Interconnection salt diapir–allochthonous salt sheet in northern Tunisia: The Lansarine–Baoula case study

Abstract

Surface and subsurface data are used to illustrate the halokinetic style, structural evolution and kinematics of the Lansarine–Baouala salt structure in the Alpine domain of Tunisia. It corresponds to a salt structure showing a large salt canopy overhanging buried diapir. The salt structure is located along the main fault systems, inherited from the southern Tethyan passive margin periods. The Northern domain of Tunisia is undergoing diapirism, which has been recognized as active during the Upper Aptian and Lower Albian periods. Above the diapir apex, salt flows outward and spreads by gravity downslope. A minibasin has formed during this period of salt outward evacuation. The minibasin has a thickness practically correlated to the budget of salt evacuation toward the diapiric structure. During Cenozoic times, compressional deformation stages do not reflect active diapirism. The Lansarine–Baouala salt structure, consisting of connected salt sheets, was passively transported on the Southeast-verging major thrusts that are deeply rooted in the salt beneath the Mateur basin. The Northern Atlas of Tunisia reveals, as many others salt provinces, an interconnection of salt diapirs and significant laterally spreading allochthonous salt sheets (canopies?). In this domain, the inherited allochthonous Triassic salt sheets interlayered within recent series and connected to buried diapir have a significant role in the shallow structural complexity observed in the sedimentary cover during the subsequent contractional events.