NEW DATA ON THE STRATIGRAPHY OF CARBONIFE ROUS TERRAIN OF THE EASTERNMOROCCAN MESETA (DEPRESSIONS IN DEBDOU, MEKAM AND JERADA)

Lower Carboniferous deposits from Eastern Morocco are located in small depressions within a more or less mountainous Jurassic area. Sections from Tafechna, Flouch and Oued Korima (Debdou and Mekam basins, Easte rn Morocco) are accurately described. Owing to detailed field examinat ion, misinterpreted lithological aspects are corrected, i.e. volcano-s edimentary deposits are very important and carbonate deposits almost a bsent. Debdou yields alternations of blackish shales and sandstones wi th intercalations of tuffites overlain by volcanoclastic or calcareous sandstones, whose turbiditic origin is indicated by graded-bedding an d scour casts, and also by reworked oolites and Foraminifera. Mekam sh ows slumped limestones and conglomerates with basement pebbles, cement ed by carbonates, and with some reworked Foraminifera, overlain by alt ernations of greenish shales, tuffaceous siltstones and ashes. The str atigraphical background of these sections is also explicited or modifi ed. Existence of Tournaisian beds is excluded. Assemblages of Foramini fera are always uppermost Visean or lowermost Serpukhovian in age. New palynological data agree with this fact; so do former Goniatites dati ngs. These series are paralleled with the well-known series of the are a: Jerada, Tazekka, ''Northern Olistostrome'' (including Jorf Ouazzene , Zekkara and Tannecherfi outcrops). These comparisons concern at the same time the biostratigraphy, the environments, the volcanism, etc. T he Uppermost Visean V3c stratigraphy of Jerada is established as well as the Serpukhovian E1-E2 stratigraphy from Tazekka and Northern olist ostrome, where V3c remains are reworked. Importance of Brigantian (V3c ) substage is emphasized at the regional scale, it is the maximal tran sgression time upon the Devonian epimetamorphic substrate; transgressi on probably begun in the Upper Asbian (V3bgamma). Knowledge of Serpukh ovian (= Namurian A) within the various basins needs new investigation s. This stage is still characterized locally by a volcanic activity an d important tectono-sedimentary movements. Other periods of Namurian-W estphalian are only known at present within the Jerada basin. Accurate datings, especially during the V3c, prove the diversity of paleoenvir onments and their close juxtaposition: volcanoes, marshes, hills, carb onate platforms, paleocanyons, etc. This landscape seems to be divided into compartments by N30 and N70 faults producing horst and graben st ructures, which could also be strike-slip faults.