Minimum-size detection limit for volcanic glass particles using automated scanning electron microscopy

Ice cores contain a detailed record of fallout from large volcanic eruptions. Identification of volcanic glass particles is used to aid in dating ice cores (tephrachronology). In addition, it should be possible to relate concentrations of volcanogenically-derived species; silicate glass particles, sulfate (from oxidation of SO2), chloride and fluoride to atmospheric levels which existed shortly after eruption. This information, coupled with proxy meteorological records from the core, can be used to assess the climatic impact from major volcanic eruptions.Automated scanning electron microscopy has been used to detect volcanic glass particles >1 μm in diameter in ice core meltwater samples filtered onto Nuclepore filters. It is important to be able to detect submicrometer volcanic glass particles because of their longer atmospheric residence time and the fact that they comprise a significant portion of the number of glass particles deposited in an ice core. Existing procedures for automated analysis of micrometer size particles need to be modified to efficiently analyze submicrometer particles.

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Discovery of argon in air-hydrate crystals in a deep ice core using scanning electron microscopy and energy-dispersive X-ray spectroscopy

Journal of Glaciology ◽

10.1017/jog.2021.115 ◽

2021 ◽

pp. 1-10

Author(s):

Tsutomu Uchida ◽

Wataru Shigeyama ◽

Ikumi Oyabu ◽

Kumiko Goto-Azuma ◽

Fumio Nakazawa ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Raman Spectroscopy ◽

Ice Core ◽

Ice Cores ◽

Inert Gases ◽

Energy Dispersive ◽

Air Bubbles ◽

X Ray ◽

Scanning Electron

Abstract Tiny samples of ancient atmosphere in air bubbles within ice cores contain argon (Ar), which can be used to reconstruct past temperature changes. At a sufficient depth, the air bubbles are compressed by the overburden pressure under low temperature and transform into air-hydrate crystals. While the oxygen (O2) and nitrogen (N2) molecules have indeed been identified in the air-hydrate crystals with Raman spectroscopy, direct observational knowledge of the distribution of Ar at depth within ice sheet and its enclathration has been lacking. In this study, we applied scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to five air-hydrate crystals in the Greenland NEEM ice core, finding them to contain Ar and N. Given that Ar cannot be detected by Raman spectroscopy, the method commonly used for O2 and N2, the SEM-EDS measurement method may become increasingly useful for measuring inert gases in deep ice cores.

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A comparative study of the morphology, chemical composition and weathering of rhyolitic and andesitic glass

Clay Minerals ◽

10.1180/claymin.1980.015.2.07 ◽

1980 ◽

Vol 15 (2) ◽

pp. 165-173 ◽

Cited By ~ 24

Author(s):

J. H. Kirkman ◽

W. J. McHardy

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

New Zealand ◽

Chemical Composition ◽

Electron Probe ◽

Volcanic Glass ◽

Chemical Activity ◽

Rapid Rate ◽

Bonding Characteristics ◽

Scanning Electron

AbstractThe morphology of volcanic glass particles in rhyolitic and andesitic tephra of central North Island and Taranaki areas of New Zealand has been studied by scanning electron microscopy. Electron probe analyses of the glasses are compared with those of the clays to which they weather. Loss of silica characterizes the weathering of both glasses. The rapid rate of weathering of andesitic glass is attributed to its occurrence as fine, soft microlites and extensive substitution of Al for Si in the structure. Rhyolitic glass weathers more slowly because it occurs as hard and brittle particles containing relatively little alumina. It is suggested that the structure, chemical composition and chemical activity of allophane is governed largely by the chemical composition and bonding characteristics of the parent glass.

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