Chemical Alteration of Volcanic Ash Due to Simulated Lightning
Abstract
Lightning-induced volcanic spherules (LIVS) have been found within ashfall deposits of several recent explosive volcanic eruptions (e.g., Redoubt, USA 2009; Ejyafjallajökull, Iceland 2010; Pavlof, USA 2016; Sakurajima, Japan 2015). Recent experiments have shown that temperatures generated by lightning are high enough to melt ash (>2000 ℃), which then solidifies as glass spheres or tear-shaped particles. While previous studies have mainly focused on formation and morphology of LIVS, few have examined their chemical properties. This research aims to understand how lightning alters the chemistry of volcanic material by analyzing lightning-induced particles generated by high-current impulse experiments conducted at peak currents of 7 kA and 25 kA using ash samples produced from andesitic pumice clasts. The lightning-induced textures are primarily spherical but also include tear-drops, tubes, and hairs. In addition, the particles show a variety of colors including white, black, and red, which would suggest that oxidation and/or reduction reactions have occurred within the starting material. Chemical analyses of these particles were conducted using energy dispersive spectrometry and wavelength dispersive spectrometry with a scanning electron microscope and electron probe micro-analyzer, respectively. These chemical analyses will be presented, as they pose important implications for understanding the effects of lightning on pyroclast and atmospheric composition.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V12B..08W
- Keywords:
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- 8428 Explosive volcanism;
- VOLCANOLOGY;
- 8434 Magma migration and fragmentation;
- VOLCANOLOGY;
- 8445 Experimental volcanism;
- VOLCANOLOGY;
- 8486 Field relationships;
- VOLCANOLOGY