Existence de dykes doléritiques anciens à composition de tholéiites continentales au sein de la province alcaline de la ligne du Cameroun. Implication sur le contexte géodynamique

Jean-Paul Vicat (1) , Ismaila Ngounouno (1) , André Pouclet (1)

1 ISTO - Institut des Sciences de la Terre d'Orléans

n the Adamawa Plateau (Northern Cameroon), doleritic dykes belong to a magmatic activity which predated the Cenozoic alkaline volcanism of the Cameroon Line. They have the chemical composition of continental tholeiites with Nb-Ta- and Ti-negative anomalies. This magmatism is interpreted as being derived from a sub-continental lithospheric source, which may have been contaminated during a former subduction event, linked to the Pan-African convergence. It is related to an early stage of continental break-up, which was contemporaneous or predated the Cretaceous tholeiitic magmatism of predominantly asthenospheric origin, which indicates a lithospheric thinning.

Mots clés: Cameroon line; dolerites; low-Ti continental tholeiites; continental extension; lithospheric magma

Domaines: Tectonique; Milieux et Changements globaux

Jean-Paul Vicat, Ismaila Ngounouno, André Pouclet. Existence de dykes doléritiques anciens à composition de tholéiites continentales au sein de la province alcaline de la ligne du Cameroun. Implication sur le contexte géodynamique. Comptes rendus de l’Académie des sciences. Série IIa, Sciences de la terre et des planètes, 2001, 332, pp.243-249. ⟨10.1016/S1251-8050(01)01526-9⟩. ⟨hal-00089827⟩