Palynomorph Assemblage and Palaeoecological Interpretation of Ajali Sandstone in Western Anambra Basin of Nigeria

Abstract

The study presents the lithology, palynomorph assemblage and palaeoecological interpretation of outcrops of Ajali Sandstone in Ayogwiri, Fugar and Orame in the western Anambra basin of Nigeria. The outcrops were logged and sampled. The textures range from fine sand to pebbly sand in places. Thin clay beds were also observed occurring between the basal heterolithic and sandy beds. 24 samples from selective beds were taken for foraminifera micropaleontology and palynological analysis. All samples were found to be barren of foraminifera, thus precluding age determination, but yielded few palynomorphs. Terrestrial palynomorphs dominate in the three locations with few marine dinoflagellates and acritarch occurring in Orame. The inferred palaeoecology range from humid to tropical mangrove swamps with infiltration of fresh water and marine waters. Corroborating both lithology and palynology, the depositional environment is shallower at Ayogwiri and Fugar (marginal marine) and deeper in Orame (shallow marine).

Keywords: Palynomorph, Lithology, Palaeoecology, Mangrove swamp, Pollen, Spore, Dinoflagellates.