The control of magma crystallinity on the fluctuations in gas composition at open vent basaltic volcanoes

Woitischek, Julia and Edmonds, Marie and Woods, Andrew W. (2020) The control of magma crystallinity on the fluctuations in gas composition at open vent basaltic volcanoes. Scientific Reports, 10 (1). ISSN 2045-2322 DOI https://doi.org/10.1038/s41598-020-71667-7

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Official URL: https://doi.org/10.1038/s41598-020-71667-7

Abstract

Basaltic open vent volcanoes are major global sources of volcanic gases. Many of these volcanoes outgas via intermittent Strombolian-type explosions separated by periods of passive degassing. The gas emitted during the explosions has high molar CO2/SO2 and SO2/HCl ratios, while during the passive degassing these ratios are lower. We present new laboratory experiments in a model volcanic conduit, which suggest that these differences in gas geochemistry are a consequence of gas migration through crystal-rich magma. We show that gas may flow along channels through the particle-laden liquid and, at a critical depth, the gas may displace an overlying crystal-rich plug en masse, producing a growing slug of gas. Owing to the friction on the walls of the conduit, this plug becomes progressively sheared and weakened until gas enriched in the least soluble volatiles breaks through, causing an explosion at the surface. When the gas slug bursts, liquid is drawn up in its wake, which exsolves the more soluble volatile components, which then vent passively at the surface until the next explosive slug-bursting event.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
07 - Gold Open Access
12 - PhD
Journal or Publication Title: Scientific Reports
Volume: 10
Identification Number: https://doi.org/10.1038/s41598-020-71667-7
Depositing User: Sarah Humbert
Date Deposited: 06 Nov 2020 01:35
Last Modified: 06 Nov 2020 01:35
URI: http://eprints.esc.cam.ac.uk/id/eprint/4919

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