Abstract:

The Algero-Tunisian confines (Tebessa region) belong to the southern Tethyan domain and the Monts Mellegue. This region is partly composed of Cenomano-Turonian carbonate outcrops; therefore, the investigated sections highlight the black shale levels reported over a short period, around the Cenomanian-Turonian boundary. The lithostratigraphic study designated a depositional environment that emphasized a relatively deep, calm, and often confined ocean environment significantly shallower on the northern part of the study area. The facies lithology and distribution leads  to underline the pelagic influences during the upper Cretaceous and neritic throughout the lower Cretaceous period. The maximum thickness of the Cenomano-Turonian (1000 m) was recorded in the southern zones and the minimum (100 m) occurred  further north. This palaeogeographic organization persists laterally in Tunisia as the extension of the Constantine mole. The geochemical analyses reveal that the maturity of the Cenomanian source rock is variable. Nevertheless, the Turonian source rock  seems to be at the beginning of the oil phase.