Major and trace elements in the Allende meteorite

Martin, Philip; Mason, Brian

doi:10.1038/249333a0

Cited by 97 publications

(30 citation statements)

References 7 publications

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“…The main fractionation patterns were recognized very early as a result of studies of Allende CAIs (e.g., Grossman, 1973;Grossman and Ganapathy, 1976a,b;Martin and Mason, 1974; Mason and Martin, 1977;Tanaka and Masuda, 1973) and later found to occur in CAIs from other chondrites and chondrite types as well (e.g., Fahey et al, 1987a;Guan et al, 2002;Hinton et al, 1988;Ireland, 1990;Ireland et al, 1988;Russell et al, 1998). Consider first the REEs.…”

Section: Trace Elementsmentioning

confidence: 96%

Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

MacPherson

2014

Treatise on Geochemistry

106

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Section: Trace Elementsmentioning

confidence: 96%

Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

MacPherson

2014

Treatise on Geochemistry

106

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“…There also exists in Allende a class of objects, finegrained inclusions, in which refractory elements are severaly fractionated from one another, both in individual inclusions [13] and in groups of inclusions as a whole [14,19]. Although these are easily distinguished on the basis of their pink or purple color and soft, sugary consistency from coarse-grained ones, Grossman and Ganapathy [19] discovered one inclusion among their group of ten so-called coarse-grained inclusions which had all the physical attributes of a coarse-grained one but the characteristic, peculiar fractionation pattern of a fine-grained one.…”

Section: Proposed Experiments To Measure the Initial 2~pu/ 2 3 S U Ratiomentioning

confidence: 99%

“…Many trace element studies [6,[12][13][14][15][16][17][18][19][20][21] have demonstrated enrichment of the inclusions in these refractory elements and their depletion in elements which are more volatile in the solar nebula. The concentration of any particular refractory trace element and, often, the ratio of one refractory to another vary widely from inclusion to inclusion.…”

Section: Composition Of Allende Inclusionsmentioning

confidence: 99%

The case for an unfractionated244Pu/238U ratio in high-temperature condensates

Ganapathy

Grossman

1976

Earth and Planetary Science Letters

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The coarse-g~ained, Ca-rich inclusions in the AUende meteorite are the highest-temperature condensates from the cooling solar nebula and, as such, the oldest solid objects in the solar system. All refractory elements with condensalion points above the accretion temperature of the inclusions whose eoneentrarions in them have been measured are seen to be present in the inclusions in unfractionated proportion to one another relative to C1 ehondrites when data ate averaged for a large number of inclusions. Observational data for U and theoretical data for both U and Pu'suggest that these elements exhibited refractory behavior in the solar nebula. An experiment is proposed in which fissiogenic Xe and U contents are measured in a suite of these inclusions to obtain the 244pu/238U ratio of the solar system at the time of initial condensation with an uncertainty of + 15%.

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“…Such patterns were first identified by Tanaka and Masuda (1973) in a finegrained, spinel-rich CAI from Allende, and it was observed subsequently that similar inclusions in CV chondrites commonly are characterized by such trace element patterns. Boynton (1975) and, later, Davis and Grossman (1979) showed that these so called group II (Martin and Mason 1974) trace element patterns can only be formed by condensation; they cannot be vaporization residues. Thus, CAIs with group II trace element patterns remain one of the strongest kinds of evidence for condensation in the early solar nebula.…”

Section: Introductionmentioning

confidence: 99%

Fine‐grained, spinel‐rich inclusions from the reduced CV chondrites Efremovka and Leoville: I. Mineralogy, petrology, and bulk chemistry

Krot

MacPherson

Ulyanov

et al. 2004

Meteorit & Planetary Scien

110

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Abstract-Fine-grained, spinel-rich inclusions in the reduced CV chondrites Efremovka and Leoville consist of spinel, melilite, anorthite, Al-diopside, and minor hibonite and perovskite; forsterite is very rare. Several CAIs are surrounded by forsterite-rich accretionary rims. In contrast to heavily altered fine-grained CAIs in the oxidized CV chondrite Allende, those in the reduced CVs experienced very little alteration (secondary nepheline and sodalite are rare). The Efremovka and Leoville fine-grained CAIs are 16 O-enriched and, like their Allende counterparts, generally have volatility fractionated group II rare earth element patterns. Three out of 13 fine-grained CAIs we studied are structurally uniform and consist of small concentrically zoned nodules having spinel ± hibonite ± perovskite cores surrounded by layers of melilite and Al-diopside. Other fine-grained CAIs show an overall structural zonation defined by modal mineralogy differences between the inclusion cores and mantles. The cores are melilite-free and consist of tiny spinel ± hibonite ± perovskite grains surrounded by layers of anorthite and Al-diopside. The mantles are calcium-enriched, magnesium-depleted and coarsergrained relative to the cores; they generally contain abundant melilite but have less spinel and anorthite than the cores. The bulk compositions of fine-grained CAIs generally show significant fractionation of Al from Ca and Ti, with Ca and Ti being depleted relative to Al; they are similar to those of coarsegrained, type C igneous CAIs, and thus are reasonable candidate precursors for the latter. The finegrained CAIs originally formed as aggregates of spinel-perovskite-melilite ± hibonite gas-solid condensates from a reservoir that was 16 O-enriched but depleted in the most refractory REEs. These aggregates later experienced low-temperature gas-solid nebular reactions with gaseous SiO and Mg to form Al-diopside and ±anorthite. The zoned structures of many of the fine-grained inclusions may be the result of subsequent reheating that resulted in the evaporative loss of SiO and Mg and the formation of melilite. The inferred multi-stage formation history of fine-grained inclusions in Efremovka and Leoville is consistent with a complex formation history of coarse-grained CAIs in CV chondrites.

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Major and trace elements in the Allende meteorite

Cited by 97 publications

References 7 publications

Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

The case for an unfractionated244Pu/238U ratio in high-temperature condensates

Fine‐grained, spinel‐rich inclusions from the reduced CV chondrites Efremovka and Leoville: I. Mineralogy, petrology, and bulk chemistry

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