Late Cretaceous - Paleocene deposits in Afikpo sub-Basin, Southeastern Nigeria: Evidence from Palynomorphs

Thirty sediment samples of surface outcrops from Afikpo and Uturu areas in the Afikpo sub-Basin of Anambra Basin has been studied for palynological composition. This investigation was necessitated by the need to reevaluate the stratigraphy of Afikpo sub-Basin using palynomorphs as new outcrops were exposed in road cuts and pits. The samples studied yielded 40 species of palynomorphs at the Afikpo area and 30 species from Uturu axis. The palynological specimens recovered across the studied areas were moderate to low in yield. A total of 1060 specimens were counted from Afikpo samples and 380 from Uturu area. Longapertities marginatus assemblage zone and Apectodinium homomorphum zone are the two palynological zones that were defined in the studied areas. The new zone (Apectodinium homomorphum) defined in the studied area has led to the delineation of Nsukka Formation in Afikpo sub-Basin. The botanical affinity of the recovered palynomorphs shows that the recovered palynomorphs is dominated by palm pollen, and pteridophytic spores (especially taxa related to aquatic fern), and dinocysts. The ecological zones interpreted from the palynological taxa present are tropical rainforest, mangrove/coastal environment, freshwater wetlands and marine ecosystem. The recovered palynomorphs are correlatable to other Cretaceous basins in Nigeria, West Africa, South America, India and other low latitude areas.