New geochemical constraints on the nature of the carbonatite signature in Ionian slab-edge magmatism (Southern Italy)

Abstract

The Cenozoic basaltic volcanism in the Hyblean Plateau, southern Sicily, plays a role in the investigation of the complex Southern Tyrrhenian tectono-magmatic scenario. The geochemical features of new Hyblean rock samples presented in this study identify a hitherto overlooked variability in the carbonatitic metasomatism experienced by the continental lithospheric mantle that sourced the Hyblean magmas. Indeed, a subset of the samples exhibits a distinctive trace element signature with respect to the known Hyblean magmatism that requires significant input from a carbon-rich agent. This finding further supports the tectono-magmatic model in which fragments of the Hyblean carbonatitic metasomatized lithospheric roots were recycled in the slab-tear magmatism of the nearby Etna volcano, contributing to its anomalous high CO2 emission. Notably, the spatial variability in the carbonatitic metasomatism documented by the newly analysed Hyblean volcanic rocks suggests the idea that such variability could be a consequence of ancient metasomatic events driven by deep-mantle CO2 remobilization at the contact between the continental and oceanic lithospheric domains presently located in the Southern Tyrrhenian area. A similar scenario may have contributed to the origin of the carbonatitic signature exhibited by slab-tear volcanic sites elsewhere in this geodynamically complex area.