Strontium isotopic composition of some recent basic volcanites of the Southern Tyrrhenian Sea and Sicily Channel

The ⁸⁷Sr/⁸⁶Sr ratios have been determined on the volcanic rocks of Ustica, Linosa and Pantelleria Islands. The petrology of these islands is typical of volcanic products belonging to the alkalic suite. The volcanites of Ustica and Linosa Islands are mainly represented by basic terms (alkalibasalts and hawaiites), with minor mugearitic and trachytic differentiates. In addition to alkali-basalts and hawaiites, also some alkaline and peralkaline rocks of Pantelleria have been isotopically analysed. The ⁸⁷Sr/⁸⁶Sr ratios are consistent with a subcrustal origin for all the volcanic products of these islands. Some differences in the ⁸⁷Sr/⁸⁶Sr ratios have been found and tentatively related to an inhomogeneous Rb/Sr distribution in the mantle source material. The genetic relationships of these rocks with some products of the recent Tyrrhenian volcanism are also briefly discussed.