PALEOENVIRONMENTAL RECONSTRUCTION AND AGE DETERMINATION OF SEDIMENTS FROM SHEET 288 BENIN FLANK OF NIGER DELTA SEDIMENTARY BASIN, NIGERIA

Abstract

A palynological study was carried out to elucidate the presence of pollen and spores and other microscopic sized structures to reconstruct ancient environment of deposition and determine the age of sediments obtained from sheet 288 Benin Flank of Niger Delta Sedimentary Basin, Nigeria. Nineteen (19) core samples were collected at interval of 3m from a section of a well ranged 605 – 663 metres depth and fifty Seven (57) metres thick. The samples were macerated (grinding to powder) and treated with Hydrochloric (HCL) and Hydrogen Fluoride acid (HF) respectively to remove the silicate cementation and the carbonates to obtained organic residues which was prepared into slide for petrographic analysis. The following Palynomorphs, Miospores and dinoflagelates; Monoporites annulatus, Psilacolporites crassus, Zononolporites ramone, Sapotaceo, Laevigatos, Cynathiditesminor, Acrostichumaureum, Longapeitities sp. Verrucatosporites usmensis Verrucatosporites sp. and Aduntosphoridinium were recovered from the sediments. These fossils were compared with the standard work of Jan du Chene and others which gave an age of middle to upper Eocene. The lithological deductions as well as the presence of some index fossils such as Laevigatosporites ovatu, P. Crassus indicated that the sediments were deposited in a coastal deltaic/mangrove swamp environment. Ultimately, the findings correlate with Ameki Formation, which has its depocenter in Anambra Basin, eastern Nigeria.