Monday, 7 February 2011

The evolution of geological tectonics in the Niger delta, Nigeria

1)                       DEFINITION OF TECTONICS:
          Tectonics is the study of the origin and arrangement of broad structural features of earth’s surface, including not only folds and faults but also mountain belts, continents, and earthquake belts. It can also mean large scale processes affecting the structure of the earth’s crust.
2)                       THE NIGER DELTA
           The Tertiary Niger Delta petroleum is one petroleum system in the Niger Delta province. This Tertiary Niger Delta  petroleum system is also known to be the Akata-Agbada petroleum system. The delta formed at site of a rift triple junction related to the opening of the southern Atlantic starting in the late Jurassic and continuing into the cretaceous. As at the Eocene, the delta proper began developing and accumulating sediments that are over 10 kilometers in thickness. The primary source rock is the upper Akata formation, the marine-shale facies of the delta, contributions from interbedded marine shale of the lowermost Agbada formation. The Agbada formation consists the sandstone facies. Oil is produced from sandstone facies within the Agbada formation. To be precise, turbidite sand is found in the upper Akata Formation is a potential target in deep water offshore and possibly beneath currently producing intervals onshore.
It is important to know that Niger Delta is situated in the Gulf of Guinea and extends throughout the Niger Delta province as defined by klett and others (1997). From Eocene to the present, there was progradation of the delta towards the south-west, which resulted in formation of the depobelts that represent the most active portion of the delta at each stage of its development. About 300,000km2 makes up the area of the depobelts, which form one of the largest regressive deltas in the world.
The onshore portion of the Niger Delta Province is delineated by the southern Nigeria and southwestern Cameroon. The northern boundary is the is the Benin flank, which is an east-northeast trending hinge line south of the west Africa basement massif. The offshore boundary of the province is defined by the Cameroon volcanic line to the east, the eastern boundary of the Dahomey basin to the west and the two-kilometer sediment thickness contour. The province covers 300,000km2 and includes the geologic extent of the Tertiary Niger Delta petroleum system.

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