Constraining the mantle sources of Italian magmatism through high field strength elements and 176Hf/177Hf

High Field Strength Elements (HFSE) are a powerful proxy to investigate specific processes occurring in complex magmatic settings. Being only little released by slab derived fluids/melts, HFSE are not easily overprinted by subduction processes and are also sensitive to peculiar metasomatic processes such as carbonatite infiltrations. We report high-precision HFSE isotope dilution concentration and 176Hf/177Hf data from representative magmas of the Neogene to Quaternary Italian volcanism (i.e., Vesuvius and other Central Italy volcanoes, Tyrrhenian seafloor, Etna, and Pantelleria).

Etna and Vulture volcanic rocks show Nb/Ta ratios much higher than OIB and MORB. The high Nb/Ta cannot be explained by an influence of the Ionian subduction and may reflect carbonatite metasomatism in the mantle. A C-rich metasomatic event explains the large CO2 degassing of Etna and it is consistent with a mantle flow that erodes the bottom portions of the SCLM.

Other Italian volcanoes do not show an anomalously high Nb/Ta with the exception of leucite-bearing rocks from Mid Latin Valley (Central Italy). Hafnium isotopes are partially decoupled from Nd isotopes. Vulture, Vesuvius, and leucite-free magmas from Mid Latin Valley show variations in 143Nd/144Nd, but rather constant 176Hf/177Hf. Given the lower mobility of Hf (with respect to Nd) during subduction processes, the constant 176Hf/177Hf could reflect a common asthenospheric component. Since the Tyrrhenian seafloor and intraplate volcanoes of the region (e.g., Pantelleria and Etna) show more radiogenic Hf, the signature of Vesuvius, Vulture, and leucite-free rocks of the Mid Latin Valley could reflect a less depleted asthenospheric mantle source.