Lithostratigraphic characterization of the Turonian in the San-Pedro Margin (Côte D’ivoire)

Abstract

The lithostratigraphic characterization consisted to highlighting, the lithologic, the thickness, mineralogical and petrographic nature of the different formations encountered during drilling in the Turonian stage of the wells in the study area. The data used consist of geological reports of five boreholes and LAS (Log Ascii Standard). This characterization reveals that the Turonian range consists of three major formations, namely claystones, of siltstones and sandstones interbedded with calcareous, dolomitic and silty formations. The clays are gray to black, tender to firm, subfissile and moderately hard to hard. Sandstones are very fine to very coarse, subangular to subarronded, well to poorly sorted, with silty, calcareous and often dolomitic matrix. Note the presence of pyrite, glauconite and carbonaceous debris. A lithostratigraphic correlation shows an increase in thickness of the sediments from east to west and from north to south. In the northeast clayey and silty sediments are dominant interbedded with rare limestone and scarce sandstone , while further west and south we notice a strong presence of sandstone, loose sand interbedded with claystone, siltstone and limestone. These characteristics are typical of deep and turbiditic environments.