Planktic and Benthic Foraminiferal Forms; Evidence for the Influx of Benguela / Canary Current into Part of the Gulf of Guinea (Niger Delta), Nigeria during the Late Eocene – Early Oligocene

Abstract

Planktic and benthic foraminifera are useful in deciphering past climatic conditions and palaeocirculation patterns since their ratio, abundance and diversity of the planktic foraminiferal test as well as the ratio, abundance and diversity of the shell types of the benthic foraminiferal preserved hold significant records. This research attempts to use foraminiferal forms for palaeocirculation analysis. Information from three (3) deep wells that tested the Eocene – Oligocene interval in the Niger Delta was utilized for this study and standard foraminiferal sample preparation method was employed. The sea-level history of the study wells show an overall transgressive episodes with intermittent regressive phases characterized by alternation of sandstone and shale. The foraminiferal assemblages recovered from the study wells are associated with clastic deposition and occur as shallow inner neritic - outer shelf assemblages. The distribution pattern of the planktic foraminifera is dominated by Globigerinaspp. with a few Globorotalia spp. This distributional patterns together with the low diversity of foraminifera as well as the presence of subarctic – subantarctic forms depict periods of cold water influx into the Gulf of Guinea (Niger Delta) from the Canary or the Benguela current during the Late Eocene (Priabonian) – Early Oligocene (Rupelian) epoch therefore affecting the normal regional warm water circulation that characterize tropical regions. The dominance of the hyaline and arenaceous test over the hyaline and porcelaneous test further support this interpretation. This indicate significant oceanic heat exchange during the Priabonian – Rupelian age which in turn influenced the distributional patterns of foraminiferal forms in the Niger Delta.

Publication Info:

Author: Ukpong, A.J. and Ekhalialu, O.M.

Volume: 57

Issue: March

Published By: Journal of Mining and Geology, 2024-03-01