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Highly explosive basaltic eruptions driven by CO₂ exsolution.

ABSTRACT: The most explosive basaltic scoria cone eruption yet documented (>20 km high plumes) occurred at Sunset Crater (Arizona) ca. 1085 AD by undetermined eruptive mechanisms. We present melt inclusion analysis, including bubble contents by Raman spectroscopy, yielding high total CO₂ (approaching 6000 ppm) and S (~2000 ppm) with moderate H₂O (~1.25 wt%). Two groups of melt inclusions are evident, classified by bubble vol%. Modeling of post-entrapment modification indicates that the group with larger bubbles formed as a result of heterogeneous entrapment of melt and exsolved CO₂ and provides evidence for an exsolved CO₂ phase at magma storage depths of ~15 km. We argue that this exsolved CO₂ phase played a critical role in driving this explosive eruption, possibly analogous to H₂O exsolution driving silicic caldera-forming eruptions. Because of their distinct gas compositions relative to silicic magmas (high S and CO₂), even modest volume explosive basaltic eruptions could impact the atmosphere.

SUBMITTER: Allison CM

PROVIDER: S-EPMC7801484 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Highly explosive basaltic eruptions driven by CO2 exsolution.

Allison Chelsea M CM Roggensack Kurt K Clarke Amanda B AB

Nature communications 20210111 1

The most explosive basaltic scoria cone eruption yet documented (>20 km high plumes) occurred at Sunset Crater (Arizona) ca. 1085 AD by undetermined eruptive mechanisms. We present melt inclusion analysis, including bubble contents by Raman spectroscopy, yielding high total CO2 (approaching 6000 ppm) and S (~2000 ppm) with moderate H2O (~1.25 wt%). Two groups of melt inclusions are evident, classified by bubble vol%. Modeling of post-entrapment modification indicates that t ...[more]

PMID: 33431860

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