Les séries du carbonifère inférieur de la région d'Adarouch, NE du Maroc central: lithologie et biostratigraphie

Abstract

The early Carboniferous series of the Adarouch area (northeast central Morocco) are subdivided into three sedimentological and biostratigraphical units. The first unit, which belongs to the Late Visean zones V3bβ and V3bγ, was deposited on shallow carbonate platforms. The second unit belongs to the Late Visean zone, V3c, and incudes terrigenous deposits, such as turbidites, shales and olistostromes. The third unit belongs to the Serpukhovian stage and consists of sandstones and limestones. A new biostratigraphical analysis, which is based on foraminiferal, algae and pseudoalgae, allows an accurate dating of the units. The deposits of the zones V3bβ and V3bγ contain characteristic calcareous microfossils, such as Stacheoides sp., Pseudoendothyra sp. and Ungdarella uralica. The V3c zone (300–400 m) is shown in two oolitic beds of the Mouarhaz and Akerchi Formations, respectively, with Janischewskina sp. and Asteroarchaediscus sp. The Serpukhovian stage is characterised by the disappearance of the algae Koninckopora and the appearance of the brachiopod Titanaria. The new data from the Adarouch area confirm the Moroccan biostratigraphical scale of the Moroccan meseta.