Ammonites and stratigraphic succession of the middle Toarcian – lowermost Aalenian from the Jebel Amergou (Moulay Bouchta area, Internal Prerif Zone, External Rif belt, northern Morocco)

Abstract

In the Rif Belt, the Toarcian–Aalenian outcrops are rare. The most important of these outcrops are those of the northern side of Jebel Amergou (70 km northwest of Fez). These outcrops, consisting of lumpy marlstones and marly limestones, are rich in ammonites. A section (JAM) located in a small ravine near Douar Amergou have been studied. Its stratigraphic series (20 m-thick), called the Amergou Formation, is divided into two members. The lower member yielded in the levels 3 and 4 a rich ammonite fauna from the middle Toarcian (Bifrons and Gradata zones) and some ammonites from the upper Toarcian (Bonarellii and Speciosum? zones); the upper member, divide into two levels, yielded in the level 2 rare ammonites from the lower Aalenian (Opalinum Zone). 44 species of ammonites have been identified, described and illustrated for the first time from the Toarcian–lower Aalenian succession of the Rif Belt. Most of these species are common to several basins of both, the northern and the southern margins of the Tethys and the NW European province.