Mauretanian flysch nappe in the northwestern Rif Cordillera (Morocco): deformation chronology and evidence for a complex nappe emplacement
A. Chalouan, A. El Mrihi, Kh. El Kadiri, A. Bahmad, F. Salhi, R. Hlila, 2006. "Mauretanian flysch nappe in the northwestern Rif Cordillera (Morocco): deformation chronology and evidence for a complex nappe emplacement", Tectonics of the Western Mediterranean and North Africa, G. Moratti, A. Chalouan
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This study deals with the Mauretanian flysch nappe in the southern side of the Gibraltar Strait, NW of the Rif belt (Morocco), where it is possible to better appraise the stacking pattern of its two structural components (the Tisirene and Béni Ider nappes), and to decipher the chronology of deformation and its structural relationships with the overlying (Predorsalian and Numidian nappes) and the underlying nappes (Melloussa and Intrarif units). It is found that the main deformations were produced by an intermittent compressional regime, during which north-south- to NW-SE-directed compressional phases alternated with ENE-WSW to east-west-directed compressional ones. Whereas the former were generated by the Africa–Iberia convergence and resulted in small-scale thrusts and a brittle deformation style, the latter were driven by the west-drifting Alboran plate and resulted in paroxysmal fold–thrust deformations. Field evidence shows that the emplacement of the Mauretanian nappe over the Massylian one and the Intrarif units operated by interrelated compressional and gravitational processes, by virtue of which the majority of nappes stacked in an out-of-sequence regime. The precise age of the paroxysmal phases remains uncertain because of paucity or absence of direct stratigraphical data. However, this structural evolution is likely to have started as early as the mid-Burdigalian, when sedimentation synchronously ceased in the flysch trough. Its final phases may be placed precisely between the Langhian (N8) age of the most recent formations overlapped by these nappes and the late Tortonian age of the oldest formations transgressively covering them.
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This book provides an insight into the overall tectonic evolution of the Western Mediterranean region and North Africa. The tectonic setting of the region reflects a long-lived and complex evolution, mainly related to the Alpine Orogeny. This inheritance is expressed by an intricate pattern of arc-shaped mountain chains, the Alps, the Betic–Rif Cordilleras and the Apennine–Maghrebian belt, whose southern branches mark the present limit between the African and Eurasian plates. The volume covers the Maghrebian chains in North Africa, from Tunisia to Morocco and the Western and Central Mediterranean, from Spain to Italy from the pre-orogeric phases (Palaeozoic–Mesozoic) to the post-collisional neotectonic and Quaternary development. It includes both original research papers and syntheses dealing with the aspects of structural, sedimentary, metamorphic and marine geology.