Geodynamic evolution of the Pan-African belt in central Africa with special reference to Cameroon

Abstract

The Pan-African belt in central Africa has benefited from the many petrographic, structural, and geochronological studies in the recent years that have improved our understanding of the belt. However, those studies have also produced various and often divergent evolutionary models for the belt, some of which do not even involve well-defined cratons. Following a review of the available data in Cameroon, we propose a model of continent–continent collision that involved the Congo craton and the north-central Cameroon active margin showing Archean to Paleoproterozoic inheritances. This model is based, among others, on (i) the prominent role of the Congo craton as demonstrated by the regional extension of external nappes on its northern edge and the concomitant exhumation of the 620 Ma granulitic rocks believed to have formed at the root of the collision zone, and (ii) the late development of a strike slip fault system in central Cameroon as the result of horizontal movement following the multistage collision. In the general framework of the Pan-Africano – Brasiliano belt, a comparison of the kinematic and age of deformation north of the Congo craton to that east of the West African craton, suggests that the overall tectonic evolution of the mobile domain between both cratons is controlled by their relative motion.