New sedimentological studies and sequence stratigraphic framework of the Turonian deposits, in Tunisia, were conducted to facilitate the reading of the local stratigraphic nomenclature by comparing it with the global stratigraphic data. A new sequence stratigraphic subdivision of the Turonian interval has been proposed, based on the lithological and paleontological characteristics from Berda, Chemsi, Orbata and Belkhir sections (Gafsa area).

A detailed sedimentological investigation of the Bireno carbonates, correlated later on with other sections (northern Chotts, Sidi Bouzid, and Kasserine areas), has allowed to recognize three facies associations. They are distributed along a ramp system, evolving from proximal to distal domain and highlighting a northward deepening, well evidenced by isopach and paleogeographic maps.

Four 3rd order sequences (S-1 to S-4) have been identified; they correspond to the Bahloul Formation (lowest Turonian), the Gattar and Annaba Members (lower Turonian), the Bireno Member (lower Turonian to upper Turonian), and the Lower Aleg Member (uppermost Turonian). The most transgressive intervals correspond to the Bahloul Formation (mfs1), the Annaba Member (mfs2) and the upper B2 unit (mfs3).

The regressive ones correspond to the Gattar member, B1, B3 and B4 units. This subdivision has allowed the tracing of reasonable timelines and the correlation of the Tunisian Turonian deposits with their analogues in the southern Tethyan margin.

This study will significantly help to improve the conception of stratigraphic architecture and the depositional morphology at the scale of the southern Tethyan margin.