Caldera-forming eruptions of mushy magma modulated by feedbacks between ascent rate, gas retention/loss and bubble/crystal framework interaction.

ABSTRACT: Caldera-forming eruptions of mushy silicic magma are among the most catastrophic natural events on Earth. In such magmas, crystals form an interlocking framework when their content reaches critical thresholds, resulting in the dramatic increase in viscous resistance to flow. Here, we propose a new mechanism for the ascent of mushy magma based on microstructural observations of crystal-rich silicic pumices and lavas from the Central Andes and decompression experiments. Microstructural data include spherical vesicles and jigsaw-puzzle association of broken crystals in pumices, whereas there is limited breakage of crystals in lavas. These observations insinuate that shearing of magma during ascent was limited. Decompression experiments reveal contrasting interaction between growing gas bubble

SUBMITTER: Okumura S 

PROVIDER: S-EPMC6825124 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature