Cenozoic Volcanic Provinces and Shallow Asthenospheric Volumes in the Circum-Mediterranean: Evidence From Magmatic Geochemistry, Seismic Tomography, and Integrated Geophysical-Petrological Thermochemical Inversion

Abstract

We compile an extensive catalog comprising geochemistry and ages of Cenozoic volcanic provinces in the Mediterranean region, distinguishing between three groups according to the geochemistry of magmatic rocks: intraplate (IVP), subduction-related (SRVP), and mixed-origin volcanic provinces (MVP; intraplate with subduction imprint). In order to relate their spatial distribution to properties of the lithosphere-asthenosphere system, we determine temperature-depth profiles by integrated geophysical-petrological inversion at representative locations, using Rayleigh and Love wave phase velocities, heat flow, rock densities, and accounting for thermochemical conditions. The results confirm the occurrence of thin lithosphere (<100 km) above warm asthenosphere (>1,300°C) in areas of low shear-wave velocities in the shallow upper mantle. Nine shallow asthenospheric volumes (SAVs) between 70 and 300 km depths are identified, forming a partly interconnected belt across the Circum-Mediterranean. A remarkable colocation exists between the SAVs and the intraplate and mixed-origin volcanic provinces (IMVPs). Whereas dense networks of IMVPs have formed above the SAVs, IMVPs are absent in areas of thick mantle lithosphere. Magmatic activity in IMVPs at 60–70 Ma indicates that several SAVs existed already in the Paleogene (Central European, Adriatic, Western Mediterranean, and Moesian SAVs). The formation of SAVs is related either to asthenospheric upwelling caused by slab rollback and back-arc extension (Aegean-Anatolian, Moesian, Pannonian, Western Mediterranean SAVs), or to thermal upwelling (Adriatic, Central European, Middle East [MEA], North African, Rhine-Rhone SAVs), with some of the latter coupled partly with continental rifting (Central European, MEA, North African, Rhine Rhone SAVs).