The brittle deformation of internal zones of the Rif chain, corresponding to the southern margin of the West Alboran Basin, is not or poorly dated because of the lack of stratigraphic constraints. We provide for the first time a direct dating of brittle deformation of internal zones of the Rif chain, in the Ceuta peninsula located in the westernmost part of the Gibraltar arc. ⁴⁰Ar/³⁹Ar illite ages from fault gouges in the footwall and hanging wall of the Ceuta Shear Zone range from 11.9 ± 2.5 Ma to 15.7 ± 1.7 Ma and from 14.7 ± 0.1 Ma to 18.9 ± 0.8 Ma, respectively. In addition, (UTh)/He apatite ages from both units have been measured. They are younger in the hangingwall (~20–21 Ma) than in the footwall (14–19 Ma), which highlights slightly different cooling histories. Thus, we interpret the illite ages to date growth of authigenic illite (1M polytype) during exhumation through the top few kilometers of the earth's surface.

This study of brittle deformation within the internal zones of the Rif chain reveals that an E-W directed extension occurred between ~18–15 Ma during the low temperature exhumation of Sebtide-Alpujárride units. From 15 to 11 Ma, the direction of extension shifted to NNW-SSE and only minor steep normal faults occurred. Brittle normal faulting occurred during a stage of slow cooling (~1–2 °C/myr) starting at ~19 Ma and coeval with exhumation processes within the uppermost levels of the continental crust. These new data emphasize a continuum of extensional deformation during the Burdigalian–Serravalian interval with an early E-W directed phase and then a NNW-SSE directed phase that match well the main subsidence pulses identified offshore in the neighboring West Alboran Basin.

由于缺乏地层学约束，Rif链内部区域的脆性变形（与西阿尔伯兰盆地的南部边缘相对应）没有或年代不早。我们首次对位于直布罗陀弧线最西端的休达半岛的Rif链内部区域进行了脆性变形的直接测年。休达剪切带下盘和下盘断层泥中的⁴⁰ Ar / ³⁹ Ar伊利石年龄分别为11.9±2.5 Ma至15.7±1.7 Ma和14.7±0.1 Ma至18.9±0.8 Ma。另外，（U已经测量了两个单位的Th）/ He磷灰石年龄。它们在上盘壁（〜20-21 Ma）比下盘壁（14-19 Ma）年轻，这突出了冷却历史略有不同。因此，我们解释了迄今为止通过地表顶部几公里挖掘出的自生伊利石（1 M多型）的伊利石年龄。

这项对Rif链内部区域内的脆性变形的研究表明，在Sebtide-Alpujárride单元的低温掘尸过程中，E- W定向延伸发生在〜18-15 Ma之间。从15 Ma到11 Ma，延伸方向转向NNW-SSE，仅发生了较小的陡峭正断层。脆性正常断层发生在缓慢冷却阶段（〜1-2°C / myr），始于〜19 Ma，与陆壳最上层的发掘过程同时出现。这些新数据强调了在布尔迪加利－塞拉瓦利期期间的伸展变形的连续性，其早期为E- W定向阶段，然后为NNW-SSE定向阶段，与相邻西阿尔伯兰盆地近海发现的主要沉陷脉冲非常匹配。