Biostratigraphy and Palaeoecological Studies of the Late Cretaceous-Tertiary Sediments in the Dahomey Basin, Nigeria
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Date
2022-07-25
Journal Title
Journal ISSN
Volume Title
Publisher
European Journal of Environment and Earth Sciences
Abstract
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.