Sedimentary petrology and provenance interpretation of the sandstone lithofacies of the Paleogene strata, south-eastern Nigeria

Abstract

The Paleogene strata in the south-eastern Nigeria include the Imo Formation, the Ameki Group and the Ogwashi Formation. Petrographic studies suggest quartz arenite to arkosic arenite and sub-arkose for sandstones of the Imo Formation. Sandstones of the tide-dominated estuarine system of Ameki Group are classified as quartz arenites, sub-arkoses, sub-litharenites and litharenites. Sandstones of the Ogwashi Formation are classified as quartz arenites and sub-litharenites. These Paleogene sandstones are derived from mixed provenances based on the petrographic interpretation. The provenances include cratonic interiors, transitional continental blocks as well as recycled orogenic and transitional continental, transitional recycled and quartzose recycled. Paleoclimatic condition for the Paleogene region is semi-humid to humid climate. The sandstone composition suggests detritus from igneous rocks, metamorphic rocks and recycled sedimentary rocks. Heavy mineral analysis confirms the possibility of mixed provenance for the Paleogene sediments. The source areas include the Oban Massif, the West African Massif and the recycled sedimentary rocks of the older sedimentary rocks of probably the Anambra Basin and Afikpo Syncline.