Open-vent volcanoes fuelled by depth-integrated magma degassing
Publication Date
2022Journal Title
Bulletin of Volcanology
ISSN
0258-8900
Publisher
Springer Science and Business Media LLC
Volume
84
Issue
3
Language
en
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Edmonds, M., Liu, E., & Cashman, K. (2022). Open-vent volcanoes fuelled by depth-integrated magma degassing. Bulletin of Volcanology, 84 (3) https://doi.org/10.1007/s00445-021-01522-8
Abstract
<jats:title>Abstract</jats:title><jats:p>Open-vent, persistently degassing volcanoes—such as Stromboli and Etna (Italy), Villarrica (Chile), Bagana and Manam (Papua New Guinea), Fuego and Pacaya (Guatemala) volcanoes—produce high gas fluxes and infrequent violent strombolian or ‘paroxysmal’ eruptions that erupt very little magma. Here we draw on examples of open-vent volcanic systems to highlight the principal characteristics of their degassing regimes and develop a generic model to explain open-vent degassing in both high and low viscosity magmas and across a range of tectonic settings. Importantly, gas fluxes from open-vent volcanoes are far higher than can be supplied by erupting magma and independent migration of exsolved volatiles is integral to the dynamics of such systems. The composition of volcanic gases emitted from open-vent volcanoes is consistent with its derivation from magma stored over a range of crustal depths that in general requires contributions from both magma decompression (magma ascent and/or convection) and iso- and polybaric second boiling processes. Prolonged crystallisation of water-rich basalts in crustal reservoirs produces a segregated exsolved hydrous volatile phase that may flux through overlying shallow magma reservoirs, modulating heat flux and generating overpressure in the shallow conduit. Small fraction water-rich melts generated in the lower and mid-crust may play an important role in advecting volatiles to subvolcanic reservoirs. Excessive gas fluxes at the surface are linked to extensive intrusive magmatic activity and endogenous crustal growth, aided in many cases by extensional tectonics in the crust, which may control the longevity and activity of open-vent volcanoes. There is emerging abundant geophysical evidence for the existence of a segregated exsolved magmatic volatile phase in magma storage regions in the crust. Here we provide a conceptual picture of gas-dominated volcanoes driven by magmatic intrusion and degassing throughout the crust.</jats:p>
Keywords
Review Article, Open-vent volcanoes, Depth-integrated magma degassing, Gas-dominated volcanoes
Sponsorship
NERC (via University of Leeds) (RGEVEA100399)
NERC (via British Geological Survey (BGS)) (GA/16F/078/RMS E6138S)
Identifiers
s00445-021-01522-8, 1522
External DOI: https://doi.org/10.1007/s00445-021-01522-8
This record's URL: https://www.repository.cam.ac.uk/handle/1810/334812
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
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