Field and Sedimentological Studies of Nataco-Banda Sediments of Lokoja Formation, Southern Bida Basin, Nigeria: Implication for Depositional Environment

Abstract

The study area falls within the Lokoja Formation of the Southern Bida Basin. The objective of this study was to evaluate the field characteristics and sedimentological parameters of depositional environment of the Nataco-Banda Sediments of Lokoja Formation, Southern Bida Basin, Nigeria using appropriate techniques such as granulometric and pebble morphometric analysis. Field studies revealed a repeated alternating sequence of conglomeratic and pebbly to coarse-grained sandstone and overbank fine sediment that is indicative of a braided fluvial source while the presence of crossbedding is suggestive of tidal influence. The morphometric analysis shows a fluvial setting where pebbles plot in the river area than the beach area. Environmental discrimination formulae for Y1, Y2 and Y3 indicated the dominance of Beach and Shallow agitated marine in both Y1 and Y2, respectively, while the almost equal percentage values of Y3 in both fluvial and shallow marine settings are highly suggestive of a shallow marine environment that is largely influenced by fluvial deposition.