Donnees geochronologiques nouvelles (U/Pb et Rb/Sr) sur la zone mobile pan-africaine du Nord Cameroun.

In North Cameroun, low-grade schists and high-grade formations were considered to represent a cover and a basement. A similar two-stage tectonometamorphic evolution has been demonstrated in both groups. U/Pb dating of zircons from deformed intrusives associated with both groups yields ages ranging from 820 to 616 m.y. A post-tectonic pluton is dated at 546 m.y. (Rb/Sr whole-rock isochron). These results confirm the Pan-African age of the mobile belt and contrary to previous interpretations show that most of the 'basement' gneisses and orthogneisses correspond actually with late Proterozoic pre-tectonic plutons.-M.L.