Palaeontologia africana

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ISSN (print): 0078-8554 ISSN (electronic): 2410-4418 For queries regarding content of Palaeontologia africana collections please contact Jonah Choiniere by email : jonah.choiniere@wits.ac.za or Tel : 011 717 6684

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2016 - 20172

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    Palynological dating and palaeoenvironments of the M1 well, Middle Miocene, Niger Delta, Nigeria
    (2017-07) Durugbo, Ernest Uzodimma; Olayiwola, Moshood Adegboyega
    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.
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    Palynostratigraphy, palynofacies and thermal maturation of the Nsukka Formation from an excavation site in Okigwe, Southeastern Nigeria
    (2016-03) Durugbo, Ernest Uzodimmaa
    There is a dire need to assess the petroleum generating potential of the Nigerian inland basins. The Nigerian Federal Government has in the last few years demarcated the inland basins, of which little is known palynologically, for oil and gas exploration activities. An input from Nigeria concerning events of the Cretaceous -Paleogene boundary would broaden our knowledge of the global event. This palynological study of the Nsukka Formation from an excavation site in Okigwe, Southeastern Nigeria, revealed abundant records of pollen, spores and dinoflagellate cysts. Palm pollen Longapertites marginatus, L. vaneendenburgi, L. microfoveolatus, Spinizonocolpites echinatus, S. baculatus and Foveomonocolpites bauchiensis dominated the microfloral assemblage with common dinoflagellate cysts, especially Ifecysta spp., Cordosphaeridium spp., Fibrocysta spp., Senegalinium spp., Cerodinium spp., Phelodinium spp., Spiniferites spp. and Hafniasphaera spp., indicating alternating shallow to marginal marine depositional environments. The already published ranges of the palynostratigraphically important taxa such as Buttinia andreevi, Monocolpopollenites sphaeroidites, Rugulatisporites caperatus, Zlivisporis blanensis, Cingulatisporites ornatus, and the earliest Danian dinoflagellate cyst markers Damassadinium californicum, Carpatella cornuta, Hafniasphaera septate and Senegalinium bicavatum, enabled the delineation of the age as Late Maastrichtian-Middle Paleocene. The studied Nsukka sequences consist of alternating successions of fine grained sandstones, well bedded dark and sandy shales. The samples were dominated by terrestrial organic components, especially structured phytoclasts, black debris and unstructured phytoclasts/degraded wood elements, indicating deposition in predominantly nearshore environments, coupled with the dominance of peridinoids over gonyaulacoids. However, the basal samples were characterized by common amorphous organic matter co-occurring with dinoflagellate cysts suggesting brief periods of marine transgressions. Using Deltoidospora adriennis as an index, the spore colouration index (SCI), ranged from 4 (golden yellow) to 4.5 (deep yellow) which correlates to vitrinite reflectance values of 0.4 - < 0.5, indicating that the sediments were immature for oil and gas generation.