An Overview of the Eastern Atlas Fold and Thrust Belt and Its Foreland Basin Along the North–South Axis and Chorbane–Ktitir Platform: Surface/Subsurface Major Structures and Tectonic Evolution (North Africa)

Abstract

We present a structural overview of the major structures of the Eastern foreland basins of the Eastern Atlas and the N–S Axis, the Northern branch of the South Atlasic Front (SAF) and its relations with the Ktitir platform and Chorbane major structural anomaly. Different subsurface interpretations allow deciphering the major tectonic pulses in the Eastern Atlas and its foreland basin, from Jurassic–Early Cretaceous rifting to Upper Cretaceous–Late Eocene Atlas folding events well expressed in the surface and in the subsurface. Seismic interpretations allow visualizing the main control on the Triassic salt Diapirism related to deep-seated faulting affecting the Pre-Triasic and Meso-Cenozoic sedimentary sequences. Surface and subsurface interpretations show that the continuous reactivation of the deep-seated faults has trigged the lateral flow of the Triassic evaporites toward the salt diapirs. Furthermore, the salt material has played the role of a general décollement level of the post-Triassic cover during the shortening phases: Late Eocene Atlas phase and the Late Miocene–Quaternary Alpine phase. The Kairouan flexural basin, an intriguing subsiding zone at the front of the Atlas, coincides with a roughly E–W basin cutting orthogonally the N–S Axis and recording more than 8500 m of Meso-Cenozoic sedimentary sequence and recording the main Atlas tectonic pulses.