Structure, paleogeographic inheritance, and deformation history of the southern Atlas foreland fold and thrust belt of Tunisia

Abstract

Structural analysis of the southern Tunisian Atlas was carried out using field observation, seismic interpretation, and cross section balancing. It shows a mix of thick‐skinned and thin‐skinned tectonics with lateral variations in regional structural geometry and amounts of shortening controlled by NW‐SE oblique ramps and tear faults. It confirms the role of the Late Triassic–Early Jurassic rifting inheritance in the structuring of the active foreland fold and thrust belt of the southern Tunisian Atlas, in particular in the development of NW‐SE oblique structures such as the Gafsa fault. The Late Triassic–Early Jurassic structural pattern is characterized by a family of first‐order NW‐SE trending normal faults dipping to the east and by second‐order E‐W trending normal faults limiting a complex system of grabens and horsts. These faults have been inverted during two contractional tectonic events. The first event occurred between the middle Turonian and the late Maastrichtian and can be correlated with the onset of the convergence between Africa and Eurasia. The second event corresponding to the principal shortening tectonic event in the southern Atlas started in the Serravalian‐Tortonian and is still active. During the Neogene, the southern Atlas foreland fold and thrust belt propagated on the evaporitic décollement level infilling the Late Triassic–Early Jurassic rift. The major Eocene “Atlas event,” described in hinterland domains and in eastern Tunisia, did not deform significantly the southern Tunisian Atlas, which corresponded in this period to a backbulge broad depozone.

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.…”

“…The late Cretaceous sequences are apparently unconformably overlain by the marine late Maastrichtian, Paleocene, and Eocene series (Zouaghi et al, 2011;Said et al, 2011b). …”

“…On a regional scale of Tunisian Atlas domain, the main potential décollement level determined from the mechanical stratigraphy is the Triassic-Jurassic sedimentary interface characterized by evaporites (Vially et al, 1994;Said et al, 2011b). In the study area, the …”

“…The deep geometry of the southern Atlas of Tunisia is still poorly constrained (e.g., Gabtni et al, 2011a;Said et al, 2011b). To constrain the geometry of the basement-cover interface and the structural style at depth, we used the well P3 drilled in the Saharan platform ( Figs.…”

A Geologically Consistent Permeability Model of Fractured Folded Carbonate Reservoirs: Lessons from Outcropping Analogue

“…This region is under NNW-SSE to N-S compression since the Aptian age (Bouaziz et al, 2002). Development of the Chotts range started in the Late Cretaceous, while folding of the other structures started in the Miocene (Saïd et al, 2011). Folding is still active today under a similar tectonic N-S regime (Gharbi et al, 2013).…”