B23 GEOCHEMISTRY OF ORGANIC MATTER IN THE UPPER TRIASSIC FACIES CENTRAL TUNISIA Unité de recherche « Géoressources Environnements naturels et Changements globaux » GEOGLOB code : 03/UR/10-02 1 Summary : Outcrop samples collected from Rheouis carbonates and shales in central Tunisia were analysed in order to evaluate their geochemical patterns. On the basis of biomarker maturity parameters (i.e. Ts/Tm 22S/(22S + 22R) of the C31 αβ-hopanes ratios 20S/(20R + 20S) and ββ/(ββ + αα) of C29 steranes…) this study suggest that the Carnian organic matter has already reached the stage of oil-generative window. This province could be a promising area