Sedimentary Structures of Ajali Sandstone

Abstract

The Ajali Sandstone is a Maastrichtian deposit in the Stratigraphic units that make up the Anambra basin, southeastern Nigeria. The approximate locations of the study areas; Okigwe and Uturu, are respectively Latitude 5˚45’N-6˚00’N &Longitude 7˚15’E – 7˚30’E and Latitude 5˚48’N-5˚55’N & Longitude 7˚25’E-7˚30’E. Samples were collected for further laboratory studies and the result showed that the Ajali Sandstone is dominated by quartz mineral grains which constitute about 67.23% modal composition with ironstone cementing material. This implies that Ajali Sandstone is basically quartz arenite and it is said to be mineralogically mature. The Ajali Sandstone as observed in the field is milky white in color and friable with intercalations of claystone, mudstone, and shale. Common sedimentary structures observed on the Ajali Sandstone are cross-stratification structures, lamination structures, wavy structures, biogenic structures, herringbone cross-stratification, clay drapes, and heterolytic structures, These are indicative of fluvial-marine and continental depositional environment.