Une plate-forme en distension, témoin de phases pré-accrétion téthysienne en Afrique du Nord pendant le Toarcien–Aalénien (synclinal Iguer Awragh–Afennourir, Moyen Atlas occidental, Maroc)

Abstract

Abstract A stratigraphic study and mapping allow defining the particular features of this area of the southwestern Middle Atlas (Morocco) during the Toarcian and the Aalenian. Numerous spectacular variations in thickness and facies are documented by the discovery of coralline build-ups dated to the Late Toarcian. They occur along the palaeostructures. Development of the structures occurred in several stages: (1) initial differentiation during the Early and Middle Toarcian; (2) homogenisation during the Late Toarcian, after the construction of the reefs. The Aalenian history is similar: differentiation (Early Aalenian)–homogenisation (Middle to Late Aalenian). Two palaeostructural trends are evident: SW–NE and transverse SSW–NNE to south–north. These caused separation of several subbasins, which alternatively deepened and shallowed, probably due to the tilting of several blocks to the southwest. To cite this article: F. El Hammichi et al., C. R. Geoscience 334 (2002) 1003–1010.