Geochemical Composition And Textural Features Of Some Carbonate Rocks In Parts Of South Western Nigeria

Abstract

This study was carried out on limestone representing the Ewekoro formation of the Dahomey basin as exposed in Sagamu and Ewekoro quarries of West African Portland Cement Company and Ibeshe limestone quarry of Dangote Cement Company. The study involved the determination of the major oxides of the limestone deposit using ultraviolet spectrophotometer as well as the determination of the depositional and biogenic features of the limestones petrographically. The major oxides analyzed for are CaO, MgO, Al2O3, SiO2 and Fe2O3. The result of the analysis carried out on twenty seven samples showed that the mean percentage values for CaO, MgO, Al₂O₃, S_iO₂ and Fe₂O₃ for Sagamu limestone are 89.2, 1.9, 1.5, 5.7, and 5.9 respectively while that of Ewekoro showed the percentage of various oxides to be 80.3, 3.9, 2.6, 8.7, and 4.2 for CaO, MgO, Al₂O₃, SiO₂ and Fe₂O₃ respectively. The Ibeshe samples on the other hand showed the mean percentage values for CaO, MgO, Al₂O₃, SiO₂ and Al₂O₃ to be 75.7, 2.1, 3.9, 14.8, and 3.5 respectively. The depositional and biogenic features observed from slide underneath the microscope indicate that Sagamu limestone belongs to the class of Wackestone and was deposited in a lagoon environment. Ewekoro limestone belongs to the class of Grainstone and Ibese limestone belongs to classes of both Wackestone and Grainstone, all of which were deposited in an open shelf environment.


Ife Journal of Science Vol. 7(1) 2005: 101-111