Experimental partial melting of the Allende (CV) and Murchison (CM) chondrites and the origin of asteroidal basalts

Jurewicz, A. J. G.; Mittlefehldt, David W.; Jones, J. H.

doi:10.1016/0016-7037(93)90098-h

Cited by 126 publications

(166 citation statements)

References 18 publications

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“…2), suggesting that they might come from the same body. Ibitira and the angrites are both more depleted in Na and K than the basaltic eucrites and eucrite-like and angrite-like partial melts can be produced from a single source by changing the oxygen fugacity (Jurewicz et al, 1993). However, we lack breccias containing both types of basalt and it is more plausible that they come from separate bodies.…”

Section: Ibitiramentioning

confidence: 95%

Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites

Scott

Greenwood

Franchi

et al. 2009

Geochimica et Cosmochimica Acta

147

177

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A few eucrites have anomalous oxygen isotopic compositions. To help understand their origin and identify additional samples, we have analyzed the oxygen isotopic compositions of 18 eucrites and four diogenites. Except for five eucrites, these meteorites have ∆ 17 O values that lie within 2σ of their mean value viz., -0.242±0.016‰, consistent with igneous isotopic homogenization of Vesta. The five exceptional eucrites-NWA 1240, Pasamonte (both clast and matrix samples), PCA 91007, A-881394, and Ibitira-have ∆ 17 O values that lie respectively 4σ, 5σ, 5σ, 15σ, and 21σ away from this mean value. NWA 1240 has a δ 18 O value that is 5σ below the mean eucrite value. Four of the five outliers are unbrecciated and unshocked basaltic eucrites, like NWA 011, the first eucrite found to have an anomalous oxygen isotopic composition. The fifth outlier, Pasamonte, is composed almost entirely of unequilibrated basaltic clasts. Published chemical data for the six eucrites with anomalous oxygen isotopic compositions (including NWA 011) exclude contamination by chondritic projectiles as a source of the oxygen anomalies. Only NWA 011 has an anomalous Fe/Mn ratio, but several anomalous eucrites have exceptional Na, Ti, or Cr concentrations. We infer that the six anomalous eucrites are probably derived from five distinct Vesta-like parent bodies (Pasamonte and PCA 91007 could come from one body). These anomalous eucrites, like many unbrecciated eucrites from Vesta, are probably deficient in brecciation and shock effects because they were sequestered in small asteroids (~10 km diameter) during the Late Heavy Bombardment following ejection from Vesta-like bodies. The preservation of Vesta's crust and the lack of deeply buried samples from the hypothesized Vestalike bodies are consistent with the removal of these bodies from the asteroid belt by gravitational perturbations from planets and protoplanets, rather than by collisonal grinding.

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Section: Ibitiramentioning

confidence: 95%

Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites

Scott

Greenwood

Franchi

et al. 2009

Geochimica et Cosmochimica Acta

147

177

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“…Redox proxies indicate that angrites probably formed in a relatively oxidized environment (IW+1 to +2; Jurewicz et al, 1991Jurewicz et al, , 1993McKay et al, 1994), even though the exact redox conditions are difficult to quantify. Dauphas et al (2009a) Kitts and Lodders (1998).…”

Section: Redox-controlled Iron Isotope Fractionation On the Angrite Pmentioning

confidence: 99%

Iron isotope fractionation in planetary crusts

Wang

Moynier

Dauphas

et al. 2012

Geochimica et Cosmochimica Acta

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We present new high precision iron isotope data (d 56 Fe vs. IRMM-014 in per mil) for four groups of achondrites: one lunar meteorite, 11 martian meteorites, 32 howardite-eucrite-diogenite meteorites (HEDs), and eight angrites. Angrite meteorites are the only planetary materials, other than Earth/Moon system, significantly enriched in the heavy isotopes of Fe compared to chondrites (by an average of +0.12& in d 56 Fe). While the reason for such fractionation is not completely understood, it might be related to isotopic fractionation by volatilization during accretion or more likely magmatic differentiation in the angrite parent-body. We also report precise data on martian and HED meteorites, yielding an average d 56 Fe of 0.00 ± 0.01&. Stannern-trend eucrites are isotopically heavier by +0.05& in d 56 Fe than other eucrites. We show that this difference can be ascribed to the enrichment of heavy iron isotopes in ilmenite during igneous differentiation. Preferential dissolution of isotopically heavy ilmenite during remelting of eucritic crust could have generated the heavy iron isotope composition of Stannern-trend eucrites. This supports the view that Stannern-trend eucrites are derived from main-group eucrite source magma by assimilation of previously formed asteroidal crust.These new results show that iron isotopes are not only fractionated in terrestrial and lunar basalts, but also in two other differentiated planetary crusts. We suggest that igneous processes might be responsible for the iron isotope variations documented in planetary crusts.

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“…Jones and coworkers (Jones et al, 1996;Jurewicz et al, 1993Jurewicz et al, , 1995 suggested that the moderately incompatible-compatible elements Cr, Sc, and V may be key to understanding the petrogenesis of eucrites. According to these authors, the Cr abundances of eucrites especially favor a partial melt origin, rather than a residual melt origin, for noncumulate eucrites (Jurewicz et al, 1993;Jones et al, 1996).…”

Section: Chromium Versus Scandiummentioning

confidence: 99%

“…According to these authors, the Cr abundances of eucrites especially favor a partial melt origin, rather than a residual melt origin, for noncumulate eucrites (Jurewicz et al, 1993;Jones et al, 1996).…”

Section: Chromium Versus Scandiummentioning

confidence: 99%

“…They may have originally formed in one of two ways, either as ( I ) partial (primary) melts of the HED parent body that experienced comparatively little modification by fractional crystallization processes (Stolper, 1977;Consolmagno and Drake, 1977;Jones, 1984, Jurewicz et al, 1993, or (2) melts produced from the same or similar magmas that had earlier crystallized diogenites (Mason, 1967;Warren, 1985;Ikeda and Takeda, 1985;Warren and Jerde, 1987;Hewins and Newsom, 1988;Grove and Bartels, 1992). The large and apparently continuous variations in mineral compositions and mineral assemblages in howardites and polymict eucrites (e.g., Duke and Silver, 1967;Delaney et al, 1984;Takeda and Mori, 1985;Ikeda and Takeda, 1985) provide compelling evidence for the importance of fractionating magmas in the HED parent body.…”

Section: Introductionmentioning

confidence: 99%

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Vesta as the howardite, eucrite and diogenite parent body: Implications for the size of a core and for large‐scale differentiation

Ruzicka

Snyder

Taylor

1997

Meteorit & Planetary Scien

207

241

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Abstract-If Vesta is the parent body of the howardite, eucrite, and diogenite (HED) meteorites, then geochemical and petrologic constraints for the meteorites may be used in conjunction with astronomical constraints for the size and mass of Vesta to (1) determine the size of a possible metal core in Vesta and (2) model the igneous differentiation and internal structure of Vesta.The density of Vesta and petrologic models for HED meteorites together suggest that the amount of metal in the parent body is <25 mass%, with a best estimate of -5%, assuming no porosity. For a porosity of up to 5% in the silicate fraction of the asteroid, the permissible metal content is <30%. These results suggest that any metal core in the HED parent body and Vesta is not unusually large.A variety of geochemical and other data for HED meteorites are consistent with the idea that they originated in a magma ocean. It appears that diogenites formed by crystal accumulation in a magma ocean cumulate pile and that most noncumulate eucrites (excepting such eucrites as Bouvante and Stannem) formed by subsequent crystallization of the residual melts. Modelling results suggest that the HED parent body is enriched in rare earth elements by a factor of -2.5-3.5 relative to CI-chondrites and that it has approximately chondritic Mg/Si and AVSc ratios. Stokes settling calculations for a Vesta-wide, nonturbulent magma ocean suggest that early-crystallizing magnesian olivine, orthopyroxene, and pigeonite would have settled relatively quickly, permitting fractional crystallization to occur, but that later-crystallizing phases would have settled (or floated) an order of magnitude more slowly, allowing, instead, a closer approach to equilibrium crystallization for the more evolved (eucritic) melts. This would have inhibited the formation of a plagioclase-flotation crust on Vesta.Plausible models for the interior of Vesta, which are consistent with the data for HED meteorites and Vesta, include a metal core ( 4 3 0 km radius), an olivine-rich mantle (-65-220 km thick), a lower crustal unit (-1243 km thick) composed of pyroxenite, from which diogenites were derived, and an upper crustal unit (-23-42 km thick), from which eucrites originated. The present shape of Vesta (with -60 km difference in the maximum and minimum radius) suggests that all of the crustal materials, and possibly some of the underlying olivine from the mantle, could have been locally excavated or exposed by impact cratering.

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Experimental partial melting of the Allende (CV) and Murchison (CM) chondrites and the origin of asteroidal basalts

Cited by 126 publications

References 18 publications

Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites

Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites

Iron isotope fractionation in planetary crusts

Vesta as the howardite, eucrite and diogenite parent body: Implications for the size of a core and for large‐scale differentiation

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