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

Abstract

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.

Diapiric growth within an Early Jurassic rift basin: The Tazoult salt wall (central High Atlas, Morocco)

“…Across the Atlas Mountains, the description of diapirs has been hindered due to (i) the uneven distribution of Late Triassic evaporitic basins that has influenced the irregular development of diapiric structures and (ii) the difficult interpretation of such diapiric structures once tightened or even welded during the Alpine compression [e.g., Hlaiem, ; Bracene et al, ; Masrouhi and Koyi, ; Zouaghi et al, ]. In contrast, the Atlantic Atlas offshore Morocco shows a well‐documented distribution of diapiric structures formed along the slope of the passive margin with extensional diapirs in the upper slope and compressional diapirs in the lower slope [e.g., Hafid et al, ; Frizon de Lamotte et al, ; Tari and Jabour, ].…”

Style of Atlassic tectonic deformation and geodynamic evolution of the southern Tethyan margin, Tunisia

“…These structures are generally interpreted to be inherited from Triassic and Jurassic to middle Cretaceous rifting periods related with the opening of the southern Tethyan margin (Guiraud and Maurin, 1992;Kamoun et al, 2001;Piqué et al, 2002;Guiraud et al, 2005;Gharbi et al, 2013). Tethyan extensional structures of the southern Atlas of Tunisia have been reactivated in the late Cretaceous-early Paleocene Bracène and Frizon de Lamotte, 2002;Guiraud et al, 2005;Said et al, 2011b;Frizon de Lamotte et al, 2011;Masrouhi and Koyi, 2012;Masrouhi et al, 2013;Gharbi et al, 2013;Van Hinsbergen et al, 2014), middlelate Eocene (Atlassic compression; Bouaziz et al, 2002;Bracène and Frizon de Lamotte, M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 limestone and claystones. As well, Triassic and Jurassic sequences are locally exposed in Bouhedma and Hadifa structures but also recognized by exploration wells in the study area (Figs.…”

Recent spatial and temporal changes in the stress regime along the southern Tunisian Atlas front and the Gulf of Gabes: New insights from fault kinematics analysis and seismic profiles

“…The Atlassic compressional tectonic event is characterized by a WNW-ESE to NW-SE shortening. It caused the inversion of the major extensional Cretaceous structures in the Eocene Bracène and Frizon de Lamotte, 2002;Frizon de Lamotte et al, 2011;Masrouhi and Koyi, 2012;Gharbi et al, 2013;Masrouhi et al, 2013).…”