Miospores (Spores and Pollens) and Lithofacies of Maastrichtian Sediments of the Benin Flank, South Western Anambra Basin, Nigeria

ABSTRACT The study area which is part of the Nkporo Group lies within the Benin flank of the Anambra basin. This study is aimed at reconstructing the palaeoenvironment of the Nkporo shale outcropping in this part of the basin through field relationship, micropalynological, and sedimentological studies. Scanning Electron Microscope (SEM) as well as Transmitted Electron Microscope (TEM) were used to study the external and internal features of associated spores and pollens; and through sculptural studies, the miospores found in the shales of Orhua and environs have different morphological features such as striate, clavate, psilate, scabrate, and reticulate. Grain size analysis indicated that the sandstones are medium grained, very poorly sorted, near symmetrical and very platy-kurtic. A close overview of these results revealed that the sediments were deposited in fluvial-beachshallow marine settings under rainforest vegetal cover. It can also be deduced that the palaeoclimate and palaeo-vegetation has not varied too much since their deposition in Maastrichtian. The field data show that the shales are fissile, light to dark grey with intercalations of fine to medium grained sands. The fissility of the shales suggests that they were deposited in low energy environment, distal to proximal marine environment. The occurrences of these sandy intercalations within the shales are likely indications of fluvial influence during deposition