Ciências Marinhas: Pesquisa e Desenvolvimento

Abstrato

Morphology of the Niger Delta: Local Facies Belts Orientation versus Depobelts and Growth Fault Orientations

Durogbitan A Abimbola

This work presents for the first time, evidence and the relationship between the ancient coastal belt and the modern coastal belt in terms of local facies belts orientation versus depobelt and fault orientations within the Niger Delta. This observation suggests that the ancient coastal belt of the delta is more lobate /arcuate than the modern Niger delta. The delta became broadly convex to the sea during the late Miocene. Deltas are influenced by a variety of fluvial and marine processes and these processes controlled their morphology. The most widely used classification scheme today is that of Galloway who subdivided delta according to their dominant processes i.e. rivers, waves and tide. Fluvially dominated deltas tend to display lobate-elongate morphology, e.g. the Balize delta- Mississippi. In contrast wave-dominated deltas tend to be more lobate and have smooth, arcuate to cuspate margins, e.g. the Nile delta. Tide dominated deltas tended to be estuarine to irregular in geometry. Although the Niger delta has been characterized to be mixed influenced delta showing the combination of the effects of river, wave and tidal processes, the modern Niger delta has been described to be more wave dominated and more lobate, and the classification falls within the wave dominated section on Galloway classifications. This implies that during Miocene, the delta was more fluvially dominated in relation to sediment supply and basinal processes (wave and tide). This also implies that the modern Niger delta cannot be used as a direct analogue for the ancient delta.