LITHOFACIES ANALYSIS AND TEXTURAL CHARACTERISTICS OF EOCENE NANKA SAND, SOUTHEASTERN NIGERIA

Abstract

Granulometric and lithofacies analysis were employed in the study of Nanka Sand in order to determine the environment of deposition of the sediments. Granulometric analysis of the sands shows that the sands are predominantly fine skewed, leptokurtic and moderately sorted. The sands plot in the river compartments on the environmental discrimination diagrams of Stewart (1958), Friedman (1961) and Moiola and Weiser (1968). Three lithofacies were deduced: wave rippled fine sand facies, cross bedded fine sand facies and heterolithic facies. Sedimentary structures include mud flasers, planar and trough cross beds, wavy and parallel laminations, ripples, tidal bundles, mud drape, reactivation surfaces, concretions and burrows, indicative of tidally influenced environment. The plots of thickness vs serial positions of the planar cross beds suggest tidal fluctuation (rhythmic) while the rose diagram shows bimodal- bipolar paleocurrent flow which were from Westerly and Northeastern direction