The Kenna ureilite: an ultramafic rock with evidence for igneous, metamorphic, and shock origin

Berkley, J. L.; Brown, Harrison; Keil, K.; Carter, N.L; Mercier, J.; Huss, Glenn I.

doi:10.1016/0016-7037(76)90079-x

Cited by 94 publications

(80 citation statements)

References 36 publications

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“…The finegrained forsterite-metal aggregates are always in contact with magnesian rims of reversely zoned equigranular olivine, and the forsterite of the aggregates may have been produced by reduction, which was proposed by previous workers (Berkley et al, 1976;Goodrich, 1992), at the same time as the formation of the reverse zoning. Magnesian orthopyroxene, with mg ratios of 0.87-0.99 and Wo contents >2 mol%, occurs in fine-grained forsteritemetal aggregates and is similar in chemical composition to orthopyroxene occurring as an interstitial silicate in close association with glass, which suggest that the fine-grained forsteritemetal aggregates may have been produced during the crystallization stage of the interstitial melt.…”

Section: Formation Of Fine-grained Silicatemetal Aggregates and Fine-mentioning

confidence: 85%

“…These are consistent with the results obtained by Goodrich et al (1987a) for other ureilites. The reverse zoning has been explained by reduction reaction for the Fe2Si04 component of equigranular olivine to decompose with the reducing agent graphite (Berkley et al, 1976;Berkley and Jones, 1982;Goodrich, 1992).…”

Section: Formation Of Fine-grained Silicatemetal Aggregates and Fine-mentioning

confidence: 99%

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Petrology of the Asuka 881931 ureilite with special reference to crystallization of interstitial silicate melt

Ikeda

1999

Meteorit & Planetary Scien

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Abstract-The Asuka 881931 meteorite is an unbrecciated ferroan ureilite and consists mainly of equigranular olivine and pigeonite grains, a metal-sulfide network, interstitial silicates, and glass. Peripheral portions of equigranular olivine grains are often replaced by fine-grained forsterite-metal aggregates and sometimes by fine-grained enstatite-metal aggregates. These aggregates may have been produced from the equigranular olivine by reduction. Peripheral portions of equigranular pigeonite grains also are sometimes replaced by fine-grained orthopyroxene aggregates with tiny patches of Si-rich glass and may have been produced from the pigeonite by reduction reaction with silicate melt. Interstitial silicates are mainly orthopyroxene, magnesian pigeonite, high-Ca pyroxene (diopsidelfassaite), and CaO-poor enstatite; and they crystallized from interstitial silicate melt. Interstitial glass is classified into two types-Si-poor and Si-rich. The Si-poor glass is always in contact with equigranular olivine, but the Si-rich glass never contacts equigranular olivine and is in contact with pyroxene and the metal-sulfide network. Both types of glass were produced from an original interstitial silicate melt, but the Si-poor glass formed mainly by fractional crystallization of pyroxenes, and the Si-rich glass may have formed by addition of Si mainly from nearby metal-sulfide melt, as well as crystallization of pyroxenes. The Si-poor and Si-rich melts were finally quenched as interstitial glasses under rapid cooling conditions.

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Section: Formation Of Fine-grained Silicatemetal Aggregates and Fine-mentioning

confidence: 85%

Section: Formation Of Fine-grained Silicatemetal Aggregates and Fine-mentioning

confidence: 99%

Petrology of the Asuka 881931 ureilite with special reference to crystallization of interstitial silicate melt

Ikeda

1999

Meteorit & Planetary Scien

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“…The two main origins that have been considered for ureilites are as partial melting residues (Scott et al, 1993;Warren and Kallemeyn, 1992), or as cumulates (Berkley et al, 1976;Berkley and Jones, 1982;Berkley and Keil, 1980). Although most workers now accept the theory that ureilites are residues rather than cumulates, the augite-bearing ureilites, which represent a small percentage of all ureilites, are likely to be cumulates or paracumulates .…”

Section: Introductionmentioning

confidence: 99%

Osmium isotope systematics of ureilites

Rankenburg

Brandon

Humayun

2007

Geochimica et Cosmochimica Acta

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The 187 Os/ 188 Os for twenty-two ureilite whole rock samples, including monomict, augite-bearing, and polymict lithologies, were examined in order to constrain the provenance and subsequent magmatic processing of the ureilite parent body (or bodies). The Re/Os ratios of most ureilites show evidence for a recent disturbance, probably related to Re mobility during weathering, and no meaningful chronological information can be extracted from the present data set. The ureilite 187 Os/ 188 Os ratios span a range from 0.11739 to 0.13018, with an average of 0.1258 ± 0.0023 (1σ), similar to typical carbonaceous chondrites, and distinct from ordinary or enstatite chondrites. The similar mean of 187 Os/ 188 Os measured for the ureilites and carbonaceous chondrites suggests that the ureilite parent body probably formed within the same region of the solar nebula as carbonaceous chondrites. From the narrow range of the 187 Os/ 188 Os distribution in ureilite meteorites it is further concluded that Re was not significantly fractionated from Os during planetary differentiation and was not lost along with the missing ureilitic melt component. The lack of large Re/Os fractionations requires that Re/Os partitioning was controlled by a metal phase, and thus metal had to be stable throughout the interval of magmatic processing on the ureilite parent body.3

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“…Graphite is the most common polymorph of carbonaceous material in ureilites. Diamonds have been identified in such shocked ureilites as Dyalpur (Mori and Takeda 1988), Goalpara (Vdovykin 1970;Göbel et al 1978), Haverö (Marvin and Wood 1972), and Kenna (Gibson 1976;Berkley et al 1976). One of the least shocked ureilites, Allan Hills 78019 (ALH 78019), contains no diamonds (Berkley and Jones 1982;Wacker 1986;Nakamuta and Aoki 2000;Nakamuta et al 2002), while the less shocked ureilite, Dar al Gani (DaG) 868 (Takeda et al 2001), was found to contain diamonds.…”

Section: Introductionmentioning

confidence: 99%

Noble gases in ureilites released by crushing

Okazaki

Nakamura

Takaoka

et al. 2003

Meteorit & Planetary Scien

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Noble gases in ureilites released by crushingNe for the gases released by crushing are significantly higher than those for heating-released gases. This suggests that host phases of the crush-released gases might be carbonaceous because cosmogenic Ne is produced mainly from elements with a mass number larger than Ne. Based on our optical microscopic observation, tabular-foliated graphite is the major carbon mineral in ALH 78019, while Kenna contains abundant polycrystalline graphite aggregates and diamonds along with minor foliated graphite. There are many inclusions at the edge and within the interior of olivine grains that are reduced by carbonaceous material. Gaps can be seen at the boundary between carbonaceous material and silicates. Considering these petrologic and noble gas features, we infer that possible host phases of crush-released noble gases are graphite, inclusions in reduction rims, and gaps between carbonaceous materials and silicates.The elemental ratios of noble gases released by crushing can be explained by fractionation, assuming that the starting noble gas composition is the same as that of amorphous carbon in ALH 78019. The crush-released noble gases are the minor part of trapped noble gases in ureilites but could be an important clue to the thermal history of the ureilite parent body. Further investigation is needed to identify the host phases of the crush-released noble gases.

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The Kenna ureilite: an ultramafic rock with evidence for igneous, metamorphic, and shock origin

Cited by 94 publications

References 36 publications

Petrology of the Asuka 881931 ureilite with special reference to crystallization of interstitial silicate melt

Petrology of the Asuka 881931 ureilite with special reference to crystallization of interstitial silicate melt

Osmium isotope systematics of ureilites

Noble gases in ureilites released by crushing

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