MICROFAUNAS, MICROFLORAS AND SUCCESSIVE P ALEOENVIRONMENTS FROM THE EL-MERS FORMATION BATHONIAN-QUESTIONABLE CALLAVIAN) IN THE SKOURA SYNCLINE (MIDDLE-ATLAS, MOROCCO)

In the Middle-Atlas (Morocco), the lower part of the ''Red beds'' (El Mers Formation), Middle Jurassic in age, contains various microfossils which permit to reconstruct the palaeoenvironmental evolution of this area for this period. Populations of abundant charophytes, collected at the base of the formation, are assigned to a new species : Porochar a hians FEIST & GRAMBAST-FESSARD. Species of ostracods are generally d ifferent than the European synchronous ones. The first ostracods appea ring at the base of the formation are monospecific and euryhaline (con tinental or brackish). They are more diversified above and correspond to a typical marine depositional environment.