Article
French
ID: <
10.3406/geolm.2001.1717>
·
DOI: <
10.3406/geolm.2001.1717>
Abstract
Petrology and the structure of Paleoproterozoic metamorphic series In the Zenaga inlier (Anti-Atlas, Morocco). The Paleoproterozoic metamorphic series of the Zenaga inlier constitutes the enclosing of Ebournian granites. It's a monotonous series oriented E-W to NE-SW, mainly composed of amphibolites, schist, and garnet-sillimanit micaschist. The geochemical and petrography study shows that the amphibolites evolved from old volcanic layers, basaltic in nature, and the schist and micaschist came probably from a turbiditic set, formed by a succession of metashales and metagrauwackes with a predominance of the latter. The structural analysis proves at least three phases of deformation : D1 phase is related to the Ebournian orogeny, while D2 phase, which presents a heterogenous non coaxial strain pattern, and D3 phase which shows a crenulation cleavage, are linked to the Pan african orogeny. The first metamorphic pangenesis associated to SI schistosity is a mesosonal pangenesis of an amphibolite iacies. The main paragene-sis in association with S2 reveals an episonal retrograde metamor-phism in the green schist fades. Pressure and temperature are esti-med at P = 2 to 2,5 Kb and T = 450° C.