Palynological dating and palaeoenvironments of the M1 well, Middle Miocene, Niger Delta, Nigeria

Durugbo, Ernest Uzodimma
Olayiwola, Moshood Adegboyega
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The need to increase our knowledge of palaeo-flora is important in palaeoclimatic and palaeoenvironmental reconstruction of the Tertiary Niger Delta as to highlight possible changes in the depositional environments over time. Hence, palynological data from the M1well from the western Niger Delta region were employed in an attempt to reconstruct the Middle Miocene palaeoenvironment and palaeoclimate. The detailed palynological analysis revealed diverse and abundant palynomorph assemblages. This consisted of pollen species 60.14%, spores 25.86%, algae (Botyococcus braunii, Pediastrum sp., and Concentricytes circulus) 10.53%, miscellaneous palynomorphs (fungal elements, diatom frustules and charred Gramineae cuticle) 2.62%, dinoflagellate cysts 0.79% and acritarchs 0.06%. The well is dated Middle Miocene based on the common occurrences of diagnostic middle Miocene Niger Delta palynomorphs. Four informal palynofloral assemblage zones (MPAZ) I–IV were defined and correlated with major cycles of alternating dry and wet climatic conditions. Sediments within MPAZ I and MPAZ II were assumed to have been deposited during dominantly wet periods while MPAZ IV and III showed brief dry pulses coupled with periods of marine transgressions. The palaeoenvironment fluctuated between nearshore and marginal marine inferred from abundant records of land-derived palynomorphs and the spotty records of the dinoflagellate cysts Nematosphaeropsis labyrinthus, Nematosphaeropsis lemniscata and Impagidinium sp.
palynomorphs, Niger Delta, Miocene, palaeoclimate