Evolution of the Niger Delta, present dynamics and the future
Evolution of the Niger Delta is closely linked to the geodynamics related to the separation of the African and South American continents and the tectonics of the formation of the Benue Trough. Tectonic activities, climate and eustasy are the major factors responsible for transgression and regression through the entrant point along the present Niger Delta area and the deposition of marine and non-marine sediments from late Aptian to Eocene. The Santonian and later Campanian to Eocene positive movements of blocks bounded by NE-SW and NW-SE trending faults along the Benue Trough and the present Niger Delta region preceded the subsidence of the Oligocene and younger Niger Delta basin along the NW-SE fault trends. From Paleocene to Eocene, the Anambra basin was filled by the transgressive Imo Shale, the regressive Ameki Formation and from Eocene to Recent the Niger Delta has been filled by Akata, Agbada and Benin Formations. At present rifting and tectonic subsidence are dormant but the basin is under a sag regime with continued deposition of Benin Formation and little changes in climate and eustasy. The present dynamics in the Niger Delta has evolved it to a near mature basin but a climate change with the resultant eustasy could destabilize the ecosystem of the region with corresponding economic consequences.
Keywords: Niger Delta; Transgression; Regression; Eustasy; Evolution; Paleogeography