Chemical composition of the Kobe meteorite; Neutron-induced prompt gamma ray analysis study.

Oura, Y.; Ebihara, Mitsuru; Yoneda, Shigekazu; Nakamura, Noboru

doi:10.2343/geochemj.36.295

Cited by 18 publications

(20 citation statements)

References 20 publications

(35 reference statements)

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“…The results indicate that Kobe can be classified as a CK4 carbonaceous chondrite; it is the first carbonaceous chondrite known to fall in Japan. The bulk chemical compositions, including trace elements, and oxygen isotopic compositions of Kobe are consistent with the CK classification Oura et al, 2002). CK is a recently established type of carbonaceous chondrites.…”

Section: Introductionsupporting

confidence: 48%

The Kobe CK carbonaceous chondrite: petrography, mineralogy and metamorphism

Tomeoka

Kojima

Ishii

et al. 2005

Journal of Mineralogical and Petrological Sciences

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A petrographic and mineralogical study of Kobe indicates that it can be classified as a CK4 carbonaceous chondrite. CK chondrites differ from other groups of carbonaceous chondrites, because all normal CK chondrites have been thermally metamorphosed. Olivine and plagioclase are the two most abundant minerals in Kobe. Olivine is very homogeneous in composition, which is consistent with the metamorphic feature of Kobe. However, plagioclase shows large grain to grain compositional variations. The matrix and chondrule mesostases exhibit pronounced silicate darkening. They contain unusual olivine that contains numerous small vesicles (< 0.1 3 μm in diameter) and inclusions (< 0.1 10 μm) of magnetite, pentlandite and minor plagioclase, pyroxene and chlorapatite. The vesicular olivine is particularly abundant in regions that exhibit a high degree of darkening. The vesicular olivine is clearly the principal cause of the silicate darkening. Plagioclase in matrix and chondrule mesostases also contains numerous small vesicles and inclusions of magnetite, pyroxene and minor pentlandite and olivine. The texture and mineralogy of the vesicular olivine and plagioclase suggest that they recrystallized from melts that were produced from olivine and plagioclase in the matrix by shock. We suggest that the shock event occurred at a relatively mild pressure and a high temperature, probably at the state where the meteorite underwent thermal metamorphism.

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Section: Introductionsupporting

confidence: 48%

The Kobe CK carbonaceous chondrite: petrography, mineralogy and metamorphism

Tomeoka

Kojima

Ishii

et al. 2005

Journal of Mineralogical and Petrological Sciences

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“…LEW 86258 plots off the trend. Bulk compositional data from Quijano-Rico and W‰nke (1969), Kallemeyn et al (1991), Dreibus et al (1995), Oura et al (2002Oura et al ( , 2004, and Huber et al (2004, Forthcoming).…”

Section: Source Of Brown Stainingmentioning

confidence: 99%

A weathering index for CK and R chondrites

Rubin

Huber

2005

Meteoritics &Amp; Planetary Science

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Abstract-We present a new weathering index (wi) for the metallic-Fe-Ni-poor chondrite groups (CK and R) based mainly on transmitted light observations of the modal abundance of crystalline material that is stained brown in thin sections: wi-0, <5 vol%; wi-1, 5-25 vol%; wi-2, 25-50 vol%; wi-3, 50-75 vol%; wi-4, 75-95 vol%; wi-5, >95 vol%; wi-6, significant replacement of mafic silicates by phyllosilicates. Brown staining reflects mobilization of oxidized iron derived mainly from terrestrial weathering of Ni-bearing sulfide. With increasing degrees of terrestrial weathering of CK and R chondrites, the sulfide modal abundance decreases, and S, Se, and Ni become increasingly depleted. In addition, bulk Cl increases in Antarctic CK chondrites, probably due to contamination from airborne sea mist.

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“…This sample was labeled "Kobe C3mix". The sample was divided into three parts; C-3mix-1 (0.65 g) for rare gas analyses (Matsumoto et al, 2001), C-3mix-2 (0.093 g) for acceleration mass spectrometry (AMS) analysis of cosmogenic nuclides (Coffee et al, 2000), and C-3mix-3 (0.19 g) for isotope dilution mass spectrometry (IDMS) and prompt gamma-ray analyses (PGA) (Oura et al, 2002). Y-693 falls into weathering category A, and its petrography has been reported by Noguchi (1993) and Nakamura et al (1993).…”

Section: Samplesmentioning

confidence: 99%