Chondrule size and related physical properties: A compilation and evaluation of current data across all meteorite groups

Friedrich, J. M.; Weisberg, M. K.; Ebel, D. S.; Biltz, Alison E.; Corbett, Bernadette M.; Iotzov, Ivan V.; Khan, Wajiha S.; Wolman, Matthew D.

doi:10.1016/j.chemer.2014.08.003

Cited by 149 publications

(141 citation statements)

References 94 publications

(273 reference statements)

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“…The average chondrule size (~500 μm) is closest to that of mean LL chondrites (550 μm; table 7 of Friedrich et al. ). The mean olivine composition (Fa 28.1 ± 1.8; PMD = 5.1; n = 16) and mean kamacite Co content (1.5 ± 0.9 wt%; n = 7) are well within the equilibrated LL chondrite ranges (Fa 26.6–32.4; 1.42–37.0 wt% Co; Rubin ).…”

Section: Resultsmentioning

confidence: 61%

NWA 10214—An LL3 chondrite breccia with an assortment of metamorphosed, shocked, and unique chondrite clasts

Rubin

Breen

Isa

et al. 2016

Meteorit & Planetary Scien

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NWA 10214 is an LL3‐6 breccia containing ~8 vol% clasts including LL5, LL6, and shocked‐darkened LL fragments as well as matrix‐rich Clast 6 (a new kind of chondrite). This clast is a dark‐colored, subrounded, 6.1 × 7.0 mm inclusion, consisting of 60 vol% fine‐grained matrix, 32 vol% coarse silicate grains, and 8 vol% coarse opaque grains. The large chondrules and chondrule fragments are mainly Type IB; one small chondrule is Type IIA. Also present are one 450 × 600 μm spinel‐pyroxene‐olivine CAI and one 85 × 110 μm AOI. Clast 6 possesses a unique set of properties. (1) It resembles carbonaceous chondrites in having relatively abundant matrix, CAIs, and AOIs; the clast's matrix composition is close to that in CV3 Vigarano. (2) It resembles type‐3 OC in its olivine and low‐Ca pyroxene compositional distributions, and in the Fe/Mn ratio of ferroan olivine grains. Its mean chondrule size is within 1σ of that of H chondrites. The O‐isotopic compositions of the chondrules are in the ordinary‐ and R‐chondrite ranges. (3) It resembles type‐3 enstatite chondrites in the minor element concentrations in low‐Ca pyroxene grains and in having a high low‐Ca pyroxene/olivine ratio in chondrules. Clast 6 is a new variety of type‐3 OC, somewhat more reduced than H chondrites or chondritic clasts in the Netschaevo IIE iron; the clast formed in a nebular region where aerodynamic radial drift processes deposited a high abundance of matrix material and CAIs. A chunk of this chondrite was ejected from its parent asteroid and later impacted the LL body at low relative velocity.

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Section: Resultsmentioning

confidence: 61%

NWA 10214—An LL3 chondrite breccia with an assortment of metamorphosed, shocked, and unique chondrite clasts

Rubin

Breen

Isa

et al. 2016

Meteorit & Planetary Scien

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“…), which is comparable to the value from R chondrites (400 μm), but differs from the values of CH (20 μm), CO (150 μm), CB (200 μm), CR (700 μm), and CV/CK (900 μm) chondrites, as well as chondrule average diameters from ordinary chondrites (450–550 μm) (Friedrich et al. ). Of Y‐82094 chondrules, 99.1% are FeO‐poor (defined as those with Mg# silicate >90; Mg# = mole% MgO/[MgO + FeO]); FeO‐rich chondrules (Mg# silicate <90) are sparse (0.9%).…”

Section: Introductionmentioning

confidence: 49%

Oxygen isotope characteristics of chondrules from the Yamato‐82094 ungrouped carbonaceous chondrite: Further evidence for common O‐isotope environments sampled among carbonaceous chondrites

Tenner

Kimura

Kita

2016

Meteorit & Planetary Scien

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High‐precision secondary ion mass spectrometry (SIMS) was employed to investigate oxygen three isotopes of phenocrysts in 35 chondrules from the Yamato (Y) 82094 ungrouped 3.2 carbonaceous chondrite. Twenty‐one of 21 chondrules have multiple homogeneous pyroxene data (∆17O 3SD analytical uncertainty: 0.7‰); 17 of 17 chondrules have multiple homogeneous pyroxene and plagioclase data. Twenty‐one of 25 chondrules have one or more olivine data matching coexisting pyroxene data. Such homogeneous phenocrysts (1) are interpreted to have crystallized from the final chondrule melt, defining host O‐isotope ratios; and (2) suggest efficient O‐isotope exchange between ambient gas and chondrule melt during formation. Host values plot within 0.7‰ of the primitive chondrule mineral (PCM) line. Seventeen chondrules have relict olivine and/or spinel, with some δ17O and δ18O values approaching −40‰, similar to CAI or AOA‐like precursors. Regarding host chondrule data, 22 of 34 have Mg#s of 98.8–99.5 and ∆17O of −3.9‰ to −6.1‰, consistent with most Acfer 094, CO, CR, and CV chondrite chondrules, and suggesting a common reduced O‐isotope reservoir devoid of 16O‐poor H2O. Six Y‐82094 chondrules have ∆17O near −2.5‰, with Mg#s of 64–97, consistent with lower Mg# chondrules from Acfer 094, CO, CR, and CV chondrites; their signatures suggest precursors consisting of those forming Mg# ~99, ∆17O: −5‰ ± 1‰ chondrules plus 16O‐poor H2O, at high dust enrichments. Three type II chondrules plot slightly above the PCM line, near the terrestrial fractionation line (∆17O: ~+0.1‰). Their O‐isotopes and olivine chemistry are like LL3 type II chondrules, suggesting they sampled ordinary chondrite‐like chondrule precursors. Finally, three Mg# >99 chondrules have ∆17O of −6.7‰ to −8.1‰, potentially due to 16O‐rich refractory precursor components. The predominance of Mg# ~99, ∆17O: −5‰ ± 1‰ chondrules and a high chondrule‐to‐matrix ratio suggests bulk Y‐82094 characteristics are closely related to anhydrous dust sampled by most carbonaceous chondrite chondrules.

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“…It is worth noting in this regard that in their numerous publications on iron droplets, Friedrich et al, (2015) support the idea that these grains were formed via condensation, that is, are nebular in origin. There is no logical reason why the reduction of oxides (equilibrium reaction (1)) could not also be associated with the condensation processes occurring in a cooling gas of cosmic composition.…”

Section: Argument 8: Chromium Copper and Dual-concentration Valuesmentioning

confidence: 89%

“…In the case of equilibrium reaction (1), age determination begins with the mobilization process itself; for equilibrium reaction (2), age determination begins prior to mobilization, as the iron was already separate from the silicate phase before mobilization began. Information on the origins of the metal phase in chondrites has been provided by Ebihara (1996, 1997), Davis and Richter (2014) and Friedrich et al (2015). Further insight is likely to be gained if it can be shown that the series ataxites, Of, Off, Om, Ogg, H, Og (see Argument 7) is connected to trends in the absolute ages of these meteorites.…”

Section: Argument 13: Cosmochronologymentioning

confidence: 99%

Formation of nickel–iron meteorites by chemical fluid transport

Schrön¹

2017

ScienceOpen Research

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The deposition of solid material from the gas phase via chemical vapor transport (CVT) is a well-known process of industrial and geochemical relevance. There is strong evidence that this type of thermodynamically driven chemical transport reaction plays a significant role in certain natural processes. This article presents detailed evidence that CVT is a highly plausible mechanism for the formation of iron meteorites. In this study, naturally occurring CVT is referred to as "chemical fluid transport" (CFT) and the end products deposited from the gas phase as "fluidites."Treating iron meteorites as cosmic fluidites enables simple solutions to be found to the problem of how they formed and to numerous related and in some cases unresolved questions. This study is based on a thermodynamic trend analysis of solid-gas equilibrium reactions involving chlorine-and fluorinecontaining compounds of 42 chemical elements that include a systematic examination of reaction dominance switching behavior. In order to assess the transport behavior of the individual elements, the reaction-conditioned pressures p MeX were calculated from the equilibrium constants. For a selected group of minerals, the relative propensity of these minerals to deposit from the gas phase was then derived from the equilibrium constants. The study shows that octahedrites, hexahedrites and ataxites formed as a result of the transport of metal chlorides and fluorides (CFT) during accretion within the solar nebula. Siderophile elements are characterized by the similarities in their chemical transport properties. These chemical properties of the elements, expressed in the form of the reaction-conditioned pressure, play a key role in determining the chemical composition of iron meteorites. The mobilization process that leads to the formation of the gaseous metal halides MeX includes the reduction of oxides. The deposition of nickel-iron bodies occurs via back reaction after the transport of the gaseous halides. The back reaction leads to the thermodynamically favored deposition of schreibersite before troilite and of troilite before kamacite/taenite. The deposition temperature of octahedrites and hexahedrites lies below the temperature at which Widmanstätten patterns would be destroyed, while that of ataxites lies slightly above. Similarly, the occurrence of thermally instable cohenite in meteorites provides further support for the fluidite character of irons.The variation in the trace element concentrations in iron meteorites is explained by enrichment and depletion mechanisms in the gas phase. The striking correlation between gallium and germanium abundances in iron meteorites is the result of similarities regarding the mobilization phase and the reaction dominance switching behavior of both elements, and crystal isomorphism.These findings are supported by numerous arguments that provide evidence for the CFT model. The occurrence of the mineral lawrencite FeCl 2 in meteorites is interpreted as an indication of the effectiveness of the chemical transp...

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Chondrule size and related physical properties: A compilation and evaluation of current data across all meteorite groups

Abstract: Please cite this article in press as: Friedrich, J.M., et al., Chondrule size and related physical properties: A compilation and evaluation of current data across all meteorite groups. Chemie Erde -Geochemistry (2014), http://dx.

Cited by 149 publications

References 94 publications

NWA 10214—An LL3 chondrite breccia with an assortment of metamorphosed, shocked, and unique chondrite clasts

NWA 10214—An LL3 chondrite breccia with an assortment of metamorphosed, shocked, and unique chondrite clasts

Oxygen isotope characteristics of chondrules from the Yamato‐82094 ungrouped carbonaceous chondrite: Further evidence for common O‐isotope environments sampled among carbonaceous chondrites

Formation of nickel–iron meteorites by chemical fluid transport

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