Genesis of the Angra dos Reis and other achondritic meteorites

Ma, M.-S.; Murali, A. V.; Schmitt, R. A.

doi:10.1016/0012-821x(77)90135-2

Cited by 48 publications

(18 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1), or for the presence of the 0.75 µm Fe 2+ -Fe 3+ charge transfer absorption feature. The latter is strong evidence for an Fe 3+ -free (or nearly so) clinopyroxene on BoûnÏmcová, consistent with the composition of angritic clinopyroxene (Hazen and Finger 1977;Ma et al 1977). The former suggests that BoûnÏmcová differs from Angra dos Reis in terms of abundances and/or site occupancies of transition series elements.…”

Section: Mineralogymentioning

confidence: 49%

Asteroid 3628 Božněmcová: Covered with angrite-like basalts?

Cloutis

Binzel

Burbine

et al. 2006

Meteoritics &Amp; Planetary Science

View full text Add to dashboard Cite

Abstract-A detailed analysis of the reflectance spectrum of asteroid 3628 BoûnÏmcová, previously identified as a possible ordinary chondrite parent body, indicates that its surface consists of an assemblage dominated by clinopyroxene and plagioclase feldspar. The clinopyroxene is Fe 2+ -bearing (likely in the range Fs~1 0-20 ), with >90% of the Fe 2+ being present in the M1 crystallographic site (spectral type A). The clinopyroxene:plagioclase feldspar ratio is between ~2 and 3 (~55-75% clinopyroxene, ~20-33% plagioclase feldspar). If olivine is present, the clinopyroxene:olivine ratio is >~3 (<20% olivine). The derived mineralogy of BoûnÏmcová is most similar, but not identical, to the known angrite meteorites. The data suggest that BoûnÏmcová formed by melting and differentiation of an oxidized chondritic precursor and probably represents an unsampled angrite-like body.

show abstract

Section: Mineralogymentioning

confidence: 49%

Asteroid 3628 Božněmcová: Covered with angrite-like basalts?

Cloutis

Binzel

Burbine

et al. 2006

Meteoritics &Amp; Planetary Science

View full text Add to dashboard Cite

show abstract

“…The Li/Yb ratio in the Moon is the same as that in the BSE (O'Neill 1991a). Remarkably, even Angra dos Reis, so very depleted in the other alkalis, contains 2 ppm Li (Tera et al 1970), implying that Li/YbZ0.5 ( Yb from Ma et al 1977). Correlation of Li/Yb with Na/Ti or K/U is poor (figure 2b), indicating that it is little affected by post-nebular volatilization.…”

Section: Mechanisms Of Volatile Element Depletion (A ) Incomplete Conmentioning

confidence: 99%

“…The mean crustal Martian K/Th determined by the Mars Odyssey Gamma Ray Spectrometer is 5330G220 (Taylor et al 2006), implying that K/UZ20!10 3 , also higher than the magmatic ratio derived here, but not sufficiently so as to invalidate the arguments presented below. NWA 011 PB 0.93 ( Yamaguchi et al 2002) 11 (Yamaguchi et al 2002) 75 (Yamaguchi et al 2002) w60 ( Yamaguchi et al 2002) 3 Angrite PB 0.028G0.010 (Mittlefehldt et al 2002) 0.3G0.1 (Tera et al 1970;Ma et al 1977) 95G13 (Mittlefehldt et al 2002) 71G4 (Longhi 1999 The derived planetary Mn/Na ratios are compared with the Mn/Na ratio in chondrites in figure 1. In every STB for which we have the necessary 'basaltic' samples, the calculated planetary Mn/Na is greatly elevated above the chondritic range.…”

Section: Post-nebular Volatilizationmentioning

confidence: 99%

Collisional erosion and the non-chondritic composition of the terrestrial planets

O’Neill

Palme

2008

Phil. Trans. R. Soc. A.

251

188

View full text Add to dashboard Cite

The compositional variations among the chondrites inform us about cosmochemical fractionation processes during condensation and aggregation of solid matter from the solar nebula. These fractionations include: (i) variable Mg-Si-RLE ratios (RLE: refractory lithophile element), (ii) depletions in elements more volatile than Mg, (iii) a cosmochemical metal-silicate fractionation, and (iv) variations in oxidation state. Moon-to Mars-sized planetary bodies, formed by rapid accretion of chondrite-like planetesimals in local feeding zones within 10 6 years, may exhibit some of these chemical variations. However, the next stage of planetary accretion is the growth of the terrestrial planets from approximately 10 2 embryos sourced across wide heliocentric distances, involving energetic collisions, in which material may be lost from a growing planet as well as gained. While this may result in averaging out of the 'chondritic' fractionations, it introduces two non-chondritic chemical fractionation processes: post-nebular volatilization and preferential collisional erosion. In the latter, geochemically enriched crust formed previously is preferentially lost. That post-nebular volatilization was widespread is demonstrated by the non-chondritic Mn/Na ratio in all the small, differentiated, rocky bodies for which we have basaltic samples, including the Moon and Mars. The bulk silicate Earth (BSE) has chondritic Mn/Na, but shows several other compositional features in its pattern of depletion of volatile elements suggestive of non-chondritic fractionation. The whole-Earth Fe/Mg ratio is 2.1G0.1, significantly greater than the solar ratio of 1.9G0.1, implying net collisional erosion of approximately 10 per cent silicate relative to metal during the Earth's accretion. If this collisional erosion preferentially removed differentiated crust, the assumption of chondritic ratios among all RLEs in the BSE would not be valid, with the BSE depleted in elements according to their geochemical incompatibility. In the extreme case, the Earth would only have half the chondritic abundances of the highly incompatible, heat-producing elements Th, U and K. Such an Earth model resolves several geochemical paradoxes: the depleted mantle occupies the whole mantle, is completely outgassed in 40 Ar and produces the observed 4 He flux through the ocean basins. But the lower radiogenic heat production exacerbates the discrepancy with heat loss.

show abstract

“…The REE patterns for olivine and kirschsteinite in AdoR are basically parallel; however, olivine is depleted in all REEs relative to kirschsteinite. Our REE patterns for olivine and kirschsteinite in AdoR differ significantly from two AdoR olivine mineral separates (Ol-a and Ol-b) obtained by Ma et al (1977). Sc and Y abundances in AdoR olivine are nearly chondritic, with chondrite-normalized values of 1.0 and 3.8, respectively (Table 5).…”

Section: Trace Element Chemistry Of Silicates In Ador and Lew 86010mentioning

confidence: 89%

“…The purpose of this study was to investigate whether olivine and kirschsteinite in AdoR 1 The International Mineralogical Association's accepted name for the Ca-, Al-, Ti-rich pyroxene in angrites is subsilicic aluminian-ferrian diopside. Such pyroxene has also been termed aluminian-titanian-diopside (Mittlefehldt et al 1998), Al-Ti-diopside-hedenbergite (Mittlefehldt et al 2002), and fassaite by many workers (e.g., Prinz et al 1977;Ma et al 1977;Treiman 1989;Crozaz et al 1990;Lofgren et al 1992;Mikouchi et al 1995Mikouchi et al , 1996Mikouchi et al , 2001bFloss et al 2000Floss et al , 2001. For succinctness, we use the term fassaite throughout our paper to refer to the pyroxene found in angrites.…”

Section: Introductionmentioning

confidence: 99%

Thermal histories of angrite meteorites: Trace element partitioning among silicate minerals in Angra dos Reis, Lewis Cliff 86010, and experimental analogs

Fittipaldo

Jones

Shearer

2005

Meteoritics &Amp; Planetary Science

View full text Add to dashboard Cite

Abstract-We measured rare earth element (REE) abundances in selected silicate phases in the angrites Angra dos Reis (AdoR) and Lewis Cliff (LEW) 86010 in order to further clarify the thermal history of AdoR. We also carried out a preliminary experimental study designed to examine apparent REE partitioning between silicates (fassaite, olivine, kirschsteinite, and melt) in synthetic analogs of angrites under disequilibrium conditions at liquidus temperatures. Silicates in AdoR are homogeneous with respect to major, minor, and trace elements, which is consistent with the interpretation that AdoR underwent extensive subsolidus equilibration. REE distributions in olivine and kirschsteinite in AdoR are similar to those in LEW 86010 and are consistent with the formation of kirschsteinite by exsolution from olivine during cooling and/or annealing. There is no evidence for a disequilibrium trace element signature that could have been inherited from rapid cooling at liquidus temperatures. This is supported by our petrographic observations of the occurrence of kirschsteinite within olivine aggregates in AdoR. Olivine/kirschsteinite pairs in AdoR record closure temperatures around 600-650 °C.

show abstract

Genesis of the Angra dos Reis and other achondritic meteorites

Cited by 48 publications

References 34 publications

Asteroid 3628 Božněmcová: Covered with angrite-like basalts?

Asteroid 3628 Božněmcová: Covered with angrite-like basalts?

Collisional erosion and the non-chondritic composition of the terrestrial planets

Thermal histories of angrite meteorites: Trace element partitioning among silicate minerals in Angra dos Reis, Lewis Cliff 86010, and experimental analogs

Contact Info

Product

Resources

About