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- ItemSedimentological and geochemical evaluation of sandstones of the Ilaro formation, Dahomey Basin, Southwestern Nigeria: Insights into paleoenvironments, provenance, and tectonic settings(J. Nig. Soc. Phys. Sci., 2024-02-29) A. Y. Jimoh, M. B. Saadu, A. A. Adetoro, J. Ajadi, T. Issaa, U. IssaGrain size analysis, geochemistry, and petrography of sandstones of the Ilaro Formation exposed at the Ajegunle area were investigated to infer provenance, transportation history, tectonic setting, paleoenvironment, and degree of palaeoweathering of the sediments. Selected sandstones were analyzed, and the major, trace, and rare earth elements were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results from the granulometric analysis showed that sandstones were deposited in fluvial conditions. The sandstones exhibit a coarse-grained texture, displaying poor sorting and being texturally immature. The petrographic analysis indicated that quartz was predominant, whereas opaque minerals, muscovite, and ferruginous ground mass were present in smaller quantities. The sandstones can be geochemically classified as arkose and subarenite. The sandstones have an average composition of SiO2 (82.87%) and Al2O3 (9.49%), while K2O, Na2O, MgO, CaO, and P2O5 have <1% each. The elevated Al2O3 content is associated with the lithic fragment composition, whereas the low concentrations of MgO (mean 0.03%), Na2O (mean 0.008%), and K2O (mean 0.04%) suggest chemical destruction in an oxidizing environment. The angularity of the grains indicated a short transportation history very close to the provenance. Bivariate and discriminant plots from major elements and trace elements suggest the sandstones were non-marine and sourced from intermediate rocks. The sandstones were deposited in an oxic-dyoxic condition under a humid climate and passive or active continental margins. The average values of the weathering indices indicate an intense degree of chemical weathering.
- ItemMicropaleontology 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 OlabisiThe 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.
- ItemBiostratigraphy 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 TaofeeqThe 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.
- ItemProvenance and Paleoclimatic assessment of the shales penetrated by Erekiti borehole in the Dahomey basin, Nigeria(Ilorin Journal of Science, 2024-11-03) Bolaji M; Adekeye O.A; Jimoh A. Y; Nasiru AThe shales from the Araromi Formation penetrated by the Erekiti borehole in the Dahomey basin were analyzed for their source area and paleo weathering conditions. Ten (10) samples were subjected to X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses. The major oxide revealed an abundance of SiO2 and Al2O3 (average 32.81 wt.% and 13.11 wt.% respectively) and depletion of TiO2, Fe2O3, CaO, MgO, and MnO, while the trace elements present includes an abundance of V, Cr, Zr, Sr, Zn, Ba and depletion of Sc, Co, Ni, Cu, As, Rb, Sr, Y, Nb, Mo, Pb, Th, and U. The results shows that the shales are associated to intermediate to felsic igneous origin under a very low weathering intensity. The mineralogical composition reveals quartz, gypsum, and calcite as the most abundant and the presence of other accessory minerals such as Kaolinite, K-feldspar, and plagioclase. The high percentage of quartz and gypsum confirmed the low weathering condition.
- ItemField Excursion Guide to Share-Tsonga area (part of Bida Sedimentary Basin).(Nigerian Mining and Geosciences Society (NMGS Ilorin 2016), 2016) Dada, S. S., Adekeye, O. A. and Ajadi, J.The Share-Tsonga area is part of the Bida Sedimentary Basin, known for its diverse geological features and rich sedimentary deposits. This region is significant for its natural resources and geological studies. The Bida Sedimentary Basin holds important stratigraphic records that are crucial for understanding the sedimentary processes and paleoenvironmental conditions of the area. Ecology here is influenced by its geological formations, contributing to its biodiversity and unique ecosystems. This area provides opportunities for field excursions focused on ecology and geology.