Four seismic Pre-Messinian units have been defined in the deep offshore.

The basal Pre-Messinian unit records an early Oligo-Miocene rifting phase.

The first post-rift unit (Langhian) is a transgressive deposit located to the south of the intra-arc basins.

The eastern Algerian basin opened as a transtensional rift system with normal and transcurrent faulting before collision between AlKaPeCa and Africa.

S-dipping thrusts and downward flexure of the basin evidence a Quaternary tectonic inversion.