The object of this paper is mainly the brittle tectonic analysis of the N12
0 degrees Bertat fault zone. Our investigations show that the Bertat fault
acted as a. dip-slip normal fault during the Triassic-Liassic submeridian e
xtensional episode. In Middle: Jurassic times, when the extensional trend w
as WNM-ESE to NW-SE, the Bertat fault acted as a transfer left-lateral stri
ke-slip fault. Finally, it was reactivated as a right-lateral strike-slip f
ault during the Cenozoic compressional phase which was oriented north-south
to NW-SE. ((C) Academie des sciences/Elsevier., Paris.).