The products of primary magma fragmentation finally revealed by pumice agglomerates

Geology
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Abstract

Following rapid decompression in the conduit of a volcano, magma breaks into ash- to block-sized fragments, powering explosive sub-Plinian and Plinian eruptions that may generate destructive pyroclastic falls and flows. It is thus crucial to assess how magma breaks up into fragments. This task is difficult, however, because of the subterranean nature of the entire process and because the original size of pristine fragments is modified by secondary fragmentation and expansion. New textural observations of sub-Plinian and Plinian pumice lapilli reveal that some primary products of magma fragmentation survive by sintering together within seconds of magma break-up. Their size distributions reflect the energetics of fragmentation, consistent with products of rapid decompression experiments. Pumice aggregates thus offer a unique window into the previously inaccessible primary fragmentation process and could be used to determine the potential energy of fragmentation.

Publication type Article
Publication Subtype Journal Article
Title The products of primary magma fragmentation finally revealed by pumice agglomerates
Series title Geology
DOI 10.1130/G48902.1
Volume 49
Issue 11
Year Published 2021
Language English
Publisher Geological Society of America
Contributing office(s) Volcano Science Center
Description 5 p.
First page 1307
Last page 1311
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