Analyse pétrosédimentaire des dépôts maastrichtiens et paléocène-yprésiens de la région de Kao et indices de minéralisations phosphatées (Région Tahoua, Niger Central)

This study concerns the south-central part of the lullemmeden intracratonic basin. The main objectives of the study were sedimentological analysis of the various facies and preliminary description of the nodules bearing phosphate mineralization in the Agougaran sector (Kao area, northern Ader Doutchi). The phosphate-bearing rocks are phospharudites. These occur as nodules of variable size and morphology. The phosphate nodules are hidden in the marl limestones or in attapulgite schists of the Barmou Member. Attapulgite schists contain the highest concentrations of nodules bearing phosphate mineralization. In the mineralized levels, nodules are either scattered or organized in layers or beds. The faunal association of the Barmou Member, which encases in the mineralized nodules, is made up of nautiluses, bivalves, sea urchins, gastropods, foraminifera and ostracods. This faunal association testifies to the emplacement of phosphate mineralization-bearing deposits in a confined marine environment.