Tectonic controls on Late Cretaceous sedimentation on the southern Tethyan passive margin, Tunisia: new evidence of structural segmentation and early basin inversion.

Late Cretaceous lateral facies and thickness changes are common in the southern Tethyan margin, especially during the final rifting stages of the Tethys and its early onset of closure. Particularly, northern Tunisia, being located closure to a plate boundary, represents an important area to investigate the tectonic influence on sedimentation. In this paper, detailed sedimentological, biostratigraphical and tectonic studies carried out in north-central Tunisia (Serj-Bargou area) to provide more data and precisions on the lithostratigraphy framework and tectonic control on Late Cretaceous deposits. Investigation of field data, high-resolution biostratigraphy, gravity data analysis and lithostratigraphic correlations of strata deposited during the Late Cretaceous allowed us to precisely determine the timing of unconformities and constrain the history of the subsidence inversion of the basin. Three major unconformities have been identified in the SW of Jebel Bargou and span the period from Coniacian to Maastrichtian. These unconformities are marked by Paleocene marls (containing the G. trinidadensis biozone) that unconformably overlie the Late Coniacian series (containing the D. concavata biozone), indicating an early tectonic compressional event in the Late Cretaceous, that probably started in Turonian. Similar tectonic inversion events have already been identified in other Tunisia areas and in the surrounding regional context within the northern and southern Tethyan margin during the Late Cretaceous. This inversion could be explained by a Santonian compressional event, which might have started earlier, in the context of the convergence between African and European plates. The inversion is reflected stratigraphically across the African margin and the intraplate basins, such as the Serj Bargou basin, by a highly reduced accommodation space and unconformities. This tectonic inversion indicates the effects of the change in the poles of rotation related to the opening of the Atlantic at about 83–85 Ma on the former North African passive margin. [ABSTRACT FROM AUTHOR]