Use of a CO2 laser to prepare chondrule-like spherules from supercooled molten oxide and silicate droplets

Nelson, Lloyd S.; Blander, M.; Skaggs, S. R.; Keil, K.

doi:10.1016/0012-821x(72)90133-1

Cited by 58 publications

(18 citation statements)

References 25 publications

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“…Even slow cooling of such droplets would be expected to yield quench textures. Calculations by Nelson et al (1972) suggest that, in a completely molten droplet, the absence of crystal nucleii could permit significant degrees of undercooling even at much slower cooling rates than those used in their experiments, leading to rapid crystallization and therefore textures similar to those ofquenched spherules. Slow cooling would also allow extensive evaporation from the melt, which leads to problems as described below.…”

Section: Solid/gas Distribution Coefficientsmentioning

confidence: 99%

A hibonite‐corundum inclusion from Murchison: A first‐generation condensate from the solar nebula

Simon

Davis

Grossman

et al. 2002

Meteorit & Planetary Scien

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Abstract-Through freeze-thaw disaggregation of the Murchison (CM) carbonaceous chondrite, we have recovered a~90 x 75 ,um refractory inclusion that consists of corundum and hibonite with minor perovskite. Corundum occurs as small (~IO ,um), rounded grains enclosed in hibonite laths (~I 0 ,umwide and 30--40 ,umlong) throughout the inclusion. Perovskite predominantly occurs near the edge ofthe inclusion. The crystallization sequence inferred petrographically--corundum followed by hibonite followed by perovskite-is that predicted for the first phases to form by equilibrium condensation from a solar gas for ptot :s; 5 x I 0-3 atm. In addition, the texture of the inclusion, with angular voids between subhedral hibonite laths and plates, is also consistent with formation of the inclusion by condensation. Hibonite has heavy rare earth element (REE) abundances of~40 x CI chondrites, light REE abundances~20 x CI chondrites, and negative Eu anomalies. The chondritenormalized abundance patterns, especially one for a hibonite-perovskite spot, are quite similar to the patterns of calculated solid/gas partition coefficients for hibonite and perovskite at 10-3 atm and are not consistent with formation ofthe inclusion by closed-system fractional crystallization. In contrast with the features that are consistent with a condensation origin, there are problems with any model for the formation of this inclusion that includes a molten stage, relic grains, or volatilization. If thermodynamic models ofequilibrium condensation are correct, then this inclusion formed at pressures <5 x 10-3 atm, possibly with enrichments «1 OOOx) in CI dust relative to gas at low pressures (below 10--4 atm). Both hibonite and corundum have 0 17 0 =0 18 0 = -50%0, indicating formation from an 160-rich source. The inclusion does not contain radiogenic 26Mg and apparently did not contain live 26AI when it formed. If the short-lived radionuclides were formed in a supernova and injected into the early solar nebula, models ofthis process suggest that 26AI-free refractory inclusions such as this one formed within the first~6 x 10 5 years of nebular collapse.

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Section: Solid/gas Distribution Coefficientsmentioning

confidence: 99%

A hibonite‐corundum inclusion from Murchison: A first‐generation condensate from the solar nebula

Simon

Davis

Grossman

et al. 2002

Meteorit & Planetary Scien

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“…( 1973), Nelson et al ( 1972) showed that A1203 droplets solidify with spherulitic textures as a result of being subcooled by amounts comparable to those in the work of Keil et al (1973). We have seen that at least this degree of subcooling would have been required for BB-5 to condense as a metastable liquid instead of corundum and hibonite, but no textures even remotely resembling those of Nelson et al (1972) are present in BB-5.…”

Section: Liquid Originmentioning

confidence: 77%

“…We have seen that at least this degree of subcooling would have been required for BB-5 to condense as a metastable liquid instead of corundum and hibonite, but no textures even remotely resembling those of Nelson et al (1972) are present in BB-5. We conclude from both theoretical and textural arguments that formation of BB-5 as a metastable liquid condensate is highly improbable.…”

Section: Liquid Originmentioning

confidence: 94%

A corundum-rich inclusion in the Murchison carbonaceous chondrite

Bar‐Matthews

Hutcheon

MacPherson

et al. 1982

Geochimica et Cosmochimica Acta

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“…An experimental insight into these radiation-structure interactions is of interest to tailor formation of these structures and to translate this knowledge in order to understand the evolution of the solar system. The first experiments that used the infrared radiation from a laser to form molten chondrule-like objects were carried out by Nelson et al (1972), in which radial textures of pyroxene were reproduced. Droplets of alumina, enstatite, forsterite, enstatite-albite, forsterite-albite and mixtures were melted by using a CO 2 laser and the initial temperatures of the melts were measured using an optical pyrometer.…”

Section: Previous Workmentioning

confidence: 99%

Experimental chondrules by melting samples of olivine, clays and carbon with a CO2 laser

Cruz¹,

Gutiérrez²,

Viñas³

et al. 2015

BSGM

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Chondrules are the major constituents of chondritic meteorites; however, their origin is still an enigma for meteoritic science. In this work we report the results of melting minerals to experimentally generate objects similar to chondrules. The degree of fusion of olivine appears to be an important factor in determining the width of the bars in samples with barred-type olivine (BO) chondrules. On the other hand, the contribution of clays and carbon (possible precursor grains) is an important factor in those experiments where the melted samples showed porphyritic texture.Keywords: experimental chondrules, chondrites, CO 2 laser. Resumen Los condros son los constituyentes principales de las meteoritas condríticas. Sin embargo, su formación sigue siendo un enigma para la ciencia de la meteorítica. En este trabajo se reportan los resultados de la fusión de minerales para obtener fundidos tipo condro. El grado de fusión del olivino es un factor importante para determinar el ancho de las barras de las muestras tipo condros barrados de olivino (BO). Por otra parte, la contribución de arcillas y carbón (posibles componentes de los granos precursores) es un factor importante en los experimentos en los que los fundidos generados tienen textura porfídica.Palabras clave: condros experimentales, condritas, láser de CO 2 .

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Use of a CO2 laser to prepare chondrule-like spherules from supercooled molten oxide and silicate droplets

Cited by 58 publications

References 25 publications

A hibonite‐corundum inclusion from Murchison: A first‐generation condensate from the solar nebula

A hibonite‐corundum inclusion from Murchison: A first‐generation condensate from the solar nebula

A corundum-rich inclusion in the Murchison carbonaceous chondrite

Experimental chondrules by melting samples of olivine, clays and carbon with a CO2 laser

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