SEDIMENTOLOGICAL ANALYSIS AND DEPOSITIONAL ENVIRONMENTS OF THE NIGER DELTA: INSIGHTS FROM C-M AND BIVARIATE PLOTS

ABSTRACT

The sedimentological analysis of the Benin Formation within the Niger Delta Basin was conducted using grain size data and advanced geostatistical methods, including Cumulative Mass (C-M) and bivariate plots. This study aimed to reconstruct the paleoenvironment and delineate the depositional processes influencing sediment dynamics in the region. Thirty borehole samples were collected from two locations in Delta State (Abavo and Agbor) and two in Benin City (Isihor and Osasogie). Grain size analysis was conducted using a vibrating sieve shaker, following the Udden-Wentworth scale.The results showed significant variations in grain size distribution across the four borehole locations, with coarse sands predominating near fluvial inputs and finer sediments in more distal marine settings. C-M and bivariate plots revealed a dominance of fluvial and wave-influenced depositional environments, while minimal tidal influences were observed. Median grain size values ranged from -1.25 to 1.75 φ, and sorting values indicated moderate to very poor sorting. Skewness analysis showed predominantly fine-skewed to near-symmetrical distributions.These findings emphasize the heterogeneity of the Niger Delta's depositional environments. The prevalence of fluvial and wave-dominated processes suggests active sediment reworking and significant implications for hydrocarbon exploration and environmental management. The study provides new insights into the sedimentological processes shaping the Niger Delta, offering a basis for future research on sediment transport and reservoir quality.