CARACTERISATION LITHOSTRATIGRAPHIQUE DES SONDAGES ADIA 5 ET ADIA 6 D’ADIAKE : MIS EN EVIDENCE DES MOUVEMENTS EUSTATIQUES ET INFLUENCE DES GLAUCONITES SUR LES PROPRIETES PHYSIQUES DES SABLES

Abstract

The lithostratigraphic study of the drilling Adia 5 and Adia 6 permitted to understand the post-deposit evolution of the glauconites. This study permitted to show at Adiaké two eustatic movements that are the transgression and the regression. The transgression has been characterized by the presence of autochthonous glauconites and hard-ground and the regression by the presence of para-autochthonous and allochtonous glauconites. Also, this study shows that the glauconites alters themselves to form the kaolinite, the muscovite in small leaves, the iron oxides (hematite) and the iron hydroxides (goethite and limonite). Phenomena of exfoliations observe themselves on some allochtonous glauconites. The change of the glauconite to kaolinites and in ochers in the quartzous sands reduces their physical properties (framework, porosity and permeability). The presence of the ocher in the quartzous sands gives the ferruginous sandstone. The quartz of these sandstones are colored in brown and in yellow.