Aptian-Albian Diapirism and Compressional Tectonics Since Late Maastrichtian to Quaternary in Mateur-Tebourba Region (Northern Tunisian Atlas)

Abstract

New outcrop and seismic based tectono-stratigraphic observations of the es Sakkak-el Baouala Range in northern Tunisia provide a more sophisticated model of its structural evolution than previously possible. This model envisages two phases of contrasting structural deformation to explain the linear salt structures now observed in outcrop. Early extension triggered reactive and then active diapirism with salt reaching the surface during the Aptian. Diapiric structures formed at this time were subsequently buried by Albian-Early Maastrichtian sediments before undergoing further intermittent growth in the late Maastrichtian and Cenozoic in response to compression from the north. Thrusts assisted salt flowage to the surface in the early Paleocene was followed by erosion and reburial in the later Paleocene and Eocene. Growth synclines developed along the thrust foot-walls of salt cored structures. Jbel el Hallouf provides an excellent example of a flanking syncline formed during the Aquitanain-Tortonian, accommodating thick Miocene deposits while the es Sakkak salt cored anticline continued to rise on the thrust hanging-wall, until burial by upper Tortonian sediments. A further phase of folding and thrusting occurred during the late Miocene. This created significant topographic relief which was subsequently eroded and redeposited as conglomerates in the adjacent valleys. Compressional deformation continues to influence sedimentation into the Pliocene and later.