HAVE WET AND DRY PRECAMBRIAN CRUST LARGELY GOVERNED CENOZOIC INTRAPLATE MAGMATISM FROM ARABIA TO EAST-AFRICA

To explain Cenozoic continental volcanism between Arabia and East Afri ca, the existing model infers that a plume impinged beneath Ethiopia, between 30 Ma and 20 Ma, and volcanism extruded within a 1000 km radiu s. Because relative motion of the Afro-Arabian plate was about northea st in the last 120 Ma, we infer that at 84 Ma a plume, originated from the core-mantle boundary, impinged beneath Nubia-Arabia and is now un der the Tanzania craton. This plume caused uplift (Afro-Arabian swell) and magma underplating. After Fyfe's idea (1992), the conceptual mode l proposed herein suggests that, following plume impact, there was in Nubia-Arabia only intrusion of mafic dykes because the crust was large ly unprocessed (wet). At about 50 Ma the plume was under Ethiopia, and coeval volcanism extruded because the crust was highly recycled (dry) . In Zaire-Burundi and Tanzania, volcanism is explained to be coeval w ith the arrival of the plume because there also the crust is recycled. In Arabia and Yemen-Ethiopia continental-flood basalts younger than 3 0 Ma formed because lithospheric extension along the Red Sea-Gulf of A den was the cause of (or the result of) plume(s), probably originated from the upper mantle.