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

Chamberlain, KJ ORCID: 0000-0002-2010-6182, Barclay, J, Preece, K, Brown, RJ, McIntosh, I and EIMF (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, 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:	37 Earth Sciences, 3703 Geochemistry, 3705 Geology, 3706 Geophysics
Divisions:	Faculty of Science & Engineering Faculty of Science & Engineering > School of Environmental Sciences
Depositing User:	Symplectic Admin
Date Deposited:	17 Jan 2025 09:19
Last Modified:	24 Jan 2026 04:03
DOI:	10.30909/vol.03.01.139153
Related Websites:	Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3189749
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