High CO2 content in magmas of the explosive andesitic Enco eruption of Mocho-Choshuenco volcano (Chile)

Jean-Guillaume Feignon, Nicolas Cluzel, Federica Schiavi, Séverine Moune, Olivier Roche, Jorge Clavero, Pierre Schiano, Marion Auxerre

Onderzoeksoutput: Articlepeer review

2 Citaten (Scopus)

Samenvatting

Mocho-Choshuenco volcano has produced several highly explosive eruptions during its history, which make it one of the most hazardous volcanoes in the southern volcanic zone of Chile, although it is still relatively little studied to date. We present a geochemical study of the products of the sub-Plinian, andesitic, Enco eruption that occurred about 1600 years ago. We determined the major and trace elements compositions, as well as the volatile (H2O, CO2, Cl, and S) contents of melt inclusions trapped in minerals (olivine, plagioclase, and pyroxene) using electron microprobe, ion microprobe (SIMS), and 3D confocal Raman mapping. Though the whole-rock composition of the Enco magma is andesitic (60.2 ± 1.1 wt.% SiO2), the melt inclusions have SiO2 contents ranging from 50.3 to 67.3 wt.%, following the magmatic series of Mocho-Choshuenco, and the compositions of the most mafic melt inclusions are close to those of the most mafic erupted magmas. Geochemical modeling indicates that mixing occurred between a mafic magma and an andesitic-to-dacitic magma. Glass analysis revealed typical parental arc magma values for H2O (2.6–3.8 wt.%), S (116–1936 ppm), and Cl (620–1439 ppm). However, CO2 contents are very high in some melt inclusions with concentrations above 4000 ppm (measured in the glass), suggesting trapping depths >  ~ 17–22 km. Presence of solid carbonates inside inclusion-hosted bubbles clearly indicates that the CO2 contents measured in the glass phase were minimum values. We conclude that a CO2-rich basaltic magma ascended and mixed with a shallower andesitic magma. The magma cooled and exsolved high amounts of CO2, which may have dramatically increased the pressure and triggered the highly explosive Enco eruption.
Originele taal-2English
Artikelnummer40
Aantal pagina's20
TijdschriftBulletin of Volcanology
Volume84
Nummer van het tijdschrift4
DOI's
StatusPublished - apr 2022
Extern gepubliceerdJa

Bibliografische nota

Funding Information:
Open access funding provided by University of Vienna. This research was financed by the French National Research Institute for sustainable Development (IRD), the French Government Laboratory of Excellence initiative No. ANR-10-LABX-0006, the Region Auvergne and the European Regional Development Fund, and the Chilean Science Commission (Fondecyt projects 1070162 and 1090387). This is Laboratory of Excellence ClerVolc contribution number 533.

Funding Information:
The authors thank the Associate Editor, Tobias Fischer, as well as Tom Shea, and an anonymous reviewers for their constructive and helpful reviews. We thank Jean-Luc Devidal (LMV) for assistance with the electron microprobe and LA-ICP-MS and Etienne Deloule for his help with the ion probe at CRPG Nancy.

Publisher Copyright:
© 2022, The Author(s).

Copyright:
Copyright 2022 Elsevier B.V., All rights reserved.

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