High-precision measurements of tungsten stable isotopes and application to earth sciences

Breton, Thomas; Quitté, G.

doi:10.1039/c4ja00184b

Cited by 28 publications

(31 citation statements)

References 37 publications

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“…Differences in bulk composition (i.e., metal vs. silicate-oxide matrices) of the samples are unlikely to be the cause, as previously reported 183 W values for terrestrial, silicate-oxide dominated samples also measured by TIMS appear to be free from these effects (e.g., Mundl et al, 2018). We speculate that it could be due to different column dimensions for the two procedures, or different abundances of W in metals vs. nonmagnetic and slightly magnetic fractions, or the formation of hydrides within the plasma, as proposed by Breton and Quitté (2014). Regardless of the cause, we conclude that the negative ε 183 W values for some nonmagnetic and slightly magnetic samples measured by MC-ICP-MS are analytical artifacts, rather than natural 183 W variations, whereas the ε 183 W values for metal fractions analyzed by TIMS represent their natural 183 W isotopic composition.…”

Section: Hafnium and W Abundances 182 Hf-182 W Isotopic Compositionssupporting

confidence: 52%

Siderophile element constraints on the thermal history of the H chondrite parent body

Archer

Walker

Tino

et al. 2019

Geochimica et Cosmochimica Acta

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The abundances of highly siderophile elements (HSE: Re, Os, Ir, Ru, Pt, Pd), as well as 187 Re-187 Os and 182 Hf-182 W isotopic systematics were determined for separated metal, slightly magnetic, and nonmagnetic fractions from seven H4 to H6 ordinary chondrites. The HSE are too abundant in nonmagnetic fractions to reflect metal-silicate equilibration. The disequilibrium was likely a primary feature, as 187 Re-187 Os data indicate only minor open-system behavior of the HSE in the slightly and non-magnetic fractions. 182 Hf-182 W data for slightly magnetic and nonmagnetic fractions define precise isochrons for most meteorites that range from 5.2 ± 1.6 Ma to 15.2 ± 1.0 Ma after calcium aluminum inclusion (CAI) formation. By contrast, 182 W model ages for the metal fractions are typically 2-5 Ma older than the slope-derived isochron ages for their respective, slightly magnetic and nonmagnetic fractions, with model ages ranging from 1.4 ± 0.8 Ma to 12.6 ± 0.9 Ma after CAI formation. This indicates that the W present in the silicates and oxides was not fully equilibrated with the metal when diffusive transport among components ceased, consistent with the HSE data. Further, the W isotopic compositions of size-sorted metal fractions from some of the H chondrites also differ, indicating disequilibrium among some metal grains. The chemical/isotopic disequilibrium of siderophile elements among H chondrite components is likely the result of inefficient diffusion of siderophile elements from silicates and oxides to some metal and/or localized equilibration as H chondrites cooled towards their respective Hf-W closure temperatures. The tendency of 182 Hf-182 W isochron ages to young from H5 to H6 chondrites may indicate derivation of these meteorites from a slowly cooled, undisturbed, concentrically-zoned parent body, consistent with models that have been commonly invoked for H chondrites. Overlap of isochron ages for H4 and H5 chondrites, by contrast, appear to be more consistent with shallow impact disruption models.

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Section: Hafnium and W Abundances 182 Hf-182 W Isotopic Compositionssupporting

confidence: 52%

Siderophile element constraints on the thermal history of the H chondrite parent body

Archer

Walker

Tino

et al. 2019

Geochimica et Cosmochimica Acta

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“…1,2 In this context, isotopic analysis of Ni shows great potential for geo-and planetary applications. Other transition metals that have recently been studied in this context include Fe 3 , Cr 4 , Mo 5 , Zn 6 and W 7 . Ni, mostly partitioned into the metal-silicatetroilite system, experiences mass-dependent fractionation of its Notes and references a Ghent University, Department of Analytical Chemistry, Krijgslaan 281 -S12, 9000 Ghent, Belgium.…”

Section: Introductionmentioning

confidence: 99%

Development of an isolation procedure and MC-ICP-MS measurement protocol for the study of stable isotope ratio variations of nickel

Chernonozhkin

Goderis

Lobo

et al. 2015

J. Anal. At. Spectrom.

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Variations in the isotopic composition of Ni resulting from natural mass-dependent processes in terrestrial or extraterrestrial conditions, inhomogeneous distribution of nucleosynthetic components and/or ingrowth from radioactive parent nuclides, help us to further understand the early formation history of Solar System materials and the nature of the processes these materials subsequently experienced. In studies of Ni isotope systematics, mass-dependent variations in the isotopic composition of Ni are often bypassed because of the challenges associated with the sample preparation. At the level of natural variation studied, Ni isotope ratio measurements are extremely sensitive to spectral interference, artificial on-column isotope fractionation and possibly even to the mass bias correction model applied. To adequately address these complications, an isolation procedure and measurement protocol relying on multi-collector ICP-mass spectrometry (MC-ICP-MS) have been designed and validated in this work. The overall reproducibility obtained based on repeated measurement of a Sigma-Aldrich high-purity Ni standard is 0.036&, 0.049 parts per thousand, 0.078 parts per thousand and 0.53 parts per thousand for delta Ni-60/58, delta Ni-61/58, delta Ni-62/58 and delta Ni-64/58, respectively (n = 14; 2 SD). Nickel isotope ratio variations have been studied in a set of iron meteorites and geological reference materials, and the results obtained, except for those suffering from an elevated Zn-64 background, show good agreement with the available literature data. By using the flexible generalized power law with a variable discrimination exponent and the three-isotope method, the processes underlying natural mass fractionation of Ni for terrestrial reference materials were found to have a mixed equilibrium/kinetic nature. Mass-dependent Ni fractionation was observed between sample fractions of the Canyon Diablo iron meteorite, and the extracted fractionation factor beta corresponds to isotope partitioning following the power law

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“…This step removes trace amounts of Ca and Cr from the sample, based on the Ti purification procedure described by Zhang et al . () and the W separation procedure described by Breton and Quitté (). The AG1‐X8 anion exchange resin, packed in the small‐sized polypropylene column, was washed by passing 9 ml of 3 mol l −1 HNO 3 , 3 ml of H 2 O, 5 ml of 0.4 mol l −1 HCl + 1 mol l −1 HF, 5 ml of concentrated 9 mol l −1 HCl + 0.01 mol l −1 HF and 9 ml of H 2 O.…”

Section: Methodsmentioning

confidence: 99%

Sequential Chemical Separation of Cr and Ti from a Single Digest for High‐Precision Isotope Measurements of Planetary Materials

Hibiya

Iizuka

Yamashita

et al. 2018

Geostandard Geoanalytic Res

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Combined determination of Cr and Ti isotopes of planetary materials offers a means with which to investigate their genetic relationship and the evolution of the protoplanetary disk. Here, we report the new sequential chemical separation procedure for combined Cr and Ti isotope ratio measurements. It comprises three steps: (a) Fe removal using AG1-X8 anion exchange resin, (b) Ti separation using TODGA resin and (c) Cr separation using AG50W-X8 cation exchange resin (with one additional step of Ti purification using AG1-X8 anion exchange resin for samples having high Cr/Ti and Ca/Ti ratios). We applied the proposed procedure to terrestrial and meteorite samples with various compositions. Typical recovery rates of 90-100% were achieved with total procedural Cr and Ti blanks of 3-5 and 2-3 ng, respectively. We measured the Cr and Ti isotope compositions of the separated samples using thermal ionisation mass spectrometry and multiple collector-inductively coupled plasma-mass spectrometry, respectively. Our Cr and Ti isotope data were found to be consistent with those of previous studies of individual Cr and Ti isotopic compositions of the meteorites. These results demonstrate the capability of our separation method when applied to combined high-precision Cr and Ti isotope analyses for single digests of planetary materials.

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High-precision measurements of tungsten stable isotopes and application to earth sciences

Abstract: A new method for high precision measurements of W stable isotopes by MC-ICPMS enables to discriminate small mass-dependent fractionations, with applications in numerous fields of earth, planetary and environmental sciences.

Cited by 28 publications

References 37 publications

Siderophile element constraints on the thermal history of the H chondrite parent body

Siderophile element constraints on the thermal history of the H chondrite parent body

Development of an isolation procedure and MC-ICP-MS measurement protocol for the study of stable isotope ratio variations of nickel

Sequential Chemical Separation of Cr and Ti from a Single Digest for High‐Precision Isotope Measurements of Planetary Materials

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