Surrounding Plate
The Cameroon line bisects the angle where the coast of Africa makes a 90° bend from the southern coast along the west of the Congo craton and the western coast along the south of the West African craton. The coastline roughly corresponds to the coast of the Borborema geological province of northeastern Brazil, which began to separate from this part Africa around 115 million years ago.
The Central African Shear Zone (CASZ), a lineament that extends from the Sudan to coastal Cameroon, runs under the continental section of the Cameroon line. It is visible in the Foumban Shear Zone, which was active before and during the opening of the South Atlantic in the Cretaceous period. The western end of the shear zone is obscured by the volcanoes of the Cameroon line, but based on reconstruction of the configuration of South America before it separated from Africa, the Foumban Shear Zone can be identified with the Pernambuco fault in Brazil. A major earthquake in 1986 could indicate that the shear zone is reactivating.
The Benue Trough lies to the west of the Cameroon line. The Benue Trough was formed by rifting of the central West African basement, beginning at the start of the Cretaceous era. A common explanation of the trough's formation is that it is an aulacogen, an abandoned arm of a three-armed radial rift system. The other two arms continued to spread during the break-up of Gondwana, as South America separated from Africa. During the Santonian age, around 84 million years ago, the Benue Trough underwent intense compression and folding. Since then it has been tectonically quiet.
Read more about this topic: Cameroon Line, Geology
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