometry (AAS) was used to analyse for LREEs. Which shows abundance of Lanthanum (La) 0.012-0.025ppm, Dysprosium (Dy) 0.003-0.010ppm, Cerium (Ce) 0.005-0.029ppm and Neodymium (ND) 0.003-0.029ppm including major oxides like Calcium Carbonate (CaCO3) 27.7%-35.5%, Apatite (P2O5) 13.81-29.77% and dolomite (MgO) 13.27-23.85%. The water sample shows presence of Lithium (Li) 0.014 mg/L and Fluorine (F) 0.023 Mg/L. The pegmatite sample shows presence of Silver (Ag) 2.20ppm, Gold (Au) 1.20ppm, Copper (Cu) 2.71ppm and Manganese (Mn) 4.90ppm. Tectonic discrimination plots reveal that majority of samples fall in Within Plate granite (WPG) field, Spider plot reveals REE enrichment. Different geochemical plots and field evidences, have proven that, the Carbonate deposits in okpella is of Igneous origin along share zone and has undergone multiphase tectonism and carbonaceous magmatism during the Pan African Orogeny. All these elements are of economic potentials. They are widely used in construction, cement production, metallurgy, and chemical industries.