Imaging the Plumbing System of the Asymmetric Vavilov Spreading Ridge (Tyrrhenian Sea Back-Arc Basin) From Combined Bathymetry and Magnetic Data

Back-arc basins (BABs) are associated with plate margins where crustal shortening, seafloor spreading, and volcanism coexist. The Vavilov basin (Tyrrhenian Sea) is a Pliocene BAB associated with the Apennine-Tyrrhenian Sea subduction system and characterized by mantle exhumation. The NNE-SSW elongated Vavilov seamount represents the easternmost and younger spreading ridge of the Vavilov basin. Here we present results of a morphological and magnetic study of the Vavilov seamount. Our results show that the seamount represents the last stage of the eastward asymmetric opening of the BAB. Its plumbing system consists of a dike swarm emplaced during the reversed Matuyama epoch and a younger shallow reservoir feeding the central and eastern sectors during the normal Brunhes epoch. This evolution is associated with the progressive loading of the edifice due to lava flow emplacement. The asymmetry of the seamount mirrors the asymmetric opening of the Vavilov back-arc basin. Stretching of the crust, seafloor spreading, and volcanism occur in the overriding plate above roll-backing slabs in subduction settings. The Vavilov basin (Tyrrhenian Sea) is a back-arc associated with the eastward retreating of the Apennine-Tyrrhenian Sea subduction system. The NNE-SSW elongated Vavilov submarine volcano represents the easternmost and younger spreading center of this back-arc basin. Combined morphological and magnetic studies of the Vavilov seamount show that the plumbing system of the seamount consists of an early sheet-like intrusion system and a younger, central reservoir feeding the magmatism of the central and eastern sectors of the spreading ridge. This evolution is associated with the progressive growth of the edifice due to lava flow emplacement. The morphological and magnetic asymmetry of the seamount is due to the eastward, asymmetric opening of the Vavilov back-arc basin. Magnetic inverse model images the multi-level plumbing system of the spreading ridge of the Pliocene Vavilov back-arc basinThe spreading ridge evolves from a fissural to a central-type activityThe migration of volcanism in spreading ridges mirrors the asymmetric opening of back-arc basins