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Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions

Stock, M.J.; Humphreys, M.C.S.; Smith, V.C.; Isaia, R.; Pyle, D.M.

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Authors

M.J. Stock

V.C. Smith

R. Isaia

D.M. Pyle



Abstract

Magma reservoirs are thought to grow relatively slowly, assembling incrementally under volatile-saturated conditions. Eruptions may be triggered by injections of volatile-rich melt, or generation of over-pressure due to protracted crystallization. Here, we analyse fluorine, chlorine and water in apatite crystals trapped at different stages of magma evolution, and in melt inclusions from clinopyroxene and biotite crystals expelled during an explosive eruption of the Campi Flegrei caldera, Italy, about 4,000 years ago. We combine our geochemical analyses with thermodynamic modelling to reconstruct the evolution of magmatic volatile contents leading up to the explosive eruption. We find that the magma reservoir remained persistently water-undersaturated throughout most of its lifetime. Even crystals in contact with the melt shortly before eruption show that the magma was volatile-undersaturated. Our models suggest that the melt reached volatile saturation at low temperatures, just before eruption. We suggest that late-stage volatile saturation probably triggered the eruption, and conclude that ‘priming’ of the magma system for eruption may occur on timescales much shorter than the decadal to centennial timescales thought typical for magma reservoir assembly. Thus, surface deformation pulses that record magma assembly at depth beneath Campi Flegrei and other similar magmatic systems may not be immediately followed by an eruption; and explosive eruptions may begin with little warning.

Citation

Stock, M., Humphreys, M., Smith, V., Isaia, R., & Pyle, D. (2016). Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions. Nature Geoscience, 9(3), 249-254. https://doi.org/10.1038/ngeo2639

Journal Article Type Article
Acceptance Date Dec 23, 2015
Online Publication Date Feb 1, 2016
Publication Date Mar 1, 2016
Deposit Date Jan 5, 2016
Publicly Available Date Mar 29, 2024
Journal Nature Geoscience
Print ISSN 1752-0894
Electronic ISSN 1752-0908
Publisher Nature Research
Peer Reviewed Peer Reviewed
Volume 9
Issue 3
Pages 249-254
DOI https://doi.org/10.1038/ngeo2639

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