Direct dating of brittle extensional deformation contemporaneous of Neogene exhumation of the internal zones of the Rif Chain

The brittle deformation of internal zones the Rif chain, corresponding to southern margin West Alboran Basin, is not or poorly dated because lack stratigraphic constraints. We provide for first time a direct dating in Ceuta peninsula located westernmost part Gibraltar arc. 40Ar/39Ar illite ages from fault gouges footwall and hanging wall Shear Zone range 11.9 ± 2.5 Ma 15.7 1.7 14.7 0.1 18.9 0.8 Ma, respectively. In addition, (UTh)/He apatite both units have been measured. They are younger hangingwall (~20–21 Ma) than (14–19 Ma), which highlights slightly different cooling histories. Thus, we interpret date growth authigenic (1M polytype) during exhumation through top few kilometers earth's surface. This study within chain reveals that an E-W directed extension occurred between ~18–15 low temperature Sebtide-Alpujárride units. From 15 11 direction shifted NNW-SSE only minor steep normal faults occurred. Brittle faulting stage slow (~1–2 °C/myr) starting at ~19 coeval with processes uppermost levels continental crust. These new data emphasize continuum extensional Burdigalian–Serravalian interval early phase then match well main subsidence pulses identified offshore neighboring Basin.