Textural and Paleoenvironmental Characterization of the Campano-Maastrichtian Patti Sandstone, Southern Bida Basin, Northcentral Nigeria

Abstract

Field and granulometric investigation of Patti Sandstone were carried out with a view towards establishing the lithological sequence, geological processes, textural characteristics and paleoenvironment of deposition of the sediments. Field study entailed basic field procedures and sedimentological descriptions which encompass physical factors such as textural parameter, composition, colour and structures; biological inference in terms of fossil content and chemical character in terms of chemical composition and post depositional diagenesis effect. Granulometric laboratory procedure includes weighing and sieving of samples with set of sieves; calculated cumulative percentages, software input of data to generate statistical parameters such as mean, standard deviation (sorting), skewness, kurtosis and ternary diagrams. Field observations show that the lower part of the outcrop section has alternation of claystone and shale; the mid-section shows coarsening-up sequence of shale, clay and sandstone facies of a retrogradational system, while the upper part is composed of intercalation of claystone and sandstone in repetitive pattern, various thicknesses and colours. The textural characteristics of the sandstone are generally coarse-fine grains, reddish to greyish in colour, rounded to subrounded and moderately to well sorted. Structurally, the outcrops are planar cross bedded, wavy laminated and concretional. Granulometric result categorized the sandstones into fine, medium and coarse grained particles; well sorted to moderately well sorted, characterized by lateral retrogradational sequence from the shoreline. The skewness varies from fine skewed, very fine skewed and symmetrical. Kurtosis values suggest multi-sourced particles deposited in marine and fluviatile paleoenvironments.