Geodynamic evolution of the Tunisian margin during Albian-Cenomanian period; structural evidences of the Austrian Phase and the precocious tectonic inversion of the Tunisian Atlas

The Zebbag and Fahdene Formations outcrop on-shore Tunisia and provide an excellent opportunity to test models for the tectono-sedimentary evolution of this region during the Albian-Cenomanian. In this contribution, a NW-SE compressive stress regime resulted in shortening of the Tunisian margin and this compressional tectonism defines the Austrian phase described in the surrounding margins. This event is not widely documented but evidence provided by NE-SW thrusting and folding, that resulted in an angular unconformity, active halokinetic diapirs and transpressional NW-SE pull apart basins confirm our findings, suggesting regionally extensive tectonism. The observed compressional deformation can be considered as a precursor to the Alpine Orogeny causing an important and general inversion of the paleoblocks inherited from the Tethyan Jurassic and Lower Cretaceous rifting. A late Albian-Cenomanian onset of compressional deformation along the Tunisian margin may be intimately related to the drift of Africa with respect to Europe and to the opening of Atlantic Ocean.