Sedimentological analyses of the Upper Cretaceous and Lower Eocene carbonate successions in the Mateur–Beja area (NW of Tunisia): effects of tectonic regime on sedimentation

Abstract

Abstract The northwestern Tunisian Mateur–Beja domain comprises a thick succession of carbonate units belonging to the Late Cretaceous (Abiod Formation) and the Early Eocene times (Bou Dabbous Formation and its lateral equivalent). Sedimentological analyses were carried out on these sedimentary units with regard to their paleogeographic reconstructions. Three sections from the Upper Cretaceous and ten sections from the Lower Eocene successions were selected and correlated through the study area. The Upper Cretaceous Abiod Formation is composed of foraminiferal biomicrite limestones and marls deposited in outer platform to basin environments located slightly below storm wave base. The Lower Eocene carbonate successions are characterized by various storm-induced coarse- and fine-grained facies deposited in inner platform to basinal environments. Both carbonate units are characterized by significant lateral variations in thickness and facies. Close inspections show that thickness and facies variations were especially caused by synsedimentary major fault activity and locally by halokinetic movements. Comparison between the two studied units suggests that the changes of tectonic regime would have had significant impacts on thickness and facies distribution. Thus, the Upper Cretaceous and Lower Eocene carbonate deposits are interpreted in tectonically controlled basins.