The Kimmeridgian-Tithonian boundary and age of the upper Jurassic formations of the Tunisian dorsale, comparisons with Algeria and Sicily

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 (Beni 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. (c) 2005 Elsevier SAS. Tous droits reserves.