Deep and disturbed: conditions for formation and eruption of a mingled rhyolite at Ascension Island, south Atlantic

Chamberlain, Katy Jane, Barclay, Jenni, Preece, Katie, Brown, Richard and McIntosh, Iona (2020) Deep and disturbed: conditions for formation and eruption of a mingled rhyolite at Ascension Island, south Atlantic. Volcanica, 3 (1). pp. 139-153. ISSN 2610-3540

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Abstract

The generation of felsic melts (through open or closed system processes) within ocean island volcanoes has been a key area of study since their identification. At Ascension Island in the south Atlantic, explosively erupted felsic melts have, to date, demonstrated a marked absence of signs of magma mixing and crustal assimilation. Here we present the first observations of a fall deposit from Ascension Island recording both macro- and micro-scale evidence for magma mingling. Geochemical analyses of mineral and glass phases, coupled with volatile concentrations of melt inclusions highlight the role of lower-crustal partial melting to produce rhyolitic magmas. Glass textures and the lack of zoning in major mineral phases indicate that mingling with a mafic melt occurred shortly prior to eruption. These inferences of a deep rhyolite production zone, coupled with rapid ascent rates highlight the challenges in forecasting a similar style of eruption at Ascension Island in the future.

Item Type: Article
Uncontrolled Keywords: ascension island,crustal melting,magma genesis,magma mingling,earth and planetary sciences (miscellaneous),geochemistry and petrology,geology,geophysics ,/dk/atira/pure/subjectarea/asjc/1900/1901
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: LivePure Connector
Date Deposited: 12 May 2020 23:59
Last Modified: 09 Jul 2021 06:46
URI: https://ueaeprints.uea.ac.uk/id/eprint/75127
DOI: 10.30909/vol.03.01.139153

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