TEPHROSTRATIGRAPHY OF MARINE CORE AD91-17 (ADRIATIC SEA) REVISED

Abstract

Revision of the tephrostratigraphy previously proposed for the marine core AD91-17 (Adriatic Sea), supported by energydispersive-spectrometry (EDS) chemical data, has allowed to challenge previous interpretation and proposed a core chronology on the basis of new tephrochronological data. Four different tephra layers were identified and correlated with known eruption from southern Italian volcanoes. The upper tephra layer was tentatively correlated with AD 1631eruption from Somma-Vesuvius, specifically using chemical composition of pyroxenes. The second one (actually represented by two distinct layers), due to pervasive alteration of glass shards, is difficult to be correlated even if is attributed to Somma-Vesuvius volcano. Close to sapropel S1 interruption a rhyolitic layer was correlated to E1/Gabellotto-Fiumebianco eruption from Lipari (Aeolian Islands). The lowermost tephra layers are correlated to the Mercato eruption (Somma-Vesuivus). This seems to confirm the multiple occurrence of Mercato distal deposits in distal areas, as testified by other findings in Mediterranean cores. This suggests that this eruption is probably more complex than previously hypothesised, and characterised by at least two phases fed by the same phonolitic magma.