45 m.y. of Aegean crust and mantle flow driven by trench retreat

Abstract

The available seismic anisotropy data in the Aegean shallow mantle and their relationship with crustal deformation are used for deciphering the lithosphere-scale flow pattern driven by rollback of the Hellenic subduction slab. In the north and central Aegean, the directions of mantle seismic anisotropy trend parallel to stretching lineations in core complexes of the overlying crust, suggesting that crust and mantle have undergone the same direction of flow. At the scale of the entire Aegean, crustal extension is controlled by dextral rotation around a pole located at Scutary-Pec, Albania, that is related to the Hellenic trench retreat. The intensity of mantle anisotropy increases as a function of distance from the pole and of amount of rotation. Surface geology reveals that this rotating flow pattern resulted in strains accumulated since 45 Ma. A slab tear model is suggested to integrate the observed variations of geological events in time and space to subduction dynamics.