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

Chamberlain, Katy; Barclay, Jenni; Preece, Katie; Brown, Richard; McIntosh, Iona; EIMF

doi:10.30909/vol.03.01.139153

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

Chamberlain, Katy; Barclay, Jenni; Preece, Katie; Brown, Richard; McIntosh, Iona; EIMF

Authors

Katy Chamberlain

Jenni Barclay

Katie Preece

Dr Richard Brown richard.brown3@durham.ac.uk
Associate Professor

Iona McIntosh

EIMF

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.

Citation

Chamberlain, K., Barclay, J., Preece, K., Brown, R., McIntosh, I., & EIMF. (2020). Deep and disturbed: conditions for formation and eruption of a mingled rhyolite at Ascension Island, south Atlantic. Volcanica, 3(1), 139-153. https://doi.org/10.30909/vol.03.01.139153

Journal Article Type	Article
Online Publication Date	May 5, 2020
Publication Date	2020
Deposit Date	May 15, 2020
Publicly Available Date	May 15, 2020
Journal	Volcanica
Publisher	Volcanica
Peer Reviewed	Peer Reviewed
Volume	3
Issue	1
Pages	139-153
DOI	https://doi.org/10.30909/vol.03.01.139153

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