Chromite and olivine in type II chondrules in carbonaceous and ordinary chondrites: Implications for thermal histories and group differences

Johnson, Craig A.; Prinz, M.

doi:10.1016/0016-7037(91)90349-a

Cited by 70 publications

(82 citation statements)

References 45 publications

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“…However, it is also important to consider the effect of local environment around the chromian spinel and kinetic processes, such as diffusion-controlled crystallization. The usefulness of the morphology and composition of chromian spinel as a petrogenetic indicator also applies to chromian spinel that crystallizes fairly rapidly in chondrules from meteorites (Ramdohr 1973, Jones 1990, Johnson & Prinz 1991, McCoy et al 1991, Krot et al 1993 and in kimberlites (Pasteris 1983, Armstrong et al 1997. Although the crystals of chromian spinel are very small and few in number, this mineral has much to tell us about the magmatic history of a sample.…”

Section: Petrological Implications Of Morphology and Zoning Of Chromimentioning

confidence: 99%

Growth Forms and Composition of Chromian Spinel in Morb Magma: Diffusion-Controlled Crystallization of Chromian Spinel

Roeder

Poustovetov

Öskarsson

2001

The Canadian Mineralogist

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Microphenocrysts of chromian spinel in glass from an East Pacific Rise lava and three Icelandic subglacial lavas show a variety of complex skeletal, hopper, vermiform and chain textures. These grains of chromian spinel are larger than those found in most basalts. Many crystals show significant zoning in Cr/(Cr + Al), and the variation in Cr/(Cr + Al) with respect to Fe 2+ /(Fe 2+ + Mg) is distinctive for each sample. The four samples are relatively primitive, with between 9 and 10 wt.% MgO in the glass. One very distinctive texture, a core surrounded by a vermiform rim, has been interpreted by a number of researchers as a reaction texture caused either by changes in pressure or magma mixing. The variety of chromian spinel textures, including the vermiform rim, has been duplicated in an experimental run using the sample from the East Pacific Rise. The sample was held at 1225°C for 67 hours and then cooled slowly over 8 hours to 1147°C. We conclude that the vermiform texture and the other chromian spinel textures in the experimental run and the lavas are growth textures and not reaction textures. The change in growth habit that produces the vermiform rim is interpreted as diffusion-controlled growth, leading to what metallurgists refer to as cellular growth. Chromian spinel is susceptible to diffusion-controlled growth because of the very large difference in concentration of Cr in the melt (0.02-0.06 wt.% Cr 2 O 3 ) and in chromian spinel (30-50 wt.% Cr 2 O 3 ) at equilibrium. Although the chromian spinel in the glass of each natural sample shows a large variation in Cr/(Cr + Al), and thus was not in equilibrium with the bulk melt, its Fe 2+ / (Fe 2+ + Mg) may have been close to equilibrium with the bulk melt before quenching. The chromian spinel crystallized over a span of hours to days before a rapid water quench upon eruption. The complex textures and zoning probably reflect the turbulent conditions during passage of the magma toward the Earth's surface.Keywords: chromian spinel, chromite, basalt, texture, vermiform, hopper, diffusion-controlled crystallization. SOMMAIREDes microphénocristaux de spinelle chromifère sont présents dans une matrice vitreuse d'une lave basaltique provenant de la ride Est-Pacifique et de trois échantillons de coulées mises en place sous un glacier en Icelande. Ces cristaux contiennent une variété de textures complexes en entonnoir, vermiformes et en chaînes; ils sont plus grossiers que ceux qui caractérisent la plupart des basaltes. Plusieurs cristaux montrent une zonation importante en Cr/(Cr + Al), qui varie de façon distincte avec Fe 2+ /(Fe 2+ + Mg) dans chaque échantillon. Les quatre échantillons sont relativement primitifs, le verre contenant entre 9 et 10% (poids) de MgO. On a généralement interprété la présence d'un coeur entouré d'un liseré vermiforme comme résultat d'une réaction suite à des changements en pression ou à un mélange de magmas. La diversité texturale du spinelle chromifère, y inclus la bordure vermiforme, a été reproduite dans un série d'expériences f...

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Section: Petrological Implications Of Morphology and Zoning Of Chromimentioning

confidence: 99%

Growth Forms and Composition of Chromian Spinel in Morb Magma: Diffusion-Controlled Crystallization of Chromian Spinel

Roeder

Poustovetov

Öskarsson

2001

The Canadian Mineralogist

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“…It has been previously shown that Fe-Mg partitioning (KO = (Fe/Mg)SPi"e'/(Fe/Mg)olivine) between coexisting olivine and Crspinel in type41 chondrules is a sensitive indicator of their thermal processing (Johnson and Prinz, 1991). Type-I1 chondrules in MAC 881 07 display KO values characteristic of equilibration -1400 "C ( Fig.…”

Section: Evidence For Growth Of Fayalite and Hedenbergite During Low-mentioning

confidence: 99%

Evidence for low‐temperature growth of fayalite and hedenbergite in MacAlpine Hills 88107, an ungrouped carbonaceous chondrite related to the CM‐CO clan

Krot

Brearley

Petaev

et al. 2000

Meteorit & Planetary Scien

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Abstract-The carbonaceous chondrite MacAlpine Hills (MAC) 88 107 has bulk composition and mineralogy that are intermediate between those of CO and CM chondrites. This meteorite experienced minor alteration and a low degree of thermal metamorphism (petrologic type 3.1) and escaped post-accretional brecciation. The alteration resulted in the formation of fayalite (Fago-loo), Al-free hedenbergite (-Fs~oWo50), phyllosilicates (saponite-serpentine intergrowths), magnetite, and Ni-bearing sulfides (pyrrhotite and pentlandite). Fayalite and hedenbergite typically occur as veins, which start at the opaque nodules in the chondrule peripheries, crosscut fine-grained rims and either terminate at the boundaries with the neighboring fine-grained rims or continue as layers between these rims. These observations suggest that fayalite and hedenbergite crystallized after accretion and compaction of the fine-grained rims. Fayalite also overgrows isolated forsteritic (Fa]-5) and fayalitic (Fa204 olivine grains without any evidence for Fe-Mg interdiffusion; it also replaces massive magnetite-sulfide grains. The initial 53Md55Mn ratio of (1.58 2 0.26) x 10-6 in the MAC 88107 fayalite corresponds to an age difference between the formation of fayalite and refractory inclusions in Allende of either -9 or 18 Ma, depending upon the value of the solar system initial abundance of 53Mn used in age calculations.Formation of secondary fayalite and hedenbergite requires mobilization and transport of Ca, Si, and Fe either through a high-temperature gaseous phase (Hua and Buseck, 1995) or low-temperature aqueous solution (Krot et al., 1998a,b). The high-temperature nebular model for the origin of fayalite (HIM and Buseck, 1995) fails to explain (a) formation of fayalite-hedenbergite assemblages after accretion of fine-grained rims that lack any evidence for high-temperature processing; (b) extreme fractionation of refractory lithophile elements of similar volatility, Ca and Al, in hedenbergite; and (c) absence of Fe-Mg interdiffusion along fayaliteforsterite boundaries. We conclude that fayalite and hedenbergite in MAC 88107 formed during late-stage, lowtemperature (approximately 150-200 "C) aqueous alteration. The data for MAC 88 107 extend the evidence for an early onset of aqueous activity on chondrite parent bodies and reinforce the conclusion that liquid water played an important role in the chemical and mineralogical evolution of the first chondritic planetesimals.

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“…However, the spinel composition cannot be used to distinguish the subgroups between types 3.0 and 3.3. The olivine-spinel geothermometer gives igneous crystallization temperatures >1000 °C for chondrules in types 3.0-3.3, whereas for chondrules in types 3.5-3.9 it gives metamorphic temperatures of 440-650 °C (Johnson and Prinz 1991;Kimura et al 2006b). Therefore, diffusion barely took place in the spinel of type 3.0-3.3 chondrites.…”

Section: Other Chondritesmentioning

confidence: 99%

Fe‐Ni metal in primitive chondrites: Indicators of classification and metamorphic conditions for ordinary and CO chondrites

Kimura

Grossman

Weisberg

2008

Meteorit & Planetary Scien

156

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Metal in other type 3 chondrites is composed of fine-to coarse-grained aggregates of kamacite and Ni-rich metal, resulting from metamorphism in the parent body. We found that the number density of Ni-rich grains in metal (number of Ni-rich grains per unit area of metal) in chondrules systematically decreases with increasing petrologic type. Thus, Fe-Ni metal is a highly sensitive recorder of metamorphism in ordinary and carbonaceous chondrites, and can be used to distinguish petrologic type and identify the least thermally metamorphosed chondrites. Among the known ordinary and CO chondrites, Semarkona is the most primitive. The range of metamorphic temperatures were similar for type 3 ordinary and CO chondrites, despite them having different parent bodies. Most Fe-Ni metal in Acfer 094 is martensite, and it preserves primary features. The degree of metamorphism is lower in Acfer 094, a true type 3.00 chondrite, than in Semarkona, which should be reclassified as type 3.01.

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Chromite and olivine in type II chondrules in carbonaceous and ordinary chondrites: Implications for thermal histories and group differences

Cited by 70 publications

References 45 publications

Growth Forms and Composition of Chromian Spinel in Morb Magma: Diffusion-Controlled Crystallization of Chromian Spinel

Growth Forms and Composition of Chromian Spinel in Morb Magma: Diffusion-Controlled Crystallization of Chromian Spinel

Evidence for low‐temperature growth of fayalite and hedenbergite in MacAlpine Hills 88107, an ungrouped carbonaceous chondrite related to the CM‐CO clan

Fe‐Ni metal in primitive chondrites: Indicators of classification and metamorphic conditions for ordinary and CO chondrites

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