Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow Planetary Science

Ryuji Okazaki, Takaaki Noguchi, Shin Ichi Tsujimoto, Yu Tobimatsu, Tomoki Nakamura, Mitsuru Ebihara, Shoichi Itoh, Hiroko Nagahara, Shogo Tachibana, Kentaro Terada, Hikaru Yabuta

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We have investigated seven micrometeorites (MMs) from Antarctic snow collected in 2003 and 2010 by means of electron microscopy, X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy (TEM) observation, and noble-gas isotope analysis. Isotopic ratios of He and Ne indicate that the noble gases in these MMs are mostly of solar wind (SW). Based on the release patterns of SW 4He, which should reflect the degree of heating during atmospheric entry, the seven MMs were classified into three types including two least heated, three moderately heated, and two severely heated MMs. The heating degrees are well correlated to their mineralogical features determined by TEM observation. One of the least heated MMs is composed of phyllosilicates, whereas the other consists of anhydrous minerals within which solar flare tracks were observed. The two severely heated MMs show clear evidence of atmospheric heating such as partial melt of the uppermost surface layer in one and abundant patches of dendritic magnetite and Si-rich glass within an olivine grain in the other. It is noteworthy that a moderately heated MM composed of a single crystal of olivine has a 3He/4He ratio of 8.44∈×∈10-4, which is higher than the SW value of 4.64∈×∈10-4, but does not show a cosmogenic 21Ne signature such as 20Ne/21Ne/22Ne∈=∈12.83/0.0284/1. The isotopic compositions of He and Ne in this sample cannot be explained by mixing of a galactic cosmic ray (GCR)-produced component and SW gases. The high 3He/4He ratio without cosmogenic 21Ne signature likely indicates the presence of a 3He-enriched component derived from solar energetic particles.

Original languageEnglish
Article number90
JournalEarth, Planets and Space
Volume67
Issue number1
DOIs
Publication statusPublished - 2015 Dec 22
Externally publishedYes

Fingerprint

micrometeorites
micrometeorite
noble gas
snow
mineralogy
rare gases
isotopes
isotope
solar wind
gases
heating
olivine
transmission electron microscopy
atmospheric heating
signatures
atmospheric entry
phyllosilicate
Raman spectroscopy
energetic particles
solar flares

Keywords

  • Antarctic micrometeorites
  • Atmospheric entry heating
  • Noble gas
  • Solar energetic particles
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

Cite this

Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow Planetary Science. / Okazaki, Ryuji; Noguchi, Takaaki; Tsujimoto, Shin Ichi; Tobimatsu, Yu; Nakamura, Tomoki; Ebihara, Mitsuru; Itoh, Shoichi; Nagahara, Hiroko; Tachibana, Shogo; Terada, Kentaro; Yabuta, Hikaru.

In: Earth, Planets and Space, Vol. 67, No. 1, 90, 22.12.2015.

Research output: Contribution to journalArticle

Okazaki, R, Noguchi, T, Tsujimoto, SI, Tobimatsu, Y, Nakamura, T, Ebihara, M, Itoh, S, Nagahara, H, Tachibana, S, Terada, K & Yabuta, H 2015, 'Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow Planetary Science', Earth, Planets and Space, vol. 67, no. 1, 90. https://doi.org/10.1186/s40623-015-0261-8
Okazaki, Ryuji ; Noguchi, Takaaki ; Tsujimoto, Shin Ichi ; Tobimatsu, Yu ; Nakamura, Tomoki ; Ebihara, Mitsuru ; Itoh, Shoichi ; Nagahara, Hiroko ; Tachibana, Shogo ; Terada, Kentaro ; Yabuta, Hikaru. / Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow Planetary Science. In: Earth, Planets and Space. 2015 ; Vol. 67, No. 1.
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AB - We have investigated seven micrometeorites (MMs) from Antarctic snow collected in 2003 and 2010 by means of electron microscopy, X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy (TEM) observation, and noble-gas isotope analysis. Isotopic ratios of He and Ne indicate that the noble gases in these MMs are mostly of solar wind (SW). Based on the release patterns of SW 4He, which should reflect the degree of heating during atmospheric entry, the seven MMs were classified into three types including two least heated, three moderately heated, and two severely heated MMs. The heating degrees are well correlated to their mineralogical features determined by TEM observation. One of the least heated MMs is composed of phyllosilicates, whereas the other consists of anhydrous minerals within which solar flare tracks were observed. The two severely heated MMs show clear evidence of atmospheric heating such as partial melt of the uppermost surface layer in one and abundant patches of dendritic magnetite and Si-rich glass within an olivine grain in the other. It is noteworthy that a moderately heated MM composed of a single crystal of olivine has a 3He/4He ratio of 8.44∈×∈10-4, which is higher than the SW value of 4.64∈×∈10-4, but does not show a cosmogenic 21Ne signature such as 20Ne/21Ne/22Ne∈=∈12.83/0.0284/1. The isotopic compositions of He and Ne in this sample cannot be explained by mixing of a galactic cosmic ray (GCR)-produced component and SW gases. The high 3He/4He ratio without cosmogenic 21Ne signature likely indicates the presence of a 3He-enriched component derived from solar energetic particles.

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