Sedimentological and Lithostratigraphic Study of Paleocene-Eocene of Foum El Kouss and lmiter, the Southern Flank of the Central High Atlas. Morocco

Abstract

This work concerns the outcrops of the Paleocene-Eocene series on the meridional side of the Central High Atlas, precisely in the localities of Boumalne-Imiter to the west of the Tinghir city. The main objective of this study is to propose a paleoenvironment and its evolution in time and space. To achieve this objective, we are interested in the lithological and microfacies description along the Imiter and Foum El-Kouss sections. From these two sections, three fundamental formations have been distinguished. From base to top, the Assaghmou and Jbel Guerssif formation (Upper Danian-Lower Thanetian) is dominated by mudstone to packstone limestone with few fragments of bivalves, and it is limited at the top by a maximum flooding surface with nautiloids, indicating an internal carbonate platform (Subdital). Above, the Jbel Talouite formation (Upper Thanetian–Lower Ypresian) is composed of an alternating succession of siltstones and red sandstones with bryozoans, as well as sedimentary figures explaining continental influences. This formation characterizes a continental environment that has undergone periodic marine invasions testified by carbonate passages oolitic grainstone. The whole series is topped by the Ait Ourithane formation (Ypresian) which is formed by marls and packstone to grainstone limestone with bryozoans, echinoderms and sometimes benthic foraminifera (Miliolide), indicating a medium deep and open marine environment (Intertidal to subtidal). According to these results, the lithological and microfacies variations allow us to propose that the paleoenvironmental context had a regime of progradation and retrogradation on a low sloping platform with a less developed barrier.