Insights into eruption style using remote sensing and petrology at Mt Etna, Sicily
Abstract
The magmatic gas phase is a critical component in the triggering and driving of basaltic explosive eruptions. At Etna it is thought that a substantial gas phase exists prior to eruption, and this pre-eruptive gas may play a role in triggering lava fountaining. Any measurements of volatiles and degassing must therefore attempt to capture both the gases exsolved at magma reservoir pressures and emitted prior to or during eruption, as well as those volatiles that exsolve during eruption. To this end, we combine remotely-sensed observations of sulfur dioxide emissions and estimates of lava flux with a geochemical characterization of melt inclusions for some recent fountaining eruptions of Etna. Time series of gas and lava fluxes show that the gas-melt ratio of the erupted products varies throughout an eruption, with high gas-melt ratios at the onset of fountaining which then decline with time, which has implications for fountain triggering and understanding transitions between eruption styles. The analysis indicates that a large fraction of sulfur partitions into the vapour phase prior to eruption, supporting the conclusions of previous work. We use our results, and data from the literature, to construct an empirical model relating the proportion of 'excess' sulfur to the size of the eruption and we use this to estimate the SO2 emission that accompanied the 1669 eruption of Etna, showing it may had a highly significant regional environmental impact. We examine the major, trace and volatile geochemistry of olivine-hosted melt inclusions in tephra for additional insights into magma fractionation, mixing and degasing prior to eruption.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.V41B2792S
- Keywords:
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- 1036 GEOCHEMISTRY Magma chamber processes