Abstract
The present-day tectonic setting of the Western Mediterranean region, from the Pyrénées to the Betics and from the Alps to the Atlas, results from a complex 3-D geodynamic evolution involving the interactions between the Africa, Eurasia and Iberia plates and asthenospheric mantle dynamics underneath. In this paper, we review the main tectonic events recorded in this region since the Early Cretaceous and discuss the respective effects of far-field and near-field contributions, in order to unravel the origin of forces controlling crustal deformation. The respective contributions of mantle-scale, plate-scale and local processes in the succession of tectonic stages are discussed. Three periods can be distinguished: (1) the first period (Tethyan Tectonics), from 110 to 35 Ma, spans the main evolution of the Pyrenean orogen and the early evolution of the Betics, from rifting to maximum shortening. The rifting between Iberia and Europe and the subsequent progressive formation of new compressional plate boundaries in the Pyrénées and the Betics, as well as the compression recorded all the way to the North Sea, are placed in the large-scale framework of the African and Eurasian plates carried by large-scale mantle convection; (2) the second period (Mediterranean Tectonics), from 32 to 8 Ma, corresponds to a first-order change in subduction dynamics. It is most typically Mediterranean with a dominant contribution of slab retreat and associated mantle flow in crustal deformation. Mountain building and back-arc basin opening are controlled by retreating and tearing slabs and associated mantle flow at depth. The 3-D interactions between the different pieces of retreating slabs are complex and the crust accommodates the mantle flow underneath in various ways, including the formation of metamorphic core complexes and transfer fault zones; (3) the third period (Late-Mediterranean Tectonics) runs from 8 Ma to the Present. It corresponds to a new drastic change in the tectonic regime characterized by the resumption of N-S compression along the southern plate boundary and a propagation of compression toward the north. The respective effects of stress transmission through the lithospheric stress-guide and lithosphere-asthenosphere interactions are discussed throughout this period.
Highlights
Résumé – Évolution géodynamique d’une limite de plaque diffuse en Méditerranée occidentale, interactions à courte et longue distance
This review shows the evolution of the geodynamic framework of the Western Mediterranean since the Early Cretaceous and the respective contributions of local and distant forces
This period is further divided in Tethyan I, Tethyan II and Tethyan III. (ii) Mediterranean Tectonics (35–8 Ma) when all deformations are under the control of slab retreat and (iii) Late-Mediterranean Tectonics (8–0 Ma) when slab retreat progressively stops and the situation return to the Tethyan stage with stress transmission across the whole plate boundary zone, from Africa to Europe, and large-scale mantle convection is again the main driver
Summary
The Mediterranean mountain belts and post-Eocene back-arc basins result in fine from the convergence of Africa and Eurasia (Dercourt et al, 1986; Ricou et al, 1986; van Hinsbergen et al, 2019). This region has been studied in great detail since more than a century and its tectonic history has been reconstructed since the Triassic (Dercourt et al, 1986, 1993; Ziegler, 1999; van Hinsbergen et al, 2019; Angrand et al, 2020). We review in this paper the recent findings with a special attention to the outcome of the Orogen Project and discuss their implications on the various drivers, near-field and far-field, of the orogens and basins of the Western Mediterranean
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