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Analyzes carried out on 262 cuttings samples from two boreholes located in the coastal sedimentary basin of Abidjan (south-west of the lagoon fault) were aimed at the paleoenvironmental determination of tertiary-age deposits. Indeed, these sedimentological analyses allowed the characterization of the lithological nature of the formations encountered by AB and BM drilling. They also helped to determine the origin of the sedimented material as well as the hydrodynamic conditions that governed the placement of the various deposits. Moreover, the deposits medium of the studied formations was revealed. The formations consist of an alternation of sands and sandy clays in the AB drilling and essentially glauconous clays for BM drilling. In the clay intervals, there is a weak presence of calcium carbonates on the whole of the two boreholes. The sands analyzed are of different granulometric grades (very coarse, coarse, medium and fine) according to the intervals. This, therefore, shows the different variations in the energy of the current that transported the sediment. From a facies point of view, the granulometric facies is dominant in the study area, indicating the variation in watercourse competence during sedimentation. Mostly sub-angular to sub-rounded quartz grains suggest a relatively distal proving source while their shiny blunted appearance evokes an aquatic environment. The sediments of these wells are therefore sands of fluviatile origin, deposited in a shallow marine environment.EuropeanScientific Journal June 2018 edition Vol.14, No.18 ISSN: 1857 -7881 (Print) e -ISSN 1857-7431 219Keywords: Paleoenvironment, hydrodynamic conditions, depositional environment, Abidjan RésuméDes analyses réalisées sur 262 échantillons de déblais issus de deux forages implantés sur le bassin sédimentaire côtier d'Abidjan (Sud-Ouest de « la faille des lagunes) avaient pour objectif la détermination paléoenvironnementale des dépôts d'âge tertiaire. En effet, ces analyses sédimentologiques ont permis la caractérisation de la nature lithologique des formations rencontrées par les forages AB et BM. Elles ont aussi contribué à déterminer l'origine du matériel sédimenté ainsi que les conditions hydrodynamiques ayant gouverné la mise en place des différents dépôts. Par ailleurs, le milieu de dépôts des formations étudiées a été révélé. Les formations sont constituées d'une alternance de sables et d'argiles sableuses dans le forage AB et essentiellement d'argiles glauconieuses pour le forage BM. Dans les intervalles argileux, il y a une présence peu marquée des carbonates de calcium sur l'ensemble des deux forages. Les sables analysés sont de différentes classes granulométriques (très grossières, grossières, moyennes et fines) selon les intervalles et témoignent des différentes variations de l'énergie du courant ayant assuré le transport des sédiments. Le faciès granulométrique de type hyperbolique est dominant dans la zone d'étude indiquant ainsi une variation de la compétence du cours d'eau pendant la sédimentation. Les grains ...

The material studied in this work comes from excavations of five hydraulic soundings in the localities of Fresco and Grand-Lahou located in the Southwest in the "onshore" part of the Ivorian sedimentary basin. These surveys are part of the national program for drinking water supply from aquifers. The lithological and sedimentological analyzes of the cuttings of these holes are carried out in order to identify the different lithological units crossed, to understand the sedimentary processes that have prevailed during the deposition of these sediments and to better characterize the

Maastrichtian to Ypresian-dated sediments from the 12 Frères borehole. (Fresco, southwestern Côte d'Ivoire), are here investigated for paleoenvironmental and paleogeographic significance. For this study, the preparation of palynological slides in the laboratory is done in three steps.: (1) sampling and physical treatment, (2) chemical attacks (HCl 10%, HF 40%) to dissolve the mineral matter and preserve the organic matter contained in the sediments, (3) mounting the collected organic matter between slide and coverslip for microscopic study. Quantitative analyses of dinoflagellate cysts and other palynomorphs have allowed reconstructions of paleoenvironments. Thus, from bottom to top, nine (9) depositional environments ranging from outer neritic to inner neritic via a lagoon or estuarine environment were determined. Following Lentin and Williams (1980), the deposits in the 12 Frères section are attributed to a tropical to subtropical province paleogeography.

Plusieurs pays africains ont adhéré au Réseau Africain de Géoparc (AGN) et ont entrepris de nombreuses études sur le géopatrimoine suite aux investigations menées par cette organisation pour promouvoir les richesses naturelles des pays africains. Les falaises de Fresco, premiers sites identifiés en Côte d’Ivoire, sont connues pour leurs richesses géologiques et écologiques. Ainsi, une étude bibliographique approfondie et complétée par l’analyse des données géologiques sur l’ensemble de ces affleurements ont permis de faire l’inventaire des éléments de valeur des falaises et de les évaluer sur le plan scientifique. L’évaluation de ces géosites (ensemble des cinq falaises) a livré une valeur moyenne de 0,7/1 et a ainsi confirmé leur importance en tant que géosites potentiels. L’environnement naturel aux alentours des falaises renferme une riche biodiversité de végétation littorale abritant de nombreuses espèces animales dont certaines sont en voie de disparition. Cette étude aura permis d’évaluer les falaises comme élément important de la géodiversité pouvant favoriser la promotion du géotourisme et contribuer au développement socio-économique de la région de Fresco. Several African countries have joined the African Geopark Network (AGN) and have undertaken numerous studies on geoheritage following the investigations carried out by this organization to promote the natural resources of African countries. The Fresco escarpments, the first site identified in Côte d’Ivoire, are known for their geologic and biologic wealth. Thus, an in-depth bibliographical study completed by the analysis of geological data made it possible to make an inventory of the elements of geodiversity of the five escarpments and to evaluate their scientific value. The evaluation of these geosites (all five cliffs) yielded an average of 0.7/1; and confirmed their importance as potential geosites. The natural environment around the cliffs contains a rich biodiversity of coastal vegetation, home to many animal species that some of them are endangered. This study will have made it possible to assess the cliffs as an important element of geodiversity that can allow the promotion of geotourism and contribute to the socio-economic development of the Fresco region.

Eboinda a fait l’objet de plusieurs campagnes de recherche scientifique et pétrolière depuis l’observation de suintements de bitume dans cette zone. La présente étude porte sur la caractérisation sédimentologique et paléoenvironementale de cette zone. L’objectif principal est de déterminer la nature lithologique et l’environnement de dépôt de ses sédiments. Ainsi treize (13) échantillons provenant de deux (2) puits d’hommes ont permis de caractériser les formations sédimentaires d’Eboinda. Au cours de ce travail plusieurs méthodes ont été utilisées pour réaliser les analyses lithologiques, granulométriques et morphoscopiques. Les analyses lithologiques ont mis en évidence une sédimentation dominée par des argiles sableuses avec des sables quartzeux et du bitume en faible proportion. La granulométrie a distingué trois (03) catégories de sables, allant de très grossiers, grossiers à moyens, tous provenant du domaine fluviatile donc continental transportés en majorité par charriage et par suspension. Les grains de quartz présents dans les sables sont subanguleux à subarrondis à aspect émoussé luisant (90%) ou rond-mats (10%). Les premiers indiquent que les grains ont subi un long transport en milieu fluviatile tandis que les seconds traduisent un transport éolien. Eboinda has been the subject of several scientific and oil research campaigns since the observation of bitumen seepage in this area. This study focuses on the sedimentological and paleoenvironmental characterization of this area. The main objective is to determine the lithological nature and the deposit environment of its sediments. Thus thirteen (13) samples from two manholes made it possible to characterize the area. During this work, several methods were used to carry out the lithological, grain size and morphoscopic analyses. Lithologic analyzes revealed a sedimentation dominated by sandy clays with quartz sands and bitumen in small proportion. The granulometry distinguished three (03) categories of sand, ranging from very coarse, coarse to medium, all coming from the fluvial domain, therefore continental, transported mainly by bedload and suspension. The quartz grains present in the sands are subangular to subrounded with a shiny blunt aspect (90%) or round-dull (10%). The first indicate that the grains underwent a long transport in a fluvial environment while the second reflect a wind transport.

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.