Etude sedimentologique et palynologique des aquiferes du tertiaire des regions des lagunes (Abidjan) et du sud Comoe (Nouamou): Implication paleoenvironnementale/[Sedimentological and palynological study of the aquifers in the tertiary of the lagoons region (Abidjan) and South Comoe (Nouamou): paleoenvironmental implication]

The sedimentological and palynological study of 232 samples of cuttings from two servey drilled in the eastern Ivorian coastline allowed us to characterize the aquifers of early Miocene. It falls within the context of the national drinking water supply from aquifers of the sedimentary basin in the said areas. Sedimentation consists of two facies (the quartz sands and clays). The predominance of subrounded to shiny and rounded grains reflect an aquatic transport of a relatively more or less long journey. Quartz subrounded grains, yellow orange and foxed show the presence of an oxidation and the mats grains reflect a transport by the wind. The granulometry study shows a dominance of sigmoidal facies "S". Sand grains are coarse, medium and are well to poorly sorted with an asymmetry tends to thin elements. The sediments were entirely transported by saltation in more or less agitated dispositional environments. This is shown by the low calcium carbonate (CaC03) rate. The presence of glauconites, oxidized pyrites remains of bivalves in the sediments of Anoumabo show a deltaic environment while in Nouamou the depositional environment is of fluvial-deltaic type. The strong presence of spores and pollen grains are characteristics of the hot and humid climate and has also permitted to identify the early Miocene age in the wells.