Late Cretaceous-Paleogene tectonic event in the Tunisian foreland basins: Insights from unconformities and basin inversion

Abstract

In this study, a comprehensive analysis was conducted on numerous sites within the Tunisian domains that exhibited early Atlasic inversion. The objective of this study is to evaluate and quantify this controversial compressive deformation period and conclude whether it is a local tectonic event or a regional compressional phase. Indeed, the geodynamic evolution of the Tunisian platform can be divided into major periods separated by a transitional period during the late Cretaceous. The first period was characterized by extensional movements associated with rifting phases that created several basins in a passive margin sedimentary environment. The second period was a compressive tectonic activity that occurred during the Cenozoic and resulted in major tectonic inversions.

This study examined ten distinct compressive structures, encompassing seismic line interpretation in the eastern Tunisian platforms, field outcrop maps and cross-sections, and the characterization of sedimentary hiatus. The results of the study demonstrated that during the Late Cretaceous-Eocene period, compressional structures were identified in the Golf of Hammamet, the Kairouan plains, the Golf of Gabes, and the central and meridional Atlas domains. These compressional structures have accumulated approximately 7.5 km of shortening and have exhibited a NE-SW decreasing deformation gradient from the Gulf of Hammamet to the Atlasic southern domain. Therefore, as a consequence of the cumulative shortening value, the large-scale sedimentary hiatus and the widespread deformation that was observed, it can be concluded that the Late Cretaceous-Eocene period corresponds to a confirmed compressional phase. This phase has inverted the sedimentary basins and triggered the creation of the Atlas orogen.