LITHOSTRATIGRAPHIE ET SEDIMENTOLOGIE DES FORMATIONS SEDIMENTAIRES DE TIAPOUM, SUD-EST DE LA COTE D IVOIRE : IMPLICATION PALEOENVIRONNEMENTALE

Tiapoumdepartment is located in the southeast of the onshore basin of Cote dIvoire. The sedimentological, granulometric and morphoscopic analyzes carried out on 24 samples from two wells made it possible to determine the lithological, granulometric and paleoenvironmental evolution of the sediments of this area. The lithological characterization of the sediments revealed four lithological facies in the department of Tiapoum. We therefore have in the direction of sedimentation, a thick layer of clay-sandy, sands intercalated with ferruginous sandstone absent at Aby crossroads and the land of the bar which thins from upstream to downstream. As for the particle size analysis, it reveals that the sands of the department of Tiapoum were deposited by free accumulation. These are well to very well graded sands with a predominance of medium grains with an asymmetry towards the fine grains. They were deposited in a fluvial-type environment transported mainly by suspension and rolling and sometimes by saltation. Morphoscopy of the quartz grains revealed an abundance of sub-angular to sub-rounded grains with a shiny blunt appearance showing fractures or cracks due to shocks between the grains during transport. The sands of the department of Tiapoum therefore come mainly from distal environments and are transported by water. The environment that prevailed during the deposit of the Tiapoum department sediments is of the oxidized continental type and reworked in places.