Cryptic evolved melts beneath monotonous basaltic shield volcanoes in the Galápagos Archipelago

Nature Communications
By: , and 

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Abstract

Many volcanoes erupt compositionally homogeneous magmas over timescales ranging from decades to millennia. This monotonous activity is thought to reflect a high degree of chemical homogeneity in their magmatic systems, leading to predictable eruptive behaviour. We combine petrological analyses of erupted crystals with new thermodynamic models to characterise the diversity of melts in magmatic systems beneath monotonous shield volcanoes in the Galápagos Archipelago (Wolf and Fernandina). In contrast with the uniform basaltic magmas erupted at the surface over long timescales, we find that the sub-volcanic systems contain extreme heterogeneity, with melts extending to rhyolitic compositions. Evolved melts are in low abundance and large volumes of basalt flushing through the crust from depth overprint their chemical signatures. This process will only maintain monotonous activity while the volume of melt entering the crust is high, raising the possibility of transitions to more silicic activity given a decrease in the crustal melt flux.

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Publication type Article
Publication Subtype Journal Article
Title Cryptic evolved melts beneath monotonous basaltic shield volcanoes in the Galápagos Archipelago
Series title Nature Communications
DOI 10.1038/s41467-020-17590-x
Volume 11
Year Published 2020
Language English
Publisher Nature
Contributing office(s) Geology and Geophysics Science Center
Description 3767, 13 p.
Other Geospatial Galápagos Archipelago
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