Publication Date:
2007
Description:
〈b〉Impact vesiculation – a new trigger for volcanic bubble growth and degassing〈/b〉〈br〉
D. A. Rothery, J. M. Sumner, O. Spieler, and D. B. Dingwell〈br〉
eEarth Discuss., 2, 151-167, doi:10.5194/eed-2-151-2007, 2007〈br〉
〈b〉Revised manuscript has not been submitted〈/b〉 (discussion: closed, 3 comments)〈br〉
We highlight a potentially important trigger for bubble
growth and degassing in volcanic bombs. We have successfully triggered
bubble growth in previously unvesiculated samples of silicate melt during
experiments to simulate volcanic bomb impact, by firing pellets at, and
dropping weights onto, melt samples. We call this phenomenon "impact
vesiculation". Further work is required on real volcanic bombs to establish
the extent to which impact vesiculation occurs in nature. However, our
experiments are sufficient to demonstrate that impact vesiculation is a
viable processes and should be borne in mind in analysis of bubble
populations and degassing histories of bombs and spatter-fed lava flows.
Degassing caused by impact vesiculation can occur only at ground-level, so
any attempt to calculate the amount of erupted gas available for transport
high into the atmosphere by convection above the source of a fountain-fed
lava flow that is based on subtracting the volatile content of fluid
inclusions from the volatile content of the resulting lava flow would be an
overestimate if significant impact vesiculation has occurred.
Print ISSN:
1815-3836
Electronic ISSN:
1815-3844
Topics:
Geosciences
