Abstract
Three of the most recent rhyolite eruptions in Europe occurred approximately 800 years ago on the island of Lipari, Aeolian Islands, Sicily. These eruptions produced ash and lava deposits that share many of the physical and chemical traits known to exist in hybrid explosive-effusive silicic systems like the Mono Craters and Medicine Lake (USA), in addition to the recently active rhyolite volcanoes Chaitén (2008) and Cordón Caulle (2011), Chile. Here, we present a study on the microtextures, H 2 O concentrations, and δD values of pyroclastic and effusive deposits of three rhyolite eruptions on Lipari (Lami, Forgia Vecchia, and Rocche Rosse). Textural features of obsidian pyroclasts are, within our parameters of analysis, identical among the three centers. The three vents furthermore display overlapping bulk H 2 O concentrations (0.08–1.22 wt.%) that are in turn similar to previous studies on Lipari and other systems. Hydrogen isotope ratios (δD) decrease from −50.9 to −104.9 ‰ as magmatic water drops from 1.22 to 0.08 wt.%. Modeling of these geochemical trends implies that all erupted products degassed along a single coherent trend. This is consistent with a manner of eruption that would have involved simultaneous and repetitive explosive and effusive emission of isotopically heterogeneous gas from a single magma source. Collectively, our observations and analysis point to hybrid effusive-pyroclastic activity and support previous interpretations that Lipari’s three youngest rhyolitic centers were co-eruptive. This, in turn, implies that more than half of the island would have been affected by direct impacts of a single rhyolitic fissure event at ~ 1250 C E.