Palynological and Paleoclimatic Study of Late Miocene Epoch Sediments of Well-‘W’, Offshore Niger Delta, Nigeria

Palynological analysis was carried out on well ‘W' in Niger Delta provincial region. Sixty-one ditch cuttings were sampled at 20 m intervals. The aim was to reconstruct the paleoclimate utilizing the abundance and diversity of the analyzed miospores within the study area. The lithostratigraphic intervals composed of predominantly fine to medium grained sand with shale intercalation conformable to the paralic Agbada Formation. The samples were subjected to palynological laboratory process which involved the hydrofluoric acid maceration and the use of other acids and bases. The recovered palynomorphs were abundant and well diversified across the sampled intervals. One hundred and seventy (170) species were recovered including the key marker species, among them are: Retibrevitricolporites obodoensis, Echiperiporites estelae, Gemmamonoporites sp, Peregrinipollis nigericus, Crassoretitricolporites vanraadshooveni, Multiaerollites fomorsus, Stereisporites sp, Cyperaceoporites sp, Nympheapollis lotus, Podocarpus milanjianus, and Retistephanocolpites gracilis. Marine forms surch as Dinoflagellate cyst, Selenopimphix sp, Spiniferites sp, Polysphaeridium sp, and Lingulodinium sp. were also encountered. Using the diagnostic marker species such as Peregrinipollis nigericus and Stereisporites sp, the age of the interpreted stratigraphic intervals was assigned Late Miocene. The wet and dry trends which were based on the variations in climate and sea level changes were transcribed employing the dispersal of Zonocostites ramonea and Monoporites annulatus. The integration of terrestrial and marine forms revealed that the sediments were deposited in shallow marine environments.