Laboratoire de Géologie, Ressources Minérales et Energétiques, UFR des Sciences de la Terre et des Ressources Minières (STRM), Université Félix Houphouët Boigny Cocody, 22 BP 801, Abidjan 22, Côte d'Ivoire
The analyzes carried out in this work relate to the biostratigraphy and paleotemperature, offshore geological formations of the Ivorian sedimentary basin. They are based on the study of 117 cuttings samples from the N1 and N2 wells. These analyzes led to a paleoenvironmental reconstruction. The main stratigraphic species of nannofossils allowed a local nannostratigraphic scale of the upper part of the Campanian and the late Maastrichtian and of the Maastrichtian Danian passage. In the different wells, the qualitative and quantitative analyzes show that at the Cretaceous / Paleogene limit, the nannofossil populations disappear with nearly 100% of their diversity and their overall numbers. However, we note that there was a slight warming in the Lower Maastrichtian followed by a cooling of the waters in the early Tertiary (Paleocene). The renewal of nannofossils does not begin until the Danian after the extinction resulting from the K / Pg crisis. In the wells, the sudden extinction (accompanied by a drop in CaCO3) and the mode of renewal of nannofossils indicate a catastrophic event at the end of the Cretaceous.
This work presents results of analysis of 3rd order sedimentary Megasequence of Cenomanian- Lower Senonian in two wells in Môyo block located on Abidjan margin in Côte d'Ivoire. It is based on the logging and sedimentological data supported by few biostratigraphic data. This analysis helped to discriminate systems tracts of lowstand systems tracts, Transgressive systems tracts and Highstand systems tracts in the depositional megasequence. The lithology of this Megasequence consists of interbedded sandstone and sand within clay formation. Lowstand Systems Tracts are rich in sand and sandstone and accumulated in an environment extending from coast to mid-continental shelf.
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
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