Pre-Existing Structures and Stress Evolution Controlling a Pull-Apart Basin in the Tunisian Atlas Domain (Siliana Area): Geodynamic Implication

In this paper we use a multidisciplinary approach including field observations, geological mapping and stress analysis to investigate the structural evolution of the NE-trending Sfina Basin, which located in the foreland basin of the Alpine chain (Maghrebides) in Tunisia. The Sfina Basin structure is the Neogene pull-apart basin, forming along the NE-trending Zaghouan fault, it located in Tunisian Atlas domain and formed in a NE‒SW-trending dextral strike-slip fault systems. Our result has shown that this NE-trending basin is limited in both northern and southern edges by two NE-trending dextral fault segments. During the Late Cretaceous‒Middle Miocene, under NE‒SW extensional regime, the NE-trending transtensional fault segments constituted the boundaries of the Sfina Basin that developed as a dextral releasing stepover. During the Late Miocene‒Early Quaternary, Sfina Basin was inverted under a regional NW‒SE-to-NNW‒SSE compressional event in response to the Africa‒Eurasia convergence with continental collision process. The inversion occurred mainly along Sfina Basin sidewalls by reactivation of the pre-existing NE‒SW-trending weaknesses as right-lateral transpressional shears and led to formation of the NE‒SW-trending major folds structures in the Sfina area.