On the origin and consequences of crustal-scale extension between Africa and Sicily since Late Miocene: insights from the Kaboudia area, western Pelagian Sea
Abstract
The eastern Tunisian shelf is located between the Gulf of Hammamet and the Gulf of Gabes and belongs to the Pelagian domain which underwent a continuous NE-directed extension and crustal thinning since Late Miocene. This geodynamic process induced the formation of NW striking normal faults and associated grabens both in the Tunisian Atlas and the Pelagian domain, including the Sicily Channel rifting zone (SCRZ). In this study, we combine regional stratigraphy from seismic reflection profiles, focal mechanisms, space geodetic measurements (GNSS) and thermal indicators from well data to propose a backward tectonic reconstitution of the Pelagian domain. The thinning of the continental crust is demonstrated by gravity inversion integrating published seismic refraction profiles. By completing the interpretation of tectono-stratigraphic records, we highlight a northeastward propagation of extension prevailing within the Pelagian shelf from Messinian to Plio-Quaternary times. We suggest that extensional tectonics is explained by (1) eastward slab tearing between the African continental lithosphere and the Tethyan oceanic slab, allowing asthenospheric upwelling, and (2) forces arising from relative motions between Nubia and the Hyblean-Malta block. The decoupling of these domains since Late Miocene likely results from a combination of the NW-directed plate convergence, inherited rheological contrasts within the continental crust, and weakening arising from mantle flow induced by the Tethyan slab rollback and tearing.