Browsing by Author "Adekeye, Adeleye Olabisi"

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    Biostratigraphy and Palaeoecological Studies of the Late Cretaceous-Tertiary Sediments in the Dahomey Basin, Nigeria
    (European Journal of Environment and Earth Sciences, 2022-07-25) Saadu, Bolaji Mariam; Jimoh, Ayoola Yusuf; Adekeye, Adeleye Olabisi; Issa, Ayinde Taofeeq
    The Maastrichtian–Eocene sediments (mainly shales and limestones) penetrated by the Itori borehole and Ilaro boreholes in the Dahomey Basin were investigated for foraminiferal biostratigraphy and palaeoecological interpretation. These boreholes penetrated Araromi, Ewekoro, and Oshosun formations at varying depths. Selected shale sediments were subjected to foraminiferal analysis and many planktonic and benthic species of foraminifera (agglutinated and calcareous) were recovered from the Cretaceous interval of the penetrated boreholes. Twelve species of planktic foraminifera (Globalomalina planocompressa, G. pseudomenardii, Globigerina inaequispira, Acarinina cf.coalingenis, Acarinina nitida, Chiloguembelina cretacea, chiloguembelina subtriangularis, Orthokasrstenia sp., Hedbergella holmdelensis, Globigerina sp., Globigerinelloids asperus, Morozovella formosa formosa) and thirteen species of benthic i.e Bolivina sp., B. Crassicostata, , E. africana, Eponides psuedoelevatus, Gavelinella cf. guineana, Gavelinella pachysuturalis, Haplophragmiodes sp., Lenticulina cyprina, L. inornata, L. olokuni, L. psuedomamilligera, L. taylorensis, Nonionella communis, N. spissa, N. panamensis, Orthokarstenia sp., Planulina oyae) were identified. In general, benthic species of infauna deposit feeder and epifauna dominate the population. These species occupy a range of environments from dyoxic to anoxic, brackish water to marsh environment down to upper bathyal depth. Based on the abundant and stratigraphical distribution of the foraminiferal species, four biostratigraphic zones were recognized: Afrobolivina afra zone of late Maastrichtian, Globigerina zone of early Paleocene, Globalomalina pseudomenardii zone of late Paleocene and Morozovella formosa formosa zone of the early Eocene.
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    Micropaleontology and inorganic geochemical studies of the Campanian-maastricthian shale sediments in the Anambra and southern Bida basins Nigeria: Implication for provenance and paleoenvironment
    (Journal of African Earth Sciences, 2024-06-24) Bolaji, Mariam; Adekeye, Adeleye Olabisi
    The Micropaleontology and Inorganic Geochemical analysis were carried out on the shales of Enugu and Patti Formations (Anambra and Southern Bida Basins) deposited during the Campanian-Maastrichtian time interval to evaluate the connectivity of the paleo-sea depositional environment and sediments source. The method of analysis employed includes field sampling of two exposed sections of the formations and laboratories analyses which includes foraminiferal studies, Xray Fluorescence spectrometry (XRF) and Xray diffraction analysis (XRD). 30 selected shale samples were used for these analyses. The lithologic sections presented shows similarities in the reconstructed visible layers of sediment by the exposed sections in the two formations. The foraminiferal analysis revealed abundance of Benthic species depicting a shallow marine environment for the deposition of the sediments. The Benthic species recovered includes, Ammobaculite coprolithiformis, Ammobaculites exiguus, Ammobaculites strathearnensis, Ammobaculoides parvus, Ammomarginulina cf. A. curvature, Bolivina afra, Eponides sp, Haplophragmoides bauchensis, Haplophragmoides bausa, Haplophragmoides saheliense, Lenticulina cultrataspecies, Miliammina petila, Nonionella robusta, Praebulimina bantu, Textularia hockleyensis and Textularia parvula. The XRF analysis results of the selected shale samples of the two formations revealed SiO2 as the dominant oxide (Average Enugu-87.06 wt % and Patti-62.42 wt %). The Al2O3/TiO2 ratios in the two formations suggests that source rocks of these formations are likely to be transitioning from mafic to intermediate rock composition. Plot of SiO2/Zr display positive correlation in the shale of the Patti Formation to indicate lack of biogenic silica while showing negative correlation in that of Enugu Formation suggesting favorable environment for biotic life. Also, the plots of TiO2/Zr and TiO2/Al2O3 described both formations as intermediate rock composition for provenance. The plot of V/Ni revealed both formations as marine anoxic paleoenvironments. The Xray diffraction analysis reveals abundance of quartz and small amount of accessory minerals like goethite, kaolinite, smectite, mica, anatase, siderite and calcite.