Textural Characteristics and Depositional Processes of Sediments from a 47 km Transect in the Niger Delta, Southern Nigeria

Abstract

120 sediment samples collected along a 47 km transect from Ikot Abasi to Eket, Akwa Ibom State were subjected to granulometric analysis to determine their textural characteristics and depositional processes. Standard sedimentological methods involving sieve analysis were utilized to determine the various size distributions for each sample. This was further subjected to statistical treatment (mean size, sorting, kurtosis, skewness, bivariate and multivariate analyses). Results show that the samples were very fine to pebbly (3.23 to -1.53) Ø diameter in size and varies from very poorly sorted to very well sorted (2.069 to 0.294) Ø with about 86% of the samples being poorly sorted. The sediments are predominantly leptokurtic (91%), with only few (9 samples) being platykurtic (range 8.148 to -1.082) Ø and are coarse to very fine skewed in nature. The dominant modes of transportation reflected by these sediments are saltation and surface creep attributed mostly to current and channel action. Bivariate analysis revealed that most of the sediments are associated with fluvial processes of deposition with beach processes being subordinate. Multivariate analysis showed that shallow marine agitated environment mostly characterized the sediments of this study area. CM pattern for the sediments reveal deposition was mainly by graded suspension to bottom suspension and rolling. These features characterize sediments deposited by fluvial processes dominated by tractive current patterns in a shallow marine depositional environment.