Neoproterozoic belts in the Moroccan Anti-Atlas area

Abstract

Abstract : Field Works in the Anti-Atlas Precambrian inliers located in the southern part of the “Anti-Atlas major fault” (Ifni to Bou–Azzer inliers), allow us to make a hypothesis on the northward extension of the Souttoufide belt (Northern part of the Mauritanide belt) to the West of the Anti-Atlas. In this hypothesis, two Late Neoproterozoic belts should be considered in the Anti-Atlas area: a northern belt with a SE-NW direction extended from Bou-Azzer to the western part of the High Atlas and Western belt with a meridian direction involving the Bas Draa, Ifni and Kerdous inliers.
Three main parameters have been taken in consideration: 1)-the northern Neoproterozoic calc-alkaline intrusions in the northern belt are related to a northward dipping slab (supported by gravimetric models) while the Ediacaran volcanic intrusions are related to a post tectonic stage; 2)- the Late Neoproterozoic magmatism and volcanic intrusions from the western inliers can also be linked to a “subduction zone” which is necessarily different from the “Bou-Azzer–Siroua” subduction zone; 3)-stratigraphic correlations between the Bou-Azzer and the western inliers (Kerdous and Ifni) indicate that Ediacaran formations (Ouarzazate group) are undeformed in the eastern inliers (Bou Azzer and Irghem) and schistosed (S3) in the western inliers (Kerdous and Ifni).
So, we are supporting the existence of two orthogonal Neoproterozoic belts taking into account the cross-cutting of the “Anti-Atlaside belt” (Bouazzerides?) by the “Souttoufide belt” (linked to the Cadomian orogen).
Several paleogeographic schemes will be presented to enhance this hypothesis.