Submarine 'salt glacier' of Northern Tunisia, a case of Triassic salt mobility in North African Cretaceous passive margin

Stratigraphical, sedimentological and structural data and a Bouguer gravity map of Medjez-El-Bab (MEB) in Northern Tunisia are used to illustrate a Cretaceous example of salt extrusion on a passive continental margin. Located just south of the Teboursouk thrust front (a preferential décollement surface used by the continuous Tertiary shortening in this area), the MEB structure is a simple N40°E box anticline. Removing the two Tertiary foldings (Eocene and Miocene) leads to the exposure of the original feature of a simple submarine 'salt glacier'. The Triassic salt rocks appear as an Albian interstratified body between two Cretaceous series with stratigraphic normal polarity, suggesting a bedding parallel extrusion (at the sediment-water interface) of the Triassic salt in Cretaceous times. The formation of such salt extrusions are associated with extensional faulting (probably both in the cover and basement), the presence of a slope and basinwards salt flow. This scenario is similar to the allochthonous salt described in other salt provinces, characterizing passive margins.