K-Ar and TL volcanism chronology of the southern ends of the Red Sea spreading in Afar since 300 ka.

Continental rift segments linked to the propagation of the Red Sea plate bo undary in Afar are dated using thermoluminescence and potassium-argon datin g techniques. These new results constrain the mechanism of the two moderate extensional structures located at the southern ends of the propagator: the Manda Hararo and the Dadar graben. Ages obtained show that their internal floor are about 30 and 100 kyr old, respectively, and that the deduced vert ical rate of fault scarps display values lower than those linked to the Gul f of Aden propagation. The lower deformation accommodated by the Red Sea st ructures, their youthfulness and the greater distance to the mature oceanic ridges could justify this contrast of evolution. (C) 2001 Academie des sci ences / Editions scientifiques et medicales Elsevier SAS.