Structures Sédimentaires et Ichnofossiles des Formations du Crétacé Supérieur Sommital et du Tertiaire du Bassin Sud-Ouest de la Côte d’Ivoire : Intérêt Paléoenvironnemental

Abstract

Cliffs of Fresco located southwestern part of ivorian coastal basin are subjet of this study. Lithostratigraphy of upper Cretaceous and Tertiary series were reviewed from the five (5) surveyed, described and daded. This aimed to define the dynamics of an environment (at a time), based on identification and interpretation of sedimentary figures and ichnofossils. A proposed synthesis description allowed to deduce paleoenvironmental interest of analyzed deposits. 44 samples taken from the five (5) cliffs sections upported this study. The lithology indicates a dominant clay and sand sedimentation with intercalations of sandstone and glaucanious and phosphated limestone. Sedimentary structures described are of various types. These figures appear as forms built by a fluid flow action, produced by asymmetrical wrinkles and dunes. They result from mass transport (slumping, casting) and turbidity flow; The stratifications are various shapes : intertwined, fishbone and tabular, dish structures, flasers and lenticulars beddings. Deformation imprints produced after deposition and before consolidation have been identified by load figures, sedimentary structures are good stratigraphic criteria and good indicators of the direction of flow. These ichnofossils are post-depositional event and occur in a variety of environments, from continental to marine. They are generally associated with coastal margins and shallow marine environments.