The Rif belt (northern Morocco) is a mountain chain located at the junction between the Mediterranean and Central Atlantic Domains. Although the Rif belt underwent important Cenozoic (i.e., Alpine) shortening, remnants of the Mesozoic North African rifted margin are preserved in its external zones. This contribution aims to characterize the Mesozoic architecture and polyphase rifting history of this rifted margin. We present detailed field evidence and geochronological data from two palaeogeographic zones (Mesorif and Intrarif) preserving remnants of the former North African distal margin. The Mesorif conserves lithostratigraphic associations characterized by mafic intrusive rocks overlain by dismembered and discontinuous blocks of Lower Jurassic carbonates covered by Middle to Upper Jurassic sediments. U‐Pb zircon dating of four samples from this gabbroic complex shows ages close to the Triassic‐Jurassic boundary (195–200 Ma). The gabbros were emplaced within the continental crust at the end of the first Triassic rift event and exhumed shortly after during a second Middle Jurassic rift event, which presents exceptional rift‐related structures. The most distal part of the margin is exposed in the Intrarif. In this unit, the Beni‐Malek serpentinized peridotites exhibit ophicalcites with uppermost Jurassic limestones resting conformably on top, suggesting that exhumation of the mantle occurred at the distal part of the North African margin at this time. When integrated, these new evidences enable us to discuss the evolution of the western part of the North African rifted margin and its relations with the Moroccan Atlantic margin and Tethys system.
The Pinos terrane (Isle of Pines, W Cuba) is a coherent metamorphic complex that probably represents a portion of the continental margin of the Yucatan Block during the Mesozoic. Within the framework of other metamorphic terranes in the Greater Antilles, the Pinos terrane is characterized by the occurrence of high‐grade kyanite‐, sillimanite‐ and andalusite‐bearing metapelites and migmatites. Assessment and modelling of phase relations in these high grade rocks indicate that they reached a peak temperature of c. 750 °C at 11–12 kbar, and then underwent strong decompression to c. 3 kbar at c. 600 °C. Decompression was contemporaneous with the main synmetamorphic deformation in the area (D2), and was accompanied by segregation of trondhjemitic partial melts formed by wet melting of metapelites. Metamorphism terminated in the Uppermost Cretaceous (68 ± 2 Ma; 40Ar/39Ar dates on biotite and muscovite). The P–T–t‐deformation relations of the high‐grade rocks suggest that crustal thickening (during collision of this portion of the Yucatan margin with the Great Volcanic Arc of the Caribbean?) was followed by decompression interpreted to reflect exhumation by extension, possibly related to the initial development of the Yucatan Basin in the uppermost Cretaceous.
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