Timing of early to mid-cretaceous tectonic phases along North Africa: New insights from the Jeffara escarpment (Libya–Tunisia)

The Jeffara escarpment spans 400 km from southeastern Tunisia to sorthwestern Libya, and marks the northern edge of the Berkine–Ghadames Basin. Its horseshoe shape provides a good 3D control of regional-scale depositional architecture. Historically, the political border between Tunisia and Libya hindered the integration of studies over its entirety, which led to the establishment of separate litho-biostratigraphic frameworks. Field-work undertaken on both sides of the border has allowed the unification of lithostratigraphic schemes developed in both countries. Published stratigraphic ages of the different formations and members are compared and integrated in order to propose a unified bio-lithostratigraphic framework. The correlation of serial sections along the Jeffara escarpment shows that two major tectonic unconformities divide the Early Cretaceous sedimentary pattern. The first one is dated as Late Aptian and is commonly associated with the European “Austrian” tectonic phase. The second, which has previously not been recognized as a regional significant surface in Libya, occurs during the Middle Albian and marks moreover the transition from a siliciclastic to a carbonate-dominated sedimentation regime. These two important regional unconformities form the lower and upper boundaries of the Kiklah–Aïn el Guettar Formations, and can be associated with intra-plate deformation linked with the opening of the central segment of the South Atlantic and the Equatorial Atlantic oceans.