Tectono-sedimentary evolution of the Southern Atlas front of Tunisia using integrated subsurface data: A case study of the Gantass structure

The Southern Atlas front of Tunisia (SAFT), which includes the Gantass structure, is part of the wide fold and thrust belt that developed along the North African margin. In the present work, an integrated geological and geophysical study has been conducted using geological maps, drillhole and seismic data to shed lights on the tectono-sedimentary evolution of the SAFT, with particular focus on the Gantass structure. Seismic data has been calibrated using well data and interpreted to reconstruct the pre-existing architecture of the region, revealing a Turonian carbonate platform to the south, which passes into a deep basin northwards. Notably, reef constructions have been identified along the platform margin. In addition, we reconstruct the main evolutionary stages of the region: (1) post-rift subsidence from Cenomanian to Campanian, following Early Jurassic rifting, (2) uplift of the Campanian-Maastrichtian carbonate platform during Late Cretaceous compression, (3) successive compressional phases marked by unconformities reflecting middle- to late Eocene, Tortonian and early Pleistocene periods. Our analysis demonstrates that the nucleation of the Gantass structure is not only controlled by pre-existing faults but also by stratigraphic heterogeneity. While most of the regional structures have been shaped by these successive tectonic phases, the Gantass structure, which we interpret as an incipient fault-propagation fold, developed during the latest compression stage. From an economic perspective, this study proves the presence of new reserves of phosphate deposits and highlights potential stratigraphic traps for future hydrocarbon exploration in the region.