The sedimentological and foraminiferal content of gravity cores collected from the continental shelf and upper slope off the Niger delta, West Africa, have been studied. Careful study of the cored sediments has allowed the identification of characteristics which distinguish exposed sediments which are partly or wholly relict in composition from deduced non-relict (modern) sediments. The faunal content of modern sediments has been compared with the known oceanographic conditions, and the identified qualitative relationships have been shown to be useful for palaeoenvironmental interpretation. The depth distributions of the modern faunae appear to be largely influenced by temperature, and faunal breaks have been found to correlate with the upper and lower limit of the regional thermocline. Species which are apparently endemic to the Gulf of Guinea and West Africa are largely confined to the near-surface water and species characteristic of the upper and middle slope are generally widespread geographically. Relict sediments exposed near the shelf edge are characterized by Amphistegina gib-bosa which is not believed to be living in the modern Gulf of Guinea. The disappearance of A. gib-bosa appears to correlate with an increase in freshwater discharge of the Niger distributaries soon after 11,500 B.P. The more recent relict faunae are similar to the present and apparently document the rise in sea level. There is no evidence that any of the cored sediment was deposited in an environment other than an exposed shelf.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637229 |
| Date | January 1981 |
| Creators | Harris, D. K. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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