Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites
Additional mineralogical and chemical studies of the Yamato meteorites are under way. The mode analysis and the optical properties in thin sections are examined under a microscope. Chondrites occur in all of the Yamato meteorites with the exception of Yamato (b). Yamato (a) is composed mainly of pyr...
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National Institute of Polar Research
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ftdoajarticles:oai:doaj.org/article:0129f20fcada46ba8aa32658d62a75a8 2023-05-15T13:51:55+02:00 Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites Makoto SHIMA Akihiko OKADA Masako SHIMA 1974-01-01T00:00:00Z https://doi.org/10.15094/00007733 https://doaj.org/article/0129f20fcada46ba8aa32658d62a75a8 EN JA eng jpn National Institute of Polar Research https://doi.org/10.15094/00007733 https://doaj.org/toc/0085-7289 https://doaj.org/toc/2432-079X doi:10.15094/00007733 0085-7289 2432-079X https://doaj.org/article/0129f20fcada46ba8aa32658d62a75a8 Antarctic Record, Iss 48, Pp 91-99 (1974) Geography (General) G1-922 article 1974 ftdoajarticles https://doi.org/10.15094/00007733 2022-12-30T22:54:11Z Additional mineralogical and chemical studies of the Yamato meteorites are under way. The mode analysis and the optical properties in thin sections are examined under a microscope. Chondrites occur in all of the Yamato meteorites with the exception of Yamato (b). Yamato (a) is composed mainly of pyroxene, olivine and opaque minerals (iron phase, sulphide phase, etc.). Pyroxene occurs as enstatite (En_<98>) and olivine as forsterite (Fo_<95>). Yamato (b) is composed mainly of pyroxene of En_<74>Fs_<26> composition. Yamato (c) is composed of olivine and opaque minerals containing carbon compounds; olivine has the composition of Fo_<60> Fa_<40>. Yamato (d) is composed of olivine, pyroxene and opaque minerals; olivine has the composition of Fo_<90>Fa_<10> and pyroxene the composition of En_<85>Fs_<15>. Some chondrules in these meteorites are distinguished by their particular mineral composition. The chemical compositions of the Yamato meteorites were determined by the wet chemical analysis. From 0.5 g aliquots of powdered samples, several fractions were taken out by the fractional dissolution method. Yamato (a) contains much metallic iron, water-soluble calcium sulphide (oldhamite) and only acid insoluble silicates. Yamato (b) contains essentially no metallic iron or nickel, but is high in Si and Mg. Yamato (c) has an extremely small concentration of metallic iron whereas total iron is very high. This iron consists mainly of magnetite. Yamato (d) is a high iron chondrite group. The trace elements, W, Re, Os, Ir, Pt, Au, Hg, Tl, Bi, Th and U, were determined utilizing a spark source mass spectrograph MS7 with electrical ion detection. The abundance distribution patterns of the trace elements confirm the result of the already classified reference meteorites. The solidification ages of the Yamato meteorites were determined by the K-Ar method. Yamato (a), (b), (c) and (d) are estimated to be 2.3, 4.4, 12.2 and 15.4×10^7 yr. respectevely. By these results, the ... Article in Journal/Newspaper Antarc* Antarctica Directory of Open Access Journals: DOAJ Articles Yamato ENVELOPE(35.583,35.583,-71.417,-71.417) |
institution |
Open Polar |
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op_collection_id |
ftdoajarticles |
language |
English Japanese |
topic |
Geography (General) G1-922 |
spellingShingle |
Geography (General) G1-922 Makoto SHIMA Akihiko OKADA Masako SHIMA Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites |
topic_facet |
Geography (General) G1-922 |
description |
Additional mineralogical and chemical studies of the Yamato meteorites are under way. The mode analysis and the optical properties in thin sections are examined under a microscope. Chondrites occur in all of the Yamato meteorites with the exception of Yamato (b). Yamato (a) is composed mainly of pyroxene, olivine and opaque minerals (iron phase, sulphide phase, etc.). Pyroxene occurs as enstatite (En_<98>) and olivine as forsterite (Fo_<95>). Yamato (b) is composed mainly of pyroxene of En_<74>Fs_<26> composition. Yamato (c) is composed of olivine and opaque minerals containing carbon compounds; olivine has the composition of Fo_<60> Fa_<40>. Yamato (d) is composed of olivine, pyroxene and opaque minerals; olivine has the composition of Fo_<90>Fa_<10> and pyroxene the composition of En_<85>Fs_<15>. Some chondrules in these meteorites are distinguished by their particular mineral composition. The chemical compositions of the Yamato meteorites were determined by the wet chemical analysis. From 0.5 g aliquots of powdered samples, several fractions were taken out by the fractional dissolution method. Yamato (a) contains much metallic iron, water-soluble calcium sulphide (oldhamite) and only acid insoluble silicates. Yamato (b) contains essentially no metallic iron or nickel, but is high in Si and Mg. Yamato (c) has an extremely small concentration of metallic iron whereas total iron is very high. This iron consists mainly of magnetite. Yamato (d) is a high iron chondrite group. The trace elements, W, Re, Os, Ir, Pt, Au, Hg, Tl, Bi, Th and U, were determined utilizing a spark source mass spectrograph MS7 with electrical ion detection. The abundance distribution patterns of the trace elements confirm the result of the already classified reference meteorites. The solidification ages of the Yamato meteorites were determined by the K-Ar method. Yamato (a), (b), (c) and (d) are estimated to be 2.3, 4.4, 12.2 and 15.4×10^7 yr. respectevely. By these results, the ... |
format |
Article in Journal/Newspaper |
author |
Makoto SHIMA Akihiko OKADA Masako SHIMA |
author_facet |
Makoto SHIMA Akihiko OKADA Masako SHIMA |
author_sort |
Makoto SHIMA |
title |
Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites |
title_short |
Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites |
title_full |
Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites |
title_fullStr |
Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites |
title_full_unstemmed |
Study of the Extraterrestrial Materials at Antarctica, IV. : On the Yamato Meteorites |
title_sort |
study of the extraterrestrial materials at antarctica, iv. : on the yamato meteorites |
publisher |
National Institute of Polar Research |
publishDate |
1974 |
url |
https://doi.org/10.15094/00007733 https://doaj.org/article/0129f20fcada46ba8aa32658d62a75a8 |
long_lat |
ENVELOPE(35.583,35.583,-71.417,-71.417) |
geographic |
Yamato |
geographic_facet |
Yamato |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Antarctic Record, Iss 48, Pp 91-99 (1974) |
op_relation |
https://doi.org/10.15094/00007733 https://doaj.org/toc/0085-7289 https://doaj.org/toc/2432-079X doi:10.15094/00007733 0085-7289 2432-079X https://doaj.org/article/0129f20fcada46ba8aa32658d62a75a8 |
op_doi |
https://doi.org/10.15094/00007733 |
_version_ |
1766255956203667456 |