Explosive eruption of a picrite: The 3930 BP subplinian eruption of Etna volcano (Italy)

We report on a subplinian eruption fed by a picritic magma that occurred 3930 ± 60 BP at Etna volcano. The eruption produced a fallout deposit of 0.183 km 3 (0.055 km 3 DRE), widely dispersed eastward, which represents a marker bed for the Holocene stratigraphy of the volcano. Tephra have a composition of nearly primary magma, owing to their high Mg# (72–79). Glass geothermometry indicates eruptive temperatures (1159–1171°C) ≈ 100° higher than those measured in recent eruptions. High volatile content and unusual enrichment of LIL elements in feeding magma, both suggest addition of fluids in the source zone accounting for a large production of highly buoyant fast‐rising melt. Vigorous degassing of volatile‐rich picritic magma is responsible for the explosive nature of this eruption.