Sedimentary Environment and Fluvial Trace Fossils of the Middle Jurassic in the Ait Ourir Basins, Western High Atlas, Morocco

The Middle Jurassic continental deposits in the Ait Ourir basins belong to the western High Atlas region of Morocco. More precisely, it is a part of the Northern Sub-Atlasic zone of the Marrakech High Atlas. These deposits, also known as “Couches Rouges,” overlie the last marine deposits. In this paper, we present an analysis of the sedimentological and ichnological analysis of the study area. A detailed description of the ichnofacies, facies, and recognition of architectural elements characteristic of the deposition environment reveals the evolution of a paleoenvironment, transitioning from an alluvial fan environment to a braided river system that becomes meandering. In the end, the system moved to a marginal-littoral environment characterized by fine to coarse deposits. The ichnological study aims to recognize the following Ichnogenera: Taenidium, Palaeophycus, Planolites and Arenicolites. These ichnogenera can be grouped into the continental Skolithos ichnofacies, Mermia and Scoyenia ichnofacies, typical of fluvial channel and Lake Margin deposits in semi-arid to arid regions.