Review of the deformation styles during the Cretaceous Tethyan period: inferred from slumps and fault Kinematics analysis along Northern Tunisia

International audienceIn northern Tunisia, the Cretaceous period is described as a spectacular episode of soft-sediment deformations exposed for several kilometers. These gravity-driven deformations are interpreted to be associated with the Tethyan passive margin rifting. Slump folds and fault kinematics are analyzed in order to characterize the structural style of Northern Tunisia basin' during the Cretaceous Tethyan period. As a result, Early Cretaceous sedimentation reflects a syn-rift stage mainly underlined by major basement faulting systems combined with other intra-basin growth normal faults. These faults are tilted northward creating a paleoslope (estimated here to be ± 3°) associated to abundant soft-sediment deformations. Major faults (probably listric) split the study area into various tectonic blocs. Meanwhile, the post-rift Coniacian-Maastrichtian rich-marly deposits seal all the inherited differentiations and were presumably driven by the isostatic response of various inherited major faults. Based on fault kinematic analysis, compressional events were not observed during the whole Cretaceous and the sedimentation mainly occurred under extensional tectonics during this period. Halokinetic movements and salt rise-up are active on the extensional structures essentially during the Mid-Cretaceous period allowing the creation of abundant large depocenters with numerous soft-sediment deformations. Thus, the Tunisian margin is described as an evaporite floored margin where significant part of the Mesozoic sedimentary cover underwent frequent gliding and spreading above the Triassic evaporite detachment layers, as described in several Atlantic-type passive margins. During the Cenozoic shortening, a fault inversion model is mainly accepted for the development of different thrust systems. Thus, a clear field relationship between various inherited structural entities and the present-day geographical repartition of faults and folds belts involves the role of the tectonic inheritance in style and the evolution of the northern Tunisia belt