In the Anti-Atlas, the Proterozoic-Paleozoic transition is one of the most complicated geological periods because it is accompanied by a considerable lack of paleontological and geochronological dating criteria. The Ediacaran period is the most interesting because it is supposed to record one of the major bio-events, the shift from microbial to metazoan-dominated ecosystems. It is represented by the volcanic to volcano-sedimentary Ouarzazate Group, covered by the sedimentary Tabia Member in the west. However, the relationship between these two provinces of contrasting volcanic-clastic deposition to the east and sedimentary deposition to the west is less clear. Most studies consider the Tabia Member to be a simple formation suspended at the base of the Cambrian, which was emplaced after a large depositional gap following the Ouarzazate Group. A sequential model proposed in the purpose of placing the different stratigraphic features in their spatio-temporal framework. This sequence model shows that the Tabia Member is not a Cambrian base series but a lateral substitution of the Ouarzazate Group. Consequently, the most complete succession of the Ouarzazate Group is represented by the filling of the Madaw basin, where the sedimentary hiatus supposed to separate the Ouarzazate Group and the early Cambrian does not exist.
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