A nonmagmatic origin of group-IIE iron meteorites

Wasson, J. T.; Wang, Jianmin

doi:10.1016/0016-7037(86)90348-0

Cited by 105 publications

(111 citation statements)

References 17 publications

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“…They define coherent trends on element-element plots of Ni vs. Ga, Ge, Co, Cu, As, Au, W, and Ir (Wasson and Wang, 1986). Some of these trends can be readily explained by fractional crystallization of a large metallic body and might form during crystallization of a single core.…”

Section: Introductionmentioning

confidence: 92%

“…Eight silicate-bearing iron meteorites have been classified as IIE or IIE-An on the basis of their metal compositions: Weekeroo Station, Colomera, Elga, Netschaëvo, Kodaikanal, Techado, Miles, and Watson (Wasson et al, 1986;Olsen et al, 1994). These meteorites also share a common oxygen isotopic signature, with ⌬ 17 O of 0.59 Ϯ 0.07 for all 8 .…”

Section: Samples and Techniquesmentioning

confidence: 99%

“…The generalized idea that silicate-bearing iron meteorites (e.g., IAB, IIE, and IIICD) and related stony meteorites (e.g., acapulcoites, lodranites, winonaites) formed through partial melting and incomplete differentiation of asteroids which were non-collisionally heated has been widely embraced (see Mittlefehldt et al, 1998 and references therein). In a different model, Wasson and Wang (1986) proposed that IIE iron meteorites formed in individual pools of impactproduced melt in the near-surface region of a chondritic parent body. In the view of Wasson and Wang (1986), melting of the Fe,Ni-FeS and basaltic components and their mixing occurred within these melt pools.…”

Section: Formation Models For Iie Ironsmentioning

confidence: 99%

“…In a different model, Wasson and Wang (1986) proposed that IIE iron meteorites formed in individual pools of impactproduced melt in the near-surface region of a chondritic parent body. In the view of Wasson and Wang (1986), melting of the Fe,Ni-FeS and basaltic components and their mixing occurred within these melt pools. This model was invoked by Olsen et al (1994) to explain the origin of Watson.…”

Section: Formation Models For Iie Ironsmentioning

confidence: 99%

“…Other elementelement trends in IIEs are not easily explained by such a mechanism and are more similar to those in IAB irons. Wasson and Wang (1986) argue that these trends reflect formation of the metallic host by impact melting of the near-surface layer of an asteroid. The IIE irons also display a wide range of silicate inclusion types-from angular, chondrule-bearing inclusions to small globular, strongly differentiated, feldspar-rich inclusions.…”

Section: Introductionmentioning

confidence: 95%

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Chronology and petrology of silicates from IIE iron meteorites: evidence of a complex parent body evolution

Bogard

Garrison

McCoy

2000

Geochimica et Cosmochimica Acta

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Abstract-IIE iron meteorites contain silicate inclusions the characteristics of which suggest a parent body similar to that of H-chondrites. However, these silicates show a wide range of alteration, ranging from Netschaëvo and Techado, the inclusions of which are little altered, to highly differentiated silicates like those in Kodaikanal, Weekeroo Station, and Colomera, which have lost metal and sulfur and are enriched in feldspar. We find these inclusions to show varying degrees of shock alteration. We made 39 Ar-40 Ar age determinations of Watson, Techado, Miles, Colomera, and Sombrerete. Watson has an Ar-Ar age of 3.677 Ϯ 0.007 Gyr, similar to previously reported ages for Kodaikanal and Netschaëvo. We suggest that the various determined radiometric ages of these three meteorites were probably reset by a common impact event. The space exposure ages for these three meteorites are also similar to each other and are considerably younger than exposure ages of other IIEs.39 Ar ages inferred for the other four meteorites analyzed are considerably older than Watson and are: Techado ϭ 4.49 Ϯ 0.01 Gyr, Miles ϭ 4.405 Ϯ 0.012 Gyr, Colomera ϭ 4.470 Ϯ 0.010 Gyr, and Sombrerete ϭ 4.541 Ϯ 0.0012 Gyr. These ages are in fair agreement with previously reported Rb-Sr isochron ages for Colomera and Weekeroo Station. Although several mechanisms to form IIE meteorites have been suggested, it is not obvious that a single mechanism could produce a suite of meteorites with very different degrees of silicate differentiation and with isotopic ages that differ by Ͼ0.8 Gyr. We suggest that those IIEs with older isotopic ages are a product of partial melting and differentiation within the parent body, followed by mixing of silicate and metal while both were relatively hot. Netschaëvo and Watson may have formed by this same process or by impact mixing ϳ4.5 Gyr ago, but their isotopic ages may have been subsequently reset by shock heating. Kodaikanal apparently is required to have formed more recently, in which case impact melting and differentiation seems the only viable process. We see no compelling reasons to believe that IIE silicate and metal derived from different parent bodies or that the parent body of IIEs was the same as that of H-chondrites.

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Section: Introductionmentioning

confidence: 92%

Section: Samples and Techniquesmentioning

confidence: 99%