Alteration of volcanic ash glass chemistry due to lightning

Woods, T.; Genareau, Kimberly; Klüss, Joni

doi:10.1016/j.jvolgeores.2021.107340

Cited by 4 publications

(9 citation statements)

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“…LIVS are solid or hollow glass spheres with diameters ranging between 1 and 100 μm (Genareau et al, 2015(Genareau et al, , 2019Woods et al, 2021). Reproduced during laboratory experiments using high-current impulses, LIVS can form through a combination of mechanisms, including melting and re-solidification of individual grains <150 μm (Wadsworth et al, 2017), fusion of multiple molten grains into single or aggregated particles (Genareau et al, 2017), and detachment of expanding bubbles from vesiculating grains (Genareau et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

A Raman Spectroscopic Study of Lightning‐Induced Glass Produced From Five Mineral Phases

Woods,

Genareau,

Park

2024

Earth and Space Science

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Lightning‐induced volcanic spherules (LIVS) are glasses produced by the rapid melting and solidification of molten volcanic ash grains. High temperatures generated by lightning will alter the physical and chemical properties of minerals exposed to the discharge. Laboratory experiments reveal that LIVS glass composition varies depending on the starting material, exhibiting heterogeneous compositional features common in other glasses created by cloud‐to‐ground lightning, nuclear explosions, and high velocity impact events. This study uses scanning electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy to investigate the structure and Raman signatures of lightning‐induced glass spherules manufactured from five igneous minerals (<32 μm powders of albite, labradorite, augite, hornblende, and magnetite). LIVS were created through high‐current impulse experiments using peak currents of 25 and 40 kA. Analysis of the post‐experimental albite, labradorite, augite, and hornblende LIVS reveal primarily homogeneous silicate or aluminosilicate glasses with limited heterogeneity. Their amorphous Raman spectra are comparable to rhyolitic and mafic natural glasses along with Na2O‐K2O‐Al2O3‐SiO2, CaCO3‐Al2O3‐SiO2, and CaO‐MgO‐SiO2 synthetic glass networks. A few of the augite and hornblende LIVS spectra exhibit premelting effects, which occur below the melting point and represent the onset of cation disordering in phases that remain crystalline. Magnetite samples produced crystal‐rich, glass‐poor LIVS characterized by the growth of dendritic microcrystals and crystalline spectra that also contain a few bands alluding to the composition of their silicate–phosphate glass matrix. By understanding these chemical changes induced by lightning, we can extract information from other types of glasses produced during high temperature, short duration events.

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Section: Introductionmentioning

confidence: 99%

A Raman Spectroscopic Study of Lightning‐Induced Glass Produced From Five Mineral Phases

Woods,

Genareau,

Park

2024

Earth and Space Science

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“…In contrast, Woods et al. (2021) used high‐current impulse experiments (25 and 40 kA) on andesite volcanic ash and observed chemically complex glasses with compositional banding and elemental heterogeneity over small (μm) distances, representing the mixing of glass and various mineral components (plagioclase, magnetite, etc.) while in a molten state.…”

Section: Introductionmentioning

confidence: 99%

“…The glass composition of lightning‐altered volcanic ash depends on the initial glass chemistry and mineral content as well as the degree of mixing between completely or partially melted components, which is constrained by the peak current and proximity to the channel axis (Genareau et al., 2017; Mueller et al., 2018; Woods et al., 2021). For instance, Mueller et al.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, Mueller et al (2018) injected chemically homogeneous phonolite glass grains into an artificially generated electric arc (welding arc at a current of 25A), which yielded homogeneous glasses with vesicle-rich textures depleted in some elements (e.g., F, Cl, Na). In contrast, Woods et al (2021) used high-current impulse experiments (25 and 40 kA) on andesite volcanic ash and observed chemically complex glasses with compositional banding and elemental heterogeneity over small (μm) distances, representing the mixing of glass and various mineral components (plagioclase, magnetite, etc.) while in a molten state.…”

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confidence: 99%

“…The glass composition of lightning-altered volcanic ash depends on the initial glass chemistry and mineral content as well as the degree of mixing between completely or partially melted components, which is constrained by the peak current and proximity to the channel axis (Genareau et al, 2017;Mueller et al, 2018;Woods et al, 2021). For instance, Mueller et al (2018) injected chemically homogeneous phonolite glass grains into an artificially generated electric arc (welding arc at a current of 25A), which yielded homogeneous glasses with vesicle-rich textures depleted in some elements (e.g., F, Cl, Na).…”

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Magnetic Properties of Lightning‐Induced Glass Produced From Five Mineral Phases

Woods,

Feinberg,

Genareau

et al. 2023

JGR Solid Earth

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The physical properties of minerals are modified by the high temperatures of volcanic lightning during explosive eruptions. Alteration involves rapid heating and volatilization, melting, and fusion of ash grains within the discharge channel, followed by rapid quenching into new glassy textures. High current impulse experiments reveal that lightning alters not only the morphology and mineralogy of volcanic ash but also its magnetic properties. We investigate lightning‐induced magnetic changes in five igneous minerals (< 32 µm powders of albite, labradorite, augite, hornblende, and magnetite) by comparing hysteresis parameters before and after impulse experiments conducted at peak currents of 25 and 40 kA. Both the paramagnetic and ferrimagnetic behaviors of the samples were altered, which we interpret as a superposition of two processes. (1) Rapid melting allows iron contained within inclusions of Fe‐oxides and Fe‐bearing silicates to diffuse into the newly formed melt, thereby increasing the paramagnetism of the resulting glass. (2) Nucleation and growth of magnetite from the newly formed melt increases the ferrimagnetic behavior of the post‐experimental samples. Nominally non‐Fe‐bearing silicates like albite and labradorite have significantly increased paramagnetism and ferrimagnetism. Fe‐bearing silicates like augite and hornblende contain higher concentrations of ferrimagnetic inclusions, from which Fe diffuses into the newly formed melt, thereby increasing paramagnetism while decreasing ferrimagnetism. Experiments conducted on magnetite produced new magnetite crystals with dendritic habits. Although specific to volcanic ash, these results provide important insights into the magnetism of other materials affected by lightning on Earth, the Moon, and throughout the solar system.

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Volcanic electrification: recent advances and future perspectives

et al. 2022

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The electrification of volcanic plumes has been described intermittently since at least the time of Pliny the Younger and the 79 AD eruption of Vesuvius. Although sometimes disregarded in the past as secondary effects, recent work suggests that the electrical properties of volcanic plumes reveal intrinsic and otherwise inaccessible parameters of explosive eruptions. An increasing number of volcanic lightning studies across the last decade have shown that electrification is ubiquitous in volcanic plumes. Technological advances in engineering and numerical modelling, paired with close observation of recent eruptions and dedicated laboratory studies (shock-tube and current impulse experiments), show that charge generation and electrical activity are related to the physical, chemical, and dynamic processes underpinning the eruption itself. Refining our understanding of volcanic plume electrification will continue advancing the fundamental understanding of eruptive processes to improve volcano monitoring. Realizing this goal, however, requires an interdisciplinary approach at the intersection of volcanology, atmospheric science, atmospheric electricity, and engineering. Our paper summarizes the rapid and steady progress achieved in recent volcanic lightning research and provides a vision for future developments in this growing field.

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Alteration of volcanic ash glass chemistry due to lightning

Cited by 4 publications

References 50 publications

A Raman Spectroscopic Study of Lightning‐Induced Glass Produced From Five Mineral Phases

A Raman Spectroscopic Study of Lightning‐Induced Glass Produced From Five Mineral Phases

Magnetic Properties of Lightning‐Induced Glass Produced From Five Mineral Phases

Volcanic electrification: recent advances and future perspectives

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