Pressure–temperature–time constraints on the Maghrebide mountain building: evidence from the Rif–Betic transect (Morocco, Spain), Algerian correlations, and geodynamic implications

The internal = northern zones of the Maghrebide belt includes allochthonous massifs that define, together with those from the Betics, Sicily and Calabria, a disrupted ‘Alkapeca’ terrane. In the Rif transect, taking advantage of new thermobarometric and geochronologic studies, we recognize a metamorphic complex with a mostly non-Alpine upper plate (Dorsale, Ghomarides–Malaguides), and a lower plate (Sebtides–Alpujarrides) affected by HP–LT, then HT–LP Alpine metamorphism. Some eastern Rif allochthons (Temsamane area) display MP metamorphism and could represent either Sebtide inliers or slivers from the African paleomargin. The Sebtide–Alpujarride late HT event also affects the bottom of the Ghomaride–Malaguide complex and can be related to the onset of the Alboran Sea rifting at ∼ 25 – 22   Ma , whereas their HP event is ascribed to an earlier ( ∼ 30 – 25   Ma ?), north- to northeast-dipping subduction event. A review of the Algerian literature allows us to infer a similar structure and evolution for the Kabylides. The Alkapeca disruption is classically explained by back-arc extension above the retreating subduction of the Ligurian–Maghrebian oceanic lithosphere. The question of whether the latter subduction followed an earlier and opposite Alpine–Betic (Nevado-Filabride) subduction or not, remains open to discussion. To cite this article: A. Michard et al., C. R. Geoscience 338 (2006).