The textural properties and depositional processes of 120 sand samples collected over a 47-kilometer transect from Ikot Abasi to Eket in southern Nigeria were determined using granulometric analysis. The varied size distributions for each sample were determined using standard sedimentological procedures such as sieve analysis. The fluidity factor of the depositing medium and the energy factor of the deposition environment are reflected in the sediment size distribution. This was also subjected to statistical analysis (mean grain size, median, sorting, kurtosis, skewness, bivariate and multivariate analyses). The samples range in size from extremely fine grain to pebbly (3.23 to -1.53) in diameter, and are sorted from very poorly to very well (2.069 to 0.294), with around 86 percent of the samples being badly sorted. The sediments are mostly leptokurtic (91%) with only a few (9 samples) platykurtic (range 8.148 to -1.082) and coarse to extremely fine skewed in character. Saltation and surface creep, mostly due to current and channel action, are the major modes of conveyance recorded by these sediments. Bivariate analysis revealed that the majority of the sediments are related to river deposition processes, with coastal processes taking a back seat. The sediments of this study area were generally characterised by a shallow marine disturbed environment, according to multivariate analysis. The sediments were deposited mostly via graded suspension to bottom suspension and rolling, according to the CM pattern. In a shallow marine depositional environment, these characteristics identify sediments deposited by fluvio-deltaic processes dominated by tractive current patterns. The sediments throughout the transect analysed reveal energy setting linked with a combination of high and relaxed energy at various points during the depositional process, as evidenced by their moderate sorting, which is generally positively skewed and leptokurtic.
Author(s) DetailsE. E. Okon
Department of Geology, University of Calabar, Calabar, Nigeria.
N. U. Essien
Department of Geosciences, Akwa Ibom State University, Mkpat Enin, Nigeria.
A. O. Ilori
Department of Civil Engineering, University of Uyo, Uyo, Nigeria.
S. N. Njoku
Energy and Mineral Resources Ltd, Lagos, Nigeria.
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