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ToolsFrey, H. M., Manon, M. R., Barclay, J., Davies, B. V., Walters, S. A., Cole, P. D., Christopher, T. E. and Joseph, E. P. (2024) Petrology of the explosive deposits from the April 2021 eruption of La Soufrière volcano, St Vincent:A time-series analysis of microlites. In: The 2020-2021 Eruption of La Soufriere Volcano, St Vincent. Geological Society Special Publications, 539 . Geological Society of London, pp. 201-230.
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Abstract
After more than three months of lava dome extrusion, La Soufrière (St Vincent) transitioned to a series of explosive eruptions in April 2021. Here we present a time-series petrologic analysis of the phenocryst and microlite populations during the first c. 48 h of explosivity to constrain ascent conditions and processes that drove changes in behaviour. Primary eruptive products were crystal-rich (45–50 vol%) basaltic andesites with similar phenocryst phase assemblages and compositions. The change in eruptive style is consistent with over-pressurization as a consequence of second boiling from anhydrous microlite crystallization. The microlites display variation between the explosive phases, with two populations: (1) ‘inherited’ − normally zoned high-An plagioclase (>An 70) + olivine (Fo 62–79) + clinopyroxene + titanomagnetite, inferred to have crystallized at depths >15 km and high water pressures; (2) ‘juvenile’ − unzoned plagioclase (An 45–65) + clinopyroxene + orthopyroxene + intermediate pyroxene (Wo 12–38) + titanomagnetite, inferred to have crystallized upon ascent due to decompression and degassing. Scoria from the first explosions featured extensive groundmass crystallization and a significant ‘inherited’ microlite population. Later explosions had a more abundant ‘juvenile’ microlite population and lower crystallinity, consistent with more rapid ascent from depth, initiated by decompression following initial blasts and destruction of the lava dome.
| Item Type: | Book Section |
|---|---|
| Additional Information: | Funding Information: This study was supported by the United States National Science Foundation (NSF) through Grants for Rapid Response Research (Award # 2132566) to H.F. and M.M. J.B., B.V.D. and P.C. were supported by the UK Natural Environment Research Council (NERC) through an Urgency Grant (NE/W000725/1). |
| Faculty \ School: | Faculty of Science > School of Environmental Sciences |
| UEA Research Groups: | Faculty of Science > Research Groups > Geosciences |
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| Depositing User: | LivePure Connector |
| Date Deposited: | 10 May 2023 15:30 |
| Last Modified: | 28 Jan 2025 11:17 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/92018 |
| DOI: |
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