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Meteoriten => Meteorite => Thema gestartet von: karmaka am März 11, 2014, 14:28:36 Nachmittag

Titel: Yamato-82094
Beitrag von: karmaka am März 11, 2014, 14:28:36 Nachmittag
Yamato-82094

Petrology and bulk chemistry of Yamato-82094 (http://www.lpi.usra.edu/meteor/metbull.php?sea=82094&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&code=29288), 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

LINK (http://onlinelibrary.wiley.com/doi/10.1111/maps.12254/abstract)

Yamato-82094 (FOTO) (http://www.nipr.ac.jp/info/notice/image/20140110-21.jpg)

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.

LINK (http://translate.google.de/translate?sl=auto&tl=en&js=n&prev=_t&hl=de&ie=UTF-8&u=http%3A%2F%2Fwww.nipr.ac.jp%2Finfo%2Fnotice%2F20140110-2.html)

Sehr interessant! Vielleicht helfen die neuen Erkenntnisse auch bei der Analyse so manch anderer schwerklassifizierbarer kohliger Chondrite, z.b. NWA 7633 (http://www.lpi.usra.edu/meteor/metbull.php?sea=Nwa+7633&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&code=56616), der vielleicht ja doch kein klassischer CO sein könnte (ohne die beiden hier direkt vergleichen zu wollen).

Oxygen Isotope Plot - Yamato-82094 (http://www.lpi.usra.edu/meteor/makeplot.php?x=-4.52&y=-7.62&plot=16&label=Y-82094%20%28CO3.5%29&method=linear&slope=0.52000)

Oxygen Isotope Plot - NWA 7633 (http://www.lpi.usra.edu/meteor/makeplot.php?x=-5.045;-3.978&y=-8.130;-7.044&plot=16&label=NWA%207633%20%28CO3%29&method=linear&slope=0.52000)


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)

LINK (http://www.hou.usra.edu/meetings/metsoc2013/pdf/5079.pdf)

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

LINK (http://www.lpi.usra.edu/meetings/metsoc2012/pdf/5084.pdf)
Titel: Re: Yamato-82094
Beitrag von: Andyr 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 (http://www.nipr.ac.jp/info/notice/image/20140110-22.jpg)

Gruß

AndyR
Titel: Re: Yamato-82094
Beitrag von: karmaka am Juli 26, 2014, 00:30:40 Vormittag
NOBLE GASES IN YAMATO - 82094, A NEW TYPE OF
CARBONACEOUS CHONDRITE


LINK (http://www.hou.usra.edu/meetings/metsoc2014/pdf/5252.pdf)