Stratigraphie et évolution structurale paléozoïque d'un segment de la Meseta orientale marocaine (Monts du Sud-Est d'Oujda): rôle des décrochements dans la formation de l'olistostrome intraviséen et le plutonisme tardi-hercynien

In the Paleozoic basement of the southeast Oujda mountains, the Lower Ordovician, Silurian-Devonian and Devonian-Dinantian are dated for the first time through palynology. This paper shows the autochtonous character and continuous stratigraphy of the formations of the Lower Ordovician to Devonian or probably Dinantian. The Intra-Visean Olistostrome is interpreted as a tectono-sedimentary breccia associated with strike-slip faults. The structural Variscan evolution is characterized by two major phases, each of them being divided in three stages. The ante-Upper Visean early phase is characterized in chronological order by (1) submeridian folds, (2) northeast-southwest folds and (3) extensional, oblique-slip, east-west trending faults. The second phase post-dates the Westphalian C and is marked by open east-northeast - west-southwest trending folds cut by reverse faults with the same trend and by a set of north-south sinistral and east-west dextral strike-slip faults. These later faults have allowed the emplacement of late Hercynian granitoïds.A palaeogeographical and structural reconstruction comparable to that established in the rest of the Moroccan Meseta is proposed.