Fe isotope fractionation in iron meteorites: New insights into metal-sulphide segregation and planetary accretion

Williams, Helen M.; Markowski, A.; Quitté, G.; Halliday, Alex N.; Teutsch, Nadya; Levasseur, S.

doi:10.1016/j.epsl.2006.08.013

Cited by 76 publications

(77 citation statements)

References 42 publications

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“…Chondrules display the largest variation, metals and sulphides show smaller variations (Needham et al 2009). As shown by Williams et al (2006) Fe isotope differences between metal and troilite are in the range of 0.5 ‰-the metal phase being heavier than the sulfide phase troilite, potentially reflecting equilibrium fractionations.…”

Section: Meteoritesmentioning

confidence: 97%

Isotope Fractionation Processes of Selected Elements

Hoefs

2015

Stable Isotope Geochemistry

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Section: Meteoritesmentioning

confidence: 97%

Isotope Fractionation Processes of Selected Elements

Hoefs

2015

Stable Isotope Geochemistry

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“…Nickel isotopes may have been fractionated as a result of the interaction of a metallic melt with a S and/or P-rich melt during core crystallization. Furthermore, Fe isotopes are fractionated between metal, phosphide (i.e., schreibersite), and sulfide (i.e., troilite) in pallasites (Poitrasson et al 2005;Weyer et al 2005) and between metal and sulfide in iron meteorites (Williams et al 2006). Crystallization followed by slow subsolidus cooling of metallic and non-metallic phases in IIIAB irons may have fractionated Ni isotopes in a similar manner.…”

Section: Nickel Isotopesmentioning

confidence: 99%

“…F Fe = δ 56/54 /2. Circles = this study; squares = Zhu et al 2001;Kehm et al 2003;Schoenberg et al 2006;Williams et al 2006; hatched area = range reported by Mullane et al (2005). Although the observed isotopic fractionations in Toluca are consistent with kinetic effects (especially given the role of diffusion in formation of the Widmanstätten pattern) equilibrium fractionation cannot be ruled out.…”

Section: Isotopic Fractionation Between Kamacite and Taenitementioning

confidence: 99%

Mass‐dependent fractionation of nickel isotopes in meteoritic metal

Cook

Clayton

Dauphas

et al. 2007

Meteorit & Planetary Scien

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available online at http://meteoritics.org Abstract-We measured nickel isotopes via multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) in the bulk metal from 36 meteorites, including chondrites, pallasites, and irons (magmatic and non-magmatic). The Ni isotopes in these meteorites are mass fractionated; the fractionation spans an overall range of ≈0.4‰ amu −1 . The ranges of Ni isotopic compositions (relative to the SRM 986 Ni isotopic standard) in metal from iron meteorites (≈0.0 to ≈0.3‰ amu −1 ) and chondrites (≈0.0 to ≈0.2‰ amu −1 ) are similar, whereas the range in pallasite metal (≈−0.1 to 0.0‰ amu −1 ) appears distinct. The fractionation of Ni isotopes within a suite of fourteen IIIAB irons (≈0.0 to ≈0.3‰ amu −1 ) spans the entire range measured in all magmatic irons. However, the degree of Ni isotopic fractionation in these samples does not correlate with their Ni content, suggesting that core crystallization did not fractionate Ni isotopes in a systematic way. We also measured the Ni and Fe isotopes in adjacent kamacite and taenite from the Toluca IAB iron meteorite. Nickel isotopes show clearly resolvable fractionation between these two phases; kamacite is heavier relative to taenite by ≈0.4‰ amu −1 . In contrast, the Fe isotopes do not show a resolvable fractionation between kamacite and taenite. The observed isotopic compositions of kamacite and taenite can be understood in terms of kinetic fractionation due to diffusion of Ni during cooling of the Fe-Ni alloy and the development of the Widmanstätten pattern. Mass-dependent fractionation of nickel isotopes in meteoritic metal

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“…Because of dilution effects, one would expect lower kinetic isotope fractionation for Fe compared to Ni, as observed. However, at 500 °C, one cannot completely rule out the possibility that equilibrium fractionation contributed to the overall isotopic fractionation that is measured (e.g., Polyakov and Mineev 2000;Poitrasson et al 2005;Williams et al 2006;Schuessler et al 2007).…”

Section: Observationsmentioning

confidence: 99%

Diffusion‐driven kinetic isotope effect of Fe and Ni during formation of the Widmanstätten pattern

Dauphas

2007

Meteorit & Planetary Scien

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Abstract-Iron meteorites show resolvable Fe and Ni isotopic fractionation between taenite and kamacite. For Toluca (IAB), the isotopic fractionations between the two phases are around +0.1‰/amu for Fe and −0.4‰/amu for Ni. These variations may be due to i) equilibrium fractionation, ii) differences in the diffusivities of the different isotopes, or iii) a combination of both processes. A computer algorithm was developed in order to follow the growth of kamacite out of taenite during the formation of the Widmanstätten pattern as well as calculate the fractionation of Fe and Ni isotopes for a set of cooling rates ranging from 25 to 500 °C/Myr. Using a relative difference in diffusion coefficients of adjacent isotopes of 4‰/amu for Fe and Ni (β = 0.25), the observations made in Toluca can be reproduced for a cooling rate of 50 °C/Myr. This value agrees with earlier cooling rate estimates based on Ni concentration profiles. This supports the idea that the fractionation measured for Fe and Ni in iron meteorites is driven by differences in diffusivities of isotopes. It also supports the validity of the value of 0.25 adopted for β for diffusion of Fe and Ni in Fe-Ni alloy in the temperature range of 400-700 °C.

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Fe isotope fractionation in iron meteorites: New insights into metal-sulphide segregation and planetary accretion

Cited by 76 publications

References 42 publications

Isotope Fractionation Processes of Selected Elements

Isotope Fractionation Processes of Selected Elements

Mass‐dependent fractionation of nickel isotopes in meteoritic metal

Diffusion‐driven kinetic isotope effect of Fe and Ni during formation of the Widmanstätten pattern

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