La limite Kimméridgien-Tithonien et l'âge des formations du Jurassique supérieur de la Dorsale tunisienne, comparaisons avec l'Algérie et la Sicile

The discovery of the Lowermost Tithonian Hybonotum-Lithographicum Zone allows for the first time to define the Kimmeridgian-Tithonian boundary in the pelagic and transitional facies (Béni Kleb Fm) of the Tunisian Dorsale and to divide within the formation the Kimmeridgian-lower Tithonian grey and/or pseudonodular mudstone and the massive Tithonian limestones. The Hybonotum-Lithographicum Zone was not identified in the reefal facies (Ressas Fm) and the Kimmeridgian and Tithonian are not divided. The Ressas Fm starts earlier, with the Upper Oxfordian, Bimammatum Zone. The Kimmeridgian-Tithonian of the Tunisian Dorsale is compared with the corresponding beds in Algeria and Sicily.