The evolution of the oceanic Maghrebian Flysch Basin and its continuation in the Southern Apennines was studied by reconstructing mainly representative stratigraphic successions. In all sectors a common evolution has been identified. Rifting and drifting phases are indicated by remnants of oceanic crust, Jurassic limestones, Cretaceous–Palaeogene turbiditic and pelagic deposits. The pre‐orogenic sedimentation was mainly controlled by extensional tectonics and sea‐level changes. The occurrence of a generalized foredeep stage since the Early Miocene is testified by thick siliciclastic and volcaniclastic syn‐orogenic flysch successions. The deformation of the oceanic areas began in the Burdigalian and the resulting nappes were stacked in the growing chains. During the Middle Miocene, piggy‐back basins developed and the building of the chains was accomplished in the Late Tortonian. Areal distribution and ages of flysch deposits represent an important tool for the study of the diachronous growth of the accretionary wedges.

Terra Nova, 24, 34–41, 2012 Abstract The origin of the Numidian Formation (latest Oligocene to middle Miocene), characterized by ultra‐mature quartzose arenites with abundant well‐rounded frosted quartz grains, remains controversial. This formation, sedimented in the external domain of the Maghrebian Flysch Basin, displays three characteristic stratigraphic members with marked longitudinal (proximal–distal) and transverse (along‐chain) variations with palaeogeographical importance. The origin of the Numidian supply is related to the outward tectogenetic propagation when a forebulge evolved in the African foreland, leading to the erosion of African cratonic areas rich in quartzose arenites (Nubian Sandstone‐like). The ages of the Numidian Formation checked by Betic, Maghrebian and Southern Apennine data suggest a timing for the accretionary orogenic wedge, earlier in the Betic‐Rifian Arc (after middle Burdigalian), later in the Algerian‐Tunisian Tell (after late Burdigalian) and afterwards in Sicily and the Southern Apennines (after Langhian). A geodynamic evolutionary model for the central‐western Mediterranean is proposed.

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Abstract: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 carded 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 Verrucanobearing 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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