The Isotope Geochemistry of Ni

Elliott, Tim; Steele, Robert C.

doi:10.2138/rmg.2017.82.12

Cited by 41 publications

(33 citation statements)

References 132 publications

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“…A much bigger dust input than previously imagined would have the same problem. As discussed earlier, the hydrothermal flux of Ni to the oceans is almost certainly insignificant and, given the homogeneity of the Ni isotope composition of the basalts from which they derive (Cameron et al, 2009;Elliott and Steele, 2017), it would also come with the same problem.…”

Section: Re-assessment Of the Oceanic Mass Balance Of Ni And Its Isotmentioning

confidence: 98%

Nickel and its isotopes in organic-rich sediments: implications for oceanic budgets and a potential record of ancient seawater

Ciscato

Bontognali

Vance

2018

Earth and Planetary Science Letters

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Nickel (Ni) is a biologically active element that displays a nutrient-like depth distribution in the modern oceans. Recent studies of Ni isotopes have highlighted the fact that, in common with many other transition metals, the Ni stable isotope composition, expressed as δ 60 Ni, of the dissolved phase is heavier than the inputs, at +1.3 to +1.7. The sedimentary outputs that control the high δ 60 Ni of the ocean, coupled with records for past seawater, could potentially yield new information on the past Earth system, but these are currently not well understood. Here we present the first Ni abundance and isotope data for a key output, that associated with Ni uptake into organic matter, at productive upwelling regions and elsewhere. We investigate the distribution of Ni and its isotopes in two fractions separated from the bulk sediment, an HF-digestible fraction, extracted with HF-HCl, and an organic-sulphide-rich fraction. The organic-sulphide fractions exhibit a range in δ 60 Ni, from +0.86 to +1.83. Systematic relationships between Ni concentrations, total organic carbon and Ni isotopes suggest that the organic-sulphide fraction originates in the photic zone, and is delivered to the sediment as a closed system, despite the possibility of transfer of Ni to sulphide within it. Authigenic Ni in the bulk sediment is dominated by the HF-digestible fraction which, in Ni-enriched sediments where the detrital correction is small, is very close to the modern deep ocean, at δ 60 Ni = +1.2. These data

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Section: Re-assessment Of the Oceanic Mass Balance Of Ni And Its Isotmentioning

confidence: 98%

Nickel and its isotopes in organic-rich sediments: implications for oceanic budgets and a potential record of ancient seawater

Ciscato

Bontognali

Vance

2018

Earth and Planetary Science Letters

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“…The Ni isotope composition of the BSE is more contentious than that of chondrites (Figure 8b). Earlier δ 60/58 NiBSE estimates were based on a small number of measurements of peridotitic and basaltic reference materials (Cameron et al, 2009;Steele et al, 2011;Gueguen et al, 2013;Elliott and Steele, 2017). The mantle hosts 99.97 % of Ni in the BSE and hence dominates its isotopic composition.…”

Section: The Non-chondritic Ni Isotope Compositions Of the Bsementioning

confidence: 99%

“…Previous studies lacked the precision to resolve a difference in δ 60/58 Ni between the BSE and chondrites but hinted towards and isotopically light BSE (Figure 8a). By compiling all published data and optimistically using a 2sx̄ uncertainty of the different reservoirs, Elliott and Steele (2017) suggested that the BSE has lower δ 60/58 Ni than the chondritic reservoir. Our study substantiates their speculative inference and, for the first time, documents a notable difference in δ 60/58 Ni between the BSE and Earth's building blocks (Figure 8a).…”

Section: The Non-chondritic Ni Isotope Compositions Of the Bsementioning

confidence: 99%

“…To use Ni isotopes as a tracer of core formation requires a comparison of well-constrained isotopic compositions of the BSE and chondritic meteorites. Clear deductions from published Ni data are obfuscated by much scatter but a recent compilation hints at an isotopically light BSE (Elliott and Steele, 2017). Whereas previous studies have reported relatively consistent Ni isotope compositions for chondrites and iron meteorites (Cook et al, 2007;Moynier et al, 2007;Cameron et al, 2009;Chernonozhkin et al, 2016;Gall et al, 2017), the Ni isotope composition of the BSE is more contentious (Cameron et al, 2009;Gueguen et al, 2013;Gall et al, 2017).…”

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confidence: 93%

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The non-chondritic Ni isotope composition of Earth’s mantle

Klaver

Ionov

Takazawa

et al. 2020

Geochimica et Cosmochimica Acta

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Nickel is a major element in the Earth. Due to its siderophile nature, 93 % of Ni is hosted in the core and the Ni isotope composition of the bulk silicate Earth might inform on the conditions of terrestrial core formation. Whether Earth's mantle is fractionated relative to the chondritic reservoir, and by inference to the core, is a matter of debate that largely arises from the uncertain Ni isotope composition of the mantle. We address this issue through high-precision Ni isotope measurements of fertile-to melt-depleted peridotites and compare these data to chondritic meteorites. Terrestrial peridotites that are free from metasomatic overprint display a limited range in δ 60/58 Ni (deviation of 60 Ni/ 58 Ni relative to NIST SRM 986) and no systematic variation with degree of melt depletion. The latter is consistent with olivine and orthopyroxene buffering the Ni budget and isotope composition of the refractory peridotites. As such, the average Ni isotope composition of these peridotites (δ 60/58 Ni = 0.115 ± 0.011 ‰) provides a robust estimate of the δ 60/58 Ni of the bulk silicate Earth. Peridotites with evidence for melt metasomatism range to heavier Ni isotope compositions where the introduction of clinopyroxene appears to drive an increase in δ 60/58 Ni. This requires a process where melts do not reach isotopic equilibrium with buffering olivine and orthopyroxene, but its exact nature remains obscure. Chondritic meteorites have variability in δ 60/58 Ni due to heterogeneity at the sampling scale. In particular, CI1 chondrites are displaced to isotopically lighter values due to sorption of Ni onto ferrihydrite during parent body alteration. Chondrites less extensively altered than the CI1 chondrites show no systematic differences in δ 60/58 Ni between classes and yield average δ 60/58 Ni = 0.212 ± 0.013 ‰, which is isotopically heavier than our estimate of the bulk silicate Earth. The notable isotopic difference between the bulk silicate Earth and chondrites likely results from the segregation of the terrestrial core. Our observations potentially provide a novel constraint on the conditions of terrestrial core formation but requires further experimental calibration.

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“…For example, Cl exhibits the Figure 2. The terrestrial isotopic variation vs. the relative mass difference for non-traditional stable isotopes covered in this volume (Anderson et al 2017; Barnes and Sharp 2017;Blum and Johnson 2017;Dauphas et al 2017;Elliott and Steele 2017;Kendall et al 2017;Moynier et al 2017;Nielsen et al 2017;Penniston-Dorland et al 2017;Poitrasson 2017;Qin and Wang 2017;Rouxel and Luais 2017;Stueken 2017;Teng 2017). The Dm i−j = m i − m j , where i and j represent the two isotopes that are used to report the isotopic variation, with i > j. second largest isotopic variation, which is due to kinetic isotope fractionation during volcanic degassing (Barnes and Sharp 2017).…”

Section: Introductionmentioning

confidence: 99%