Research-paper
New biostratigraphical data from the early Carboniferous sequences of the Adarouch area (NE Central Morocco)
Berkhli, Mostafa; Vachard, Daniel
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Abstract
The early Carboniferous sequences of the Adarouch area (NE Central Morocco) are subdivided into three sedimentological and biostratigraphical units: the first unit which belongs to the Late Viséan zones V3bß and V3bgamma was deposited on shallow carbonate platforms; the second unit belongs to the Late Viséan zone V3c and includes terrigenous deposits, such as turbidites, shales and olistostromes; the third unit belongs to the Serpukhovian stage and consists of sandstones and limestones. A new biostratigraphic analysis which is based on foraminifers, algae and "pseudoalgae" (aoujgaliids) allows an accurate dating of the units. The deposits of the zones V3bß and V3bgamma (first unit) contain characteristic calcareous microfossils, such as Stacheoides sp., Pseudoendothyra sp. and Ungdarella uralica. The V3c zone (second unit) is proven in two oolitic beds of the Mouarhaz and Akerchi formations, respectively, with Janichewskina sp. and Asteroarchaediscus sp. The Serpukhovian stage (third unit) is characterized by the disappearance of the alga Koninckopora and the appearance of the brachiopod Titanaria, as identified by DEDOK & HOLLARD (1980). The new data from the Adarouch area confirm the standard biostratigraphical scale of the Moroccan Meseta as established by VACHARD & BERKHLI (1992) and VACHARD & TAHIRI (1992).