Publication details for Dr Richard James BrownChamberlain, Katy, Barclay, Jenni, Preece, Katie, Brown, Richard, McIntosh, Iona & EIMF, (2020). Deep and disturbed: conditions for formation and eruption of a mingled rhyolite at Ascension Island, south Atlantic. Volcanica 3(1): 139-153.
- Publication type: Journal Article
- ISSN/ISBN: 2610-3540 (electronic)
- DOI: 10.30909/vol.03.01.139153
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
Author(s) from Durham
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.