Pan-African tectonics in northwestern Cameroon: Implication for the history of western Gondwana

Three main tectonic events related to Pan-African collision and post-collision evolution have been identified in Cameroon: i) crustal thickening; ii) left lateral wrench movements; and iii) right lateral wrench movements, successively. Correlation of these events throughout the Pan-African belt, and an integrated synthesis that includes the domains of Central Africa, Trans-Sahara and NE Brazil, enable us to define an indent-type structure in northwestern Cameroon. This one suggests the existence of a rigid prong in this area which collided with the São Francisco–Congo Craton (SFCC) active margin at ca 640 Ma prior to subsequent widespread remobilization and granitization that partly affected both landmasses between 640 and 580 Ma. Major indent-related shear zones were further reactivated during regional clockwise rotation of the newly stabilized domain of northwestern Cameroon, suggesting that collision with the West African Craton (WAC) was still active after 580 Ma. Geodynamic implications of this model are discussed in the context of the Pan-African global evolution in western Gondwana.