The western Mediterranean subduction zone (WMSZ) extends from the northern Apennine to southern Spain and turns around forming the narrow and tight Calabrian and Gibraltar Arcs. The evolution of the WMSZ is characterized by a first phase of orogenic wedging followed, from 30 Ma on, by trench retreat and back‐arc extension. Combining new and previous geological data, new tomographic images of the western Mediterranean mantle, and plate kinematics, we describe the evolution of the WMSZ during the last 35 Myr. Our reconstruction shows that the two arcs form by fragmentation of the 1500 km long WMSZ in small, narrow slabs. Once formed, these two narrow slabs retreat outward, producing back‐arc extension and large scale rotation of the flanks, shaping the arcs. The Gibraltar Arc first formed during the middle Miocene, while the Calabrian Arc formed later, during the late Miocene‐Pliocene. Despite the different paleogeographic settings, the mechanism of rupture and backward migration of the narrow slabs presents similarities on both sides of the western Mediterranean, suggesting that the slab deformation is also driven by lateral mantle flow that is particularly efficient in a restricted (upper mantle) style of mantle convection.

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The Mediterranean offers a unique opportunity to study the driving forces of tectonic deformation within a complex mobile belt. Lithospheric dynamics are affected by slab rollback and collision of two large, slowly moving plates, forcing fragments of continental and oceanic lithosphere to interact. This paper reviews the rich and growing set of constraints from geological reconstructions, geodetic data, and crustal and upper mantle heterogeneity imaged by structural seismology. We proceed to discuss a conceptual and quantitative framework for the causes of surface deformation. Exploring existing and newly developed tectonic and numerical geodynamic models, we illustrate the role of mantle convection on surface geology. A coherent picture emerges which can be outlined by two, almost symmetric, upper mantle convection cells. The downwellings are found in the center of the Mediterranean and are associated with the descent of the Tyrrhenian and the Hellenic slabs. During plate convergence, these slabs migrated backward with respect to the Eurasian upper plate, inducing a return flow of the asthenosphere from the back-arc regions toward the subduction zones. This flow can be found at large distance from the subduction zones and is at present expressed in two upwellings beneath Anatolia and eastern Iberia. This convection system provides an explanation for the general pattern of seismic anisotropy in the Mediterranean, first-order Anatolia, and Adria microplate kinematics and may contribute to the high elevation of scarcely deformed areas such as Anatolia and eastern Iberia. More generally, the Mediterranean is an illustration of how upper mantle, small-scale convection leads to intraplate deformation and complex plate boundary reconfiguration at the westernmost terminus of the Tethyan collision.

Summary Geological and geophysical constraints to reconstruct the evolution of the Central Mediterranean subduction zone are presented. Geological observations such as upper plate stratigraphy, HP–LT metamorphic assemblages, foredeep/trench stratigraphy, arc volcanism and the back‐arc extension process are used to define the infant stage of the subduction zone and its latest, back‐arc phase. Based on this data set, the time dependence of the amount of subducted material in comparison with the tomographic images of the upper mantle along two cross‐sections from the northern Apennines and from Calabria to the Gulf of Lyon can be derived. Further, the reconstruction is used to unravel the main evolutionary trends of the subduction process. Results of this analysis indicate that (1) subduction in the Central Mediterranean is as old as 80 Myr, (2) the slab descended slowly into the mantle during the first 20–30 Myr (subduction speeds were probably less than 1 cm year− 1), (3) subduction accelerated afterwards, producing arc volcanism and back‐arc extension and (4) the slab reached the 660 km transition zone after 60–70 Myr. This time‐dependent scenario, where a slow initiation is followed by a roughly exponential increase in the subduction speed, can be modelled by equating the viscous dissipation per unit length due to the bending of oceanic lithosphere to the rate of change of potential energy by slab pull. Finally, the third stage is controlled by the interaction between the slab and the 660 km transition zone. In the southern region, this results in an important re‐shaping of the slab and intermittent pulses of back‐arc extension. In the northern region, the decrease in the trench retreat can be explained by the entrance of light continental material at the trench.