Sedimentological and geochemical studies of Maastrichtian clays in Bida Basin, Nigeria: Implication for resource potential
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Date
2011
Journal Title
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Publisher
Centrepoint Journal (Science Edition), University of Ilorin
Abstract
Bida Basin is located in the central part of Nigeria, trending northwest southeast. Present study is focused on the claystone units of the Maastrichtian Patti and Enagi Formations in southern and northern Bida Basins respectively, to determine the paleoenvironments, geochemical and geotechnical properties and, assess the economic potential of the clay deposits. At Share, towards the middle part of the Enagi Formation section, cream to white claystone beds are interbedded with cross to parallel stratified quartzarenitic sandstones. In the Patti Formation section at Agbaja, white, massive claystone beds are interbedded with herringbone and hummocky cross stratified sandstones. Gross sedimentological features suggest that the associated sandstone facies were deposited in tidal channel to shoreface environments whereas the claystone probably represent a low energy floodplain sub environment. Geochemical data show that the claystone at Share is composed of SiO2 content ranging from 45.2% to 64.8% (average of 58.1%) while at Agbaja, the values range from 48.5% to 74.7% (average of 63.3%). Al2O3 value for the clay at Share ranges from 20.3% to 37.9% (averaging 26.9%) while, the Agbaja samples is between 15.61% and 34.23% with an average of 24.6%. These indicate that the clays are essentially hydrated siliceous aluminosilicates. Relatively low abundance of MgO and K2O (less than 0.30%) indicate lack of expandable clay mineral in the samples. Plastic limit less than 30% indicates that clays are kaolinitic. Average Plastic Index for the Share and Agbaja clays are 24.29 and 17.7% respectively and the shrinkage limit values (average) are 10.05% and 2.66%. The clays compare favourably with the Plastic fire clay of St. Louis and Florida active kaolinite. Their characteristics are quite consistent with other sedimentary kaolin deposits in Nigeria. They also show low heavy metal concentrations and thus may be beneficiated and suitable as raw materials for ceramic, pharmaceuticals and paints.