Composition and origin of Nuevo Laredo Trend eucrites

Warren, P. H.; Jerde, Eric A.

doi:10.1016/0016-7037(87)90082-2

Cited by 118 publications

(82 citation statements)

References 32 publications

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“…7, in which a compatible element or parameter (e.g., Mg#) is plotted against an incompatible element (e.g., Sm). Similar diagrams were used by Warren and Jerde (1987) to argue that most noncumulate eucrites originated predominantly as residual liquids. In Fig.…”

Section: Mg# Versus Samariummentioning

confidence: 81%

“…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

210

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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Section: Mg# Versus Samariummentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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

210

241

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“…In this model, total melting would not be expected. Over the last 30 years a number of additional models have been proposed that are basically variants of these (e.g., Warren and Jerde, 1987;Hewins and Newsom, 1988;Righter and Drake, 1997;Ruzicka et al, 1997;Warren, 1997;Mittlefehldt and Lindstrom, 2003;Greenwood et al, 2005), however, consensus on a single model of HED petrogenesis has been elusive.…”

Section: Introductionmentioning

confidence: 99%

Zinc isotopes in HEDs: Clues to the formation of 4-Vesta, and the unique composition of Pecora Escarpment 82502

Paniello¹,

Moynier²,

Beck

et al. 2012

Geochimica et Cosmochimica Acta

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The d 66 Zn (permil deviation of the 66 Zn/ 64 Zn ratio from a terrestrial standard) values for a suite of 20 non-Antarctic HED (howardite-eucrite-diogenite) meteorites and one mesosiderite, and for eight Antarctic eucrites and diogenites, were measured in order to determine the role of volatization in the formation of their presumed parent body, the asteroid 4-Vesta. The 20 non-Antarctic HEDs had d 66 Zn values that ranged from À2.0& to +1.67&, with a mean value of À0.01 ± 0.39& (2 se); this range likely represents a small-scale heterogeneity due to brecciation induced by multiple impacts. The non-Antarctic eucrites (d 66 Zn = +0.00 ± 0.58& (2 se), n = 12) were isotopically the same as the diogenites (d 66 Zn = À0.31 ± 0.80& (2 se), n = 4), and the howardites (d 66 Zn = +0.26 ± 0.37& (2 se), n = 4). On average, non-Antarctic eucrite falls were isotopically heavier (+0.50&) than non-Antarctic finds (À1.00&). The Antarctic finds studied were all unbrecciated samples, and they were significantly heavier than the non-Antarctic samples with a d 66 Zn range of +1.63& to +6.22& for four eucrites (mean, +4.32&) and +0.94& to +1.60& for three diogenites (mean + 1.23&), excluding one anomalous sample, while their Zn concentration is significantly lower than the brecciated samples. These data suggest that the unbrecciated eucrites probably represent the eucritic crust shortly after differentiation and cooling of the parent asteroid, at which time volatization of lighter zinc isotopes led to an isotopically heavy crust. Early impact events caused the ejection of these unbrecciated meteorites, which were subsequently spared from brecciation caused by multiple additional impacts on the much larger Vesta. The range of d 66 Zn values and Zn concentration for the brecciated HEDs in this study supports a major contribution to the Vestan surface by chondritic impactors (À1.30 < d 66 Zn < +0.76& for ordinary and carbonaceous chondrites). The anomalous eucrite PCA 82502 (d 66 Zn = À7.75&) is significantly isotopically lighter than the other HEDs and is the natural sample with the lightest Zn isotopic composition reported in the solar system to date. This meteorite most likely originated from a distinct parent body.

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“…In contrast, others have suggested that magmatic activity on the HED parent body was dominated by a large-scale melting event, which generated a global magma ocean (e.g., Ikeda and Takeda 1985;Righter and Drake 1997;Ruzicka et al 1997;Takeda 1997;Warren 1997;Greenwood et al 2005). According to this view, the chemistry of eucritic melts can be explained in terms of fractional crystallization processes (e.g., Stolper 1977;Warren and Jerde 1987). Contamination of the eucritic magmas by liquids derived by partial melting of the asteroid's crust has also been proposed (Barrat et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of diogenites: Still more diversity in their parental melts

Barrat

Yamaguchi

Greenwood

et al. 2008

Meteorit & Planetary Scien

100

154

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Abstract-We report on the major and trace element abundances of 18 diogenites, and O-isotopes for 3 of them. Our analyses extend significantly the diogenite compositional range, both in respect of Mg-rich (e.g., Meteorite Hills [MET] 00425, MgO = 31.5 wt%) and Mg-poor varieties (e.g., Dhofar 700, MgO = 23 wt%). The wide ranges of siderophile and chalcophile element abundances are well explained by the presence of inhomogeneously distributed sulfide or metal grains within the analyzed chips. The behavior of incompatible elements in diogenites is more complex, as exemplified by the diversity of their REE patterns. Apart from a few diogenite samples that contain minute amounts of phosphate, and whose incompatible element abundances are unlike the orthopyroxene ones, the range of incompatible element abundances, and particularly the range of Dy/Yb ratios in diogenites is best explained by the diversity of their parental melts. We estimate that the FeO/MgO ratios of the diogenite parental melts range from about 1.4 to 3.5 and therefore largely overlap the values obtained for non-cumulate eucrites. Our results rule out the often accepted view that all the diogenites formed from parental melts more primitive than eucrites during the crystallization of a magma ocean. Instead, they point to a more complex history, and suggest that diogenites were derived from liquids produced by the remelting of cumulates formed from the magma ocean.

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Composition and origin of Nuevo Laredo Trend eucrites

Cited by 118 publications

References 32 publications

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

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

Zinc isotopes in HEDs: Clues to the formation of 4-Vesta, and the unique composition of Pecora Escarpment 82502

Geochemistry of diogenites: Still more diversity in their parental melts

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