‘Verrucano’ and ‘Pseudoverrucano’ in the Central–Western Mediterranean Alpine Chains: palaeogeographical evolution and geodynamic significance
V. Perrone, A. Martín-Algarra, S. Critelli, F. A. Decandia, M. D’Errico, A. Estevez, A. Iannace, A. Lazzarotto, M. Martín-Martín, I. Martín-Rojas, S. Mazzoli, A. Messina, G. Mongelli, S. Vitale, M. N. Zaghloul, 2006. "‘Verrucano’ and ‘Pseudoverrucano’ in the Central–Western Mediterranean Alpine Chains: palaeogeographical evolution and geodynamic significance", Tectonics of the Western Mediterranean and North Africa, G. Moratti, A. Chalouan
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The Anisian–Carnian Verrucano Group of the Tuscan Metamorphic Units and the Triassic–Hettangian Pseudoverrucano Formation of the homonymous unit are mainly continental redbeds occurring in Tuscany at the base of the Alpine orogenic cycle. A study carried out throughout the Apennine, Maghrebian and Betic Chains emphasized the presence in all these orogenic belts of deposits more or less coeval and similar both to the metamorphic Verrucano and to the unmetamorphosed Pseudoverrucano. Thus, the distinction of Verrucano and Pseudoverrucano successions has a palaeogeographical and geodynamic importance at the scale of the Western Mediterranean. Both successions developed during the continental rift stage of Pangaea, which led to later break-up at the edges of a future microplate, interposed between the Europe, Africa and Adria–Apulia plates, but they are characterized by different tectonometamorphic evolution. Pseudoverrucano-like deposits, devoid of Alpine metamorphism, characterize the highest tectonic units of the nappe stack and they overthrust units bearing Verrucano-like deposits. These latter show an Alpine tectonometamorphic history marked during the Miocene by intense deformation and HP/LT metamorphism (at pressures in the range of 0.8–2 GPa), followed by a retrograde phase associated with decompression, suggesting subduction and subsequent exhumation of continental crust. Intriguing palaeogeographical problems arise from the analysis of Verrucano-bearing units, because the same evolution seems to characterize both units considered to belong to a realm similar to that of the north-verging Austroalpine nappe system and some units referred to the south-verging fold-thrust belt derived from the Adria–Apulia palaeomargin.
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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.