Grain Size Analysis of Sediments From Okpoama – Brass Beach in the Niger Delta

Edirin Akpofure ,S Tombra Akana

doi:10.7176/jees/9-3-09

Abstract

Granulometric analysis was carried out on sixty – three sediment samples collected from the Okpoama – Brass Beach, in the Niger Delta, to determine the particle size distribution, the nature of the sediments and transport mode of the sediments. The sediment population is predominantly unimodal, with the 0.25 – 0.125 mm (fine sand) as the modal class, though, a significant population are polymodal. Sorting ranges from 0.1 (very well sorted for the unimodal samples) to 1.01 (poorly sorted for the polymodal samples). The average sorting value for the entire sampled population is 0.89 (Moderately sorted). The skewness of the population range from symmetrical to negatively skewed. The average values for the kurtosis is 1.2 (Leptokurtic). The average value for the Median (φ) is 1.92 which represents the medium sand size grade, while the average Mean value is 1.95 φ. The predominant mode of transport is by saltation for the modal class, and suspension and traction for the finer and coarser sediments respectively. The sediment load from Okpoama – Brass beach are dominantly fine sands, indicative of distant source rock and a gentle depositional slope. Keywords: Beach. Grain size analysis, Unimodal, Mean value, Cumulative curve, Saltation. DOI : 10.7176/JEES/9-3-09 Publication date :March 31 st 2019

Highlights

Okpoama – Brass beach is located in Bayelsa State, which is a lowland state with a lot of tidal flats, coastal beaches, beach ridge barriers and flood plains
Okpoama – Brass beach is one of the active beaches that sit at the edge of the Atlantic Ocean
Each transect included the sampling of the sand dunes, backshore and beach face deposits where possible, otherwise only two samples were collected from sections of the beach that was reachable in that transect

Summary

1.Introduction

Okpoama – Brass beach is located in Bayelsa State, which is a lowland state with a lot of tidal flats, coastal beaches, beach ridge barriers and flood plains. Features such as cliffs and lagoons are the dominant features of the state. It is a long narrow accumulation of sand parallel to the shore line. The Niger Delta complex comprises the sediment load of Mid Eocene to Recent age It is bordered by the Atlantic Ocean in the South and to the North by an acuate line which runs roughly through Benin, Onitsha, Umuahia, and slightly SSW of Calabar. The Benin Formation is overlain with the Quaternary sediments (Table 1, Allen, 1965)

3.Methodology

Presentation of Samples and Description

Conclusion