Sur le granite orbiculaire de Tisselliline (Hoggar, Sahara central)

Abstract Orbicular granite outcrops in a small area near the northern edge of the Tisselliline granitic massif in the Ahaggar mountains (Algeria) in the central Sahara. Petrographic and chemical study leads to a double diffusion theory of its origin. Whereas orbicular rocks are generally found near a migmatite front, this particular example indicates that an orbicular facies can also be associated with small granite massifs, thus suggesting the possibility that a phase analogous to migmitization may be involved in the genesis of certain intrusive massifs of this type.