Paleo-environmental deduction from pebble morphometry and textural studies of sandstone deposits of Isuochi and Environs, Anambra Basin, South Eastern Nigeria

Abstract

Textural analysis and pebble morphomentric were carried out on the sandstone deposits of Isuochi area in Anambra Basin, in an attempt to  reconstruct the paleoenvironment of deposition. Field observation shows that the sandstone samples, collected from various locations were  analyzed for sieve analysis, while two hundred fresh quartz pebbles that are greater than 2.00mm in diameter were collected for pebble  morphomentric. Morphomentric parameters include; elongation ratio, flatness index, oblate index, and maximum projection sphericity were computed. Bivariate plots of Maximum Projection Sphericity against Oblate Prolate Index show that about 69% of the pebbles are of fluvial origin,
while 31% is surf, bivariate plots of Flatness Index against Maximum Projection Sphericity show that about 57% is of fluvial origin, while 43% show surf; these imply that the associated pebbles are of fluvial origin. Bivariate plots of sandstone textural parameters such as skewness against standard deviation also suggest that the sediments are more of fluvial origin while multivariate parameter shows partly shallow marine  environment.

Keywords: Pebble Morphometry, Oblate-Prolate Index, Paleoenvironment.