UPPER CRETACEOUS OSTRACODES AND FORAMINIF ERA FROM THE EL KOUBBAT SYNCLINE, MIDDLE ATLAS, MOROCCO

The micropaleontological study of the Santonian to Maastrichtian forma tions from the Middle Atlasic El Koubbat syncline (Morocco) reveals be nthic and planctonic foraminifera and ostracodes. The microfaunal asso ciations allow us to join in the Upper Santonian the Formation of ''ma rry limestones of Santonian'', to suppose the presence of the Campania n in the Oued Item Formation, to confirm the presence of the Maastrich tian in the Fl Koubbat Formation, and to refer to the Maastrichtian ra ther than the Tertiary the lower part of the Irbzer Formation. The ''m arry limestones of Santonian'' are laid down on a distal platform, und er an important depth of water. The Oued Item Formation shows a decrea se of the bathymetry and the environments develop to a proximal platfo rm. With the Fl Koubbat Formation, appear episodically anoxic periods on the bottom, with particular conditions propitious to the developmen t of lonely taxons. In the lower part of the Irbzer Formation, infrali ttoral conditions are developed in a waved environment evolving into a paralic inner domain eventually subject to freshening. Species of ben thic foraminifera are known in other paleogeographic areas,in return, ostracod fauna is endemic in Santonian and Maastrichtian; the relation s with South Tethysian Margin and West African areas are rarefied. The systematic descriptions of different species of ostracodes are expose d and two new species are described.