U-PB AND SM-ND PRELIMINARY GEOCHRONOLOGICAL DATA ON THE YAOUNDE SERIES, CAMEROON - REINTERPRETATION OF THE GRANULYTIC ROCKS AS THE SUTURE OF A COLLISION IN THE CENTRAFRICAN BELT

U-Pb on zircons and Sm-Nd on whole-rock analyses have been applied on the schists, micaschists and granulitic gneisses of the Yaounde series . The results fix the granulitic metamorphism in the Yaounde series at 620 +/- 10 Ma and the deposition of the series during the Upper Prote rozoic. In addition, another remnant of Lower Proterozoic basement, pr eviously recognized in northern Cameroon, has been identified at Kekem northwest of the Yaounde series. The Yaounde granulitic unit is re-in terpreted as the suture of a Pan-African collision between a passive m argin (Archean Congo craton and its Birrimian Nyong cover) to the sout h and an intensive granitized active margin (dismembered eburnian base ment and Upper Proterozoic series) to the north.