Condensation of CaOMgOAl2O3SiO2 liquids from cosmic gases

Yoneda, Shigekazu; Grossman, Lawrence

doi:10.1016/0016-7037(95)00214-k

Cited by 238 publications

(225 citation statements)

References 43 publications

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“…Moreover, the occurrence of the fassaite rims on perovskites enclosed in melilite suggests a formation sequence in order of perovskite, fassaite, and melilite. This is inconsistent with the sequence of condensation in the nebula, because fassaite is expected to condense at ~180 K lower than melilite (Yoneda and Grossman 1995).…”

Section: Fassaite Rims On Perovskitementioning

confidence: 82%

Fassaites in compact type A Ca‐Al‐rich inclusions in the Ningqiang carbonaceous chondrite: Evidence for partial melting in the nebula

Lin

Kimura

Wang

2003

Meteorit & Planetary Scien

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Abstract-Fassaite is a major component of Ca-Al-rich inclusions (CAIs) of Types B and C that crystallized from liquids. In contrast, this mineral is rarely reported in Type A inclusions and has been much less studied. In this paper, we report highly Ti-, Al-enriched fassaite that occurs as rims on perovskite in two compact Type A inclusions from the Ningqiang meteorite. In addition, one of the inclusions contains an euhedral grain of Sc-fassaite (16.4 wt% Sc 2 O 3 ) isolated in melilite. The occurrence and mineral chemistry of the fassaite rims can be explained by a reaction of pre-existing perovskite with CAI melts. Hence, such rims may serve as an indicator for partial melting of Type A inclusions. The Sc-fassaite is probably a relict grain. A third spherical CAI contains several euhedral grains of V-fassaite (4.8-5.4 wt% V 2 O 3 ) enclosed in a melilite fragment. The high V content of fassaite cannot be related to any Fremdlinge, magnetite, or metallic Fe-Ni, because these phases are absent in the inclusion. In the same CAI, other fassaites intergrow with spinel and minor perovskite, filling voids inside of the melilite and space adjacent to the Wark-Lovering rim. The fassaite intergrown with spinel is almost V-free. The coexistence of two types of fassaite suggests that this CAI has not been completely melted.

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Section: Fassaite Rims On Perovskitementioning

confidence: 82%

Fassaites in compact type A Ca‐Al‐rich inclusions in the Ningqiang carbonaceous chondrite: Evidence for partial melting in the nebula

Lin

Kimura

Wang

2003

Meteorit & Planetary Scien

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“…f O 2 very close to that of a system of solar composition at 1500K. For OC, the anhydrous chondritic dust component defined by Yoneda and Grossman (1995), enrichment in dust relative to gas by factors of 10 and 100 compared to solar composition results in enhancements in Accordingly, to model condensation at a dust enrichment plausibly relevant to CAI formation, a set of condensation calculations identical to that described above was carried out for a system enriched in OC dust by a factor of 10.…”

Section: Condensation Paths For Solar Compositionmentioning

confidence: 99%

Primordial compositions of refractory inclusions

Grossman

Simon

Vinai

et al. 2008

Geochimica et Cosmochimica Acta

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Bulk chemical and oxygen, magnesium and silicon isotopic compositions were measured for each of 17 Types A and B refractory inclusions from CV3 chondrites. After bulk chemical compositions were corrected for non-representative sampling in the laboratory, the Mg and Si isotopic compositions of each inclusion were used to calculate its original chemical composition assuming that the heavy-isotope enrichments of these elements are due to Rayleigh fractionation that accompanied their evaporation from CMAS liquids. The resulting pre-evaporation chemical compositions are consistent with those predicted by equilibrium thermodynamic calculations for high-temperature nebular condensates but only if different inclusions condensed from nebular regions that ranged in total pressure from 10 -6 to 10 -1 bar, regardless of whether they formed in a system of solar composition or in one enriched in OC dust relative to gas by a factor of ten relative to solar composition. This is similar to the range of total pressures predicted by dynamic models of the solar nebula for regions whose temperatures are in the range of silicate condensation temperatures. Alternatively, if departure from equilibrium condensation and/or non-representative sampling of condensates in the nebula occurred, the inferred range of total pressure could be smaller. Simple kinetic modeling of evaporation successfully reproduces observed chemical compositions of most inclusions from their inferred pre-evaporation compositions, suggesting that closed-system isotopic exchange processes did not have a significant effect on their isotopic compositions. Comparison of pre-evaporation compositions with observed ones indicates that 80% of the enrichment in refractory CaO + Al 2 O 3 relative to more volatile MgO + SiO 2 is due to initial condensation and 20% due to subsequent evaporation for both Type A and Type B inclusions.

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“…Another group of "intermediate" objects are the Type C CAIs, which are rare relative to other CAI varieties and which have been little studied (Wark, 1987). Their bulk compositions are close to those of many Al-rich chondrules and, like the latter, deviate significantly from the predictions of equilibrium condensation of a hot solar gas (Beckett and Grossman, 1988;Yoneda and Grossman, 1995;see discussion by MacPherson and Huss, 2005).…”

Section: Introductionmentioning

confidence: 99%