Benue Trough

The Benue Trough is a major geological structure underlying a large part of Nigeria and extending about 1,000 km northeast from the Bight of Benin to Lake Chad.

The Anambra Basin in the west of the lower region is more recent than the rest of the trough, being formed during a later period of compression, but is considered part of the formation.

[1] In the Upper Cretaceous, the Benue Trough probably formed the main link between the Gulf of Guinea and the Tethys Ocean (predecessor of the Mediterranean Sea) via the Chad and Iullemmeden Basins.

When separation was complete, the southern part of Africa swung back to some extent, with the sediments in the Benue Trough compressed and folded.

[6] During the Santonian age, about 84 million years ago, the basin experienced intense compression and folding, forming more than 100 anticlines and synclines.

[7] The same plume may be responsible for the line of volcanoes in Cameroon along the Central African Shear Zone and for the volcanic island of St. Helena in the Atlantic Ocean.

[2] During this time, the Anambra Basin became silted up with thick vegetation growing in low-lying marshes on a broad delta fan deposited by rivers from the interior.