Volcanic products emitted at Vulcano (Aeolian Islands, Italy) over the last 1000 years have been investigated through an integrated textural and micro-analytical study on plagioclase crystals, which allowed us to draw a detailed model of the internal structure of the magmatic system. Two centers have been active during hystorical times in Vulcano: Vulcanello, where poorly evolved magmas were mainly erupted and La Fossa Cone, which erupted more differentiated products. We found that magma storage and mixing occur into an articulated plumbing system developed from the mantle-crust boundary to the surface. A basaltic-shoshonitic reservoir, probably located at the depth of the Moho, fed the activity of both centers. Starting from Moho depth, our data indicate the presence of three main magma levels beneath La Fossa Cone, which were variously reactivated over the whole period of activity. Plagioclase crystals registered the ascent and continuous episodes of magma recharge plus mixing that affected the shallower reservoirs. The first stages of activity at Vulcanello were fed by poorly differentiated melts that directly rose from the deep basaltic-shoshonitic reservoir, residing for a short period of time into the crust before the eruption. Indeed, Sr diffusion modeling in plagioclase indicates limited residence times (<2 years) for crystals erupted at Vulcanello if compared to those of the La Fossa Cone eruptions (2-10 years). Our time estimations suggest that magma feeding the activity at La Fossa have been stored for most of the time in reservoirs located below the plagioclase nucleation depth (~11 km of depth), intruding at shallower levels only few years before the eruption onset. According to our model, magmatic eruptions at Vulcano could be related to the ascent of deep basic magma that triggers a sort of “reaction chain” through subsequent episodes of recharge and mixing toward the upper magmatic reservoirs.
|Titolo:||Pre-eruptive magmatic processes and their timescales at Vulcano island (southern Italy) during the last 1000 years|
NICOTRA, EUGENIO (Corresponding)
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|