Alpine plate kinematics in the western Mediterranean: a westward-directed subduction regime followed by slab roll-back and slab detachment

Abstract

Abstract Integration of a wide range of multidisciplinary data, including seismic tomography features, regional tectonic transport directions and ages of subduction/collision, lithospheric extension and slab detachment, suggests a new model for the development of the Alpine belt in the western Mediterranean. The model implies that the backbone of the Alpine Orogeny was formed by a composite SW-NE-striking subduction system, active until some time before 22 Ma. The system which consumed Mesozoic Tethyan lithosphere was dipping westward under the leading edge of Iberia which was drifting eastward with respect to North America under the influence of the opening of the North Atlantic. Allowing for a series of late-stage extensional regimes, with local formation of Neogene oceanic lithosphere, in the Valencia Gulf, Provençal-Algerian basin and southern Tyrrhenian basin, and inherent slab roll-back, the original collision belt may be reconstructed comprising all present Alpine metamorphic core complexes in the western Mediterranean: Betic-Rif, Kabylies and the Sicily-Apennines(-Corsica) belt. It follows that in the western Mediterranean the northward drift of Africa against Iberia/Europe, although influential, e.g., in creating the E-W grain of the Betic Cordilleras, has not been the controlling factor. In contrast, in the eastern Mediterranean the influence of N-S convergence has been much more pronounced due to the hinged sinistral movement of the African plate. A major part of the Europe-Africa N-S convergence was accommodated in a coherent N-dipping subduction zone running from North Africa through Sicily-Calabria to Crete, becoming increasingly significant to the east.