Geochemical Evaluation of Arimogija-Okeluse Limestones, Eastern Dahomey Basin, Southwestern Nigeria

Abstract

Abstract. 10 representative samples of limestone were collected from the Arimogija-Okeluse Axis of the Dahomey Basin and subjected to X-Ray Fluorescence analysis. Major and Trace elements were used to classify and predict the depositional environment of Arimogija-Okeluse limestone. The results for the major oxide composition revealed that CaO content ranges from 47.6-52.31% with a mean value of 50.06%. SiO 2 concentration varies from 1.94-5.24% with an average of 3.36%. Fe 2 O 3 . MgO, and Al 2 O 3 contents have mean values of 1.702%, 1.52%, and 1.09% respectively. Other oxides; Na 2 O, P 2 O 5 , K 2 O and TiO 2 are low in concentration. The Loss on Ignition also varies from 38.9-41.8 with a mean value of 40.43% suggesting a high carbonate content for the limestone. Standard Ca/Mg and Mg/Ca ratios varies from 25.87-37.63 and 0.03-0.04 with a mean of 33.31and 0.031 respectively. The high strontium content reveals a saline environmental condition of formation for the limestone. The results obtained showed that the Arimogija-Okeluse limestone is a Magnesian limestone deposited in a shallow marine environment and suitable for cement production.

Petrological and Geochemical Evaluation of the Paleocene-Eocene Lithofacies in Dahomey Embayment, Southwestern Nigeria

“…This rock is a potential hydrocarbon reservoir for the overlying shale while this character of the rock is seen in the Benin Republic sector of the basin, where petroleum is produced at marginal level [3] [13] [14]. The aspect geochemical evaluation, depositional environment and reserve estimation of limestone deposit were also reported around Orimogija and Okeluse areas of eastern Dahomey Embayment [15] [16]. However, this study focus on the distribution of diverse lithofacies, genetic description of the Ewekoro Formation with emphasis on the limestone and what characterize the environment of its deposition, the extent of diagenesis, biological influence on the chemistry of the units, major elemental composition, post depositional processes and their viability in determining its economic values.…”