Sulfur-controlled iron isotope fractionation experiments of core formation in planetary bodies

Shahar, Anat; Hillgren, V. J.; Horan, M. F.; Mesa-García, J.; Kaufman, Larry; Mock, T. D.

doi:10.1016/j.gca.2014.08.011

Cited by 53 publications

(40 citation statements)

References 50 publications

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“…This is not observed in experimental studies and in natural samples for which metal-silicate equilibrium was assessed (Roskosz et al, 2006;Poitrasson et al, 2009;Hin et al, 2012;Jordan and Young, 2014;Shahar et al, 2015).…”

Section: Comparison With Existing Datamentioning

confidence: 93%

Spinel–olivine–pyroxene equilibrium iron isotopic fractionation and applications to natural peridotites

Roskosz

Sio

Dauphas

et al. 2015

Geochimica et Cosmochimica Acta

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Eight spinel-group minerals were synthesized by a flux-growth method producing spinels with varying composition and Fe 3+ /Fetot ratios. The mean force constants of iron bonds in these minerals were determined by synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS) in order to determine the reduced isotopic partition function ratios (β β β β-factors) of these spinels. The mean force constants are strongly dependent on the Fe 3+ /Fetot of the spinel but are independent, or weakly dependent on other structural and compositional parameters. From our spectroscopic data, it is found that a single redoxdependent calibration line accounts for the effects of Fe 3+ /Fetot on the β β β β-factors of spinels. This calibration successfully describes the equilibrium Fe isotopes fractionation factors between spinels and silicates (olivine and pyroxenes). Our predictions are in excellent agreement with independent determinations for the equilibrium Fe isotopic fractionations for the magnetite-fayalite and the magnetite-hedenbergite couples. Our calibration applies to the entire range of Fe 3+ /Fetot ratios found in natural spinels and provides a basis for interpreting iron isotopic variations documented in mantle peridotites. Except for a few exceptions, most of the samples measured so far are in isotopic disequilibrium, reflecting metasomatism and partial melting processes.

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Section: Comparison With Existing Datamentioning

confidence: 93%

Spinel–olivine–pyroxene equilibrium iron isotopic fractionation and applications to natural peridotites

Roskosz

Sio

Dauphas

et al. 2015

Geochimica et Cosmochimica Acta

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“…), although recent estimates based on Fe isotopes places an upper limit of ~8 wt% S in the core (Shahar et al. ). The unknown S abundance, or other potential light elements in the core, has an important influence on the density and inferred radius of the Martian core (Mocquet et al.…”

Section: Current State Of Knowledge Related To Specific Volatilesmentioning

confidence: 97%

A review of volatiles in the Martian interior

Filiberto

Baratoux

Beaty

et al. 2016

Meteorit & Planetary Scien

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23Multiple observations from missions to Mars have revealed compelling evidence for a 24 volatile-rich Martian crust. A leading theory contends that eruption of basaltic magmas was the 25 ultimate mechanism of transfer of volatiles from the mantle toward the surface after an initial 26 outgassing related to the crystallization of a magma ocean. However, the concentrations of 27 volatile species in ascending magmas and in their mantle source regions are highly uncertain.

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“…More importantly, fractionation of Fe isotopes between S-rich metallic melts and silicates becomes much less detectable with increasing temperature, and is usually supposed negligible considering our present level of precision, above 1250 • C as determined through experimental studies (Poitrasson et al, 2009;Hin et al, 2012). [Notice that this view has been recently challenged by Shahar et al (2015) whose results indicate significant fractionations between metallic melts and melted silicates at 1600 • C. However, the magnitude and direction of these isotopic fractionations are not consistent with the available analyses on magmatic irons (bulk samples) and the results presented here. A discussion of these results and previous ones is beyond the scope of this paper.…”

Section: Origin Of the High δ 56 Fe Values In Ureilitesmentioning

confidence: 99%

Early stages of core segregation recorded by Fe isotopes in an asteroidal mantle

Barrat

Rouxel

Wang

et al. 2015

Earth and Planetary Science Letters

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Available online xxxx Editor: B. Marty Keywords: iron isotopes achondrite ureilite coreUreilite meteorites are achondrites that are debris of the mantle of a now disrupted differentiated asteroid rich in carbon. They provide a unique opportunity to study the differentiation processes of such a body. We analyzed the iron isotopic compositions of 30 samples from the Ureilite Parent Body (UPB) including 29 unbrecciated ureilites and one ureilitic trachyandesite (ALM-A) which is at present the sole large crustal sample of the UPB. The δ 56 Fe of the whole rocks fall within a restricted range, from 0.01 to 0.11h, with an average of +0.056 ± 0.008h, which is significantly higher than that of chondrites.We show that this difference can be ascribed to the segregation of S-rich metallic melts at low degrees of melting at a temperature close to the Fe-FeS eutectic, and certainly before the onset of the melting of the silicates (<1100 • C), in agreement with the marked S depletions, and the siderophile element abundances of the ureilites. These results point to an efficient segregation of S-rich metallic melts during the differentiation of small terrestrial bodies.

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Sulfur-controlled iron isotope fractionation experiments of core formation in planetary bodies

Cited by 53 publications

References 50 publications

Spinel–olivine–pyroxene equilibrium iron isotopic fractionation and applications to natural peridotites

Spinel–olivine–pyroxene equilibrium iron isotopic fractionation and applications to natural peridotites

A review of volatiles in the Martian interior

Early stages of core segregation recorded by Fe isotopes in an asteroidal mantle

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