Autor Thema: Yamato-82094  (Gelesen 1097 mal)

Offline karmaka

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Yamato-82094
« am: März 11, 2014, 14:28:36 Nachmittag »
Yamato-82094

Petrology and bulk chemistry of Yamato-82094, a new type of carbonaceous chondrite

    M. Kimura, J. A. Barrat, M. K. Weisberg, N. Imae, A. Yamaguchi, H. Kojima

Meteoritics & Planetary Science, 4 MAR 2014, DOI: 10.1111/maps.12254

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Yamato-82094 (FOTO)

Zitat
Abstract

Carbonaceous chondrites are classified into several groups. However, some are ungrouped. We studied one such ungrouped chondrite, Y-82094, previously classified as a CO. In this chondrite, chondrules occupy 78 vol%, and the matrix is distinctly poor in abundance (11 vol%), compared with CO and other C chondrites. The average chondrule size is 0.33 mm, different from that in C chondrites. Although these features are similar to those in ordinary chondrites, Y-82094 contains 3 vol% Ca-Al-rich inclusions and 5% amoeboid olivine aggregates (AOAs). Also, the bulk composition resembles that of CO chondrites, except for the volatile elements, which are highly depleted. The oxygen isotopic composition of Y-82094 is within the range of CO and CV chondrites. Therefore, Y-82094 is an ungrouped C chondrite, not similar to any other C chondrite previously reported. Thin FeO-rich rims on AOA olivine and the mode of occurrence of Ni-rich metal in the chondrules indicate that Y-82094 is petrologic type 3.2. The extremely low abundance of type II chondrules and high abundance of Fe-Ni metal in the chondrules suggest reducing condition during chondrule formation. The depletion of volatile elements indicates that the components formed under high-temperature conditions, and accreted to the parent body of Y-82094. Our study suggests a wider range of formation conditions than currently recorded by the major C chondrite groups. Additionally, Y-82094 may represent a new, previously unsampled, asteroidal body.

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Sehr interessant! Vielleicht helfen die neuen Erkenntnisse auch bei der Analyse so manch anderer schwerklassifizierbarer kohliger Chondrite, z.b. NWA 7633, der vielleicht ja doch kein klassischer CO sein könnte (ohne die beiden hier direkt vergleichen zu wollen).

Oxygen Isotope Plot - Yamato-82094

Oxygen Isotope Plot - NWA 7633


PS:

Ganz so neu scheinen die Erkenntnisse allerdings nicht zu sein. Bereits in den letzten zwei Jahren gab es entsprechende Untersuchungen zu Y-82094:

Abundant Anomolous Chondrules in an Ungrouped Carbonaceous Chondrite, Y-82094 (9/2013)

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Ungrouped Carbonaceous Chondrite, Yamato 82094: Characteristic Features and Classification (9/2012)

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« Letzte Änderung: März 11, 2014, 14:54:55 Nachmittag von karmaka »

Offline Andyr

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Re: Yamato-82094
« Antwort #1 am: März 11, 2014, 20:44:56 Nachmittag »
78 vol% Chondren sind in der Tat sehr ungewöhnlich für einen kohligen Chondrite. Hier ein interessantes DS-Foto von Yamato 82094:

http://www.nipr.ac.jp/info/notice/image/20140110-22.jpg

Gruß

AndyR

Offline karmaka

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Re: Yamato-82094
« Antwort #2 am: Juli 26, 2014, 00:30:40 Vormittag »
NOBLE GASES IN YAMATO - 82094, A NEW TYPE OF
CARBONACEOUS CHONDRITE


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