The sedimentary and tectonic features of the Niger Delta

Abstract

The Niger Delta, one of the largest delta in the world, is located on the eastern passive continental margin of the Atlantic Ocean. It was formed during the Niger River entering the Atlantic Ocean. The main part of the delta lies on the Atlantic oceanic crust, and the minor part on the African pre-Cambrian basement. The Central and West African Rift Systems indirectly control the formation of the Niger Delta through controlling the distribution and development of the Benue-Niger river system. It is a prograded delta with typical prograding sequence, i.e., regressive sequence. The prograding sequence is constituted with the marine shale (Akata Formation), paralic sand and shale (Agbada Formation) and continental alluvial sands (Benin Formation) from the bottom to the top. These three lithostratigraphic units are diachronous. All of them are younger seaward. There is a large scale gravity gliding tectonics. The main detachment fault lies in the Akata marine shale. The gravity tectonics can be divided into the front compressional deformation province and the trail extensional deformation province. The front compressional deformation formed a fold-thrust belt. The trail extensional deformation formed horst-graben structures. The detachment folds are well developed in the transitional zone between these two deformation provinces. Accompanied with the gravity-gliding tectonics, shale tectonics are widely developed in the Niger Delta. There is possibly some formation-relation between the gravity-gliding tectonics and the Cenozoic volcanic activities of the Cameroon volcanic line.