Nickel isotope fractionation during continental weathering

Spivak-Birndorf, L. J.; Wang, Shui‐Jiong; Bish, David L.; Wasylenki, Laura E.

doi:10.1016/j.chemgeo.2017.11.028

Cited by 41 publications

(38 citation statements)

References 51 publications

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“…Weathering of ultramafic lithologies drives a decrease in δ 60/58 Ni in the solid residue (Ratié et al, 2015;Spivak-Birndorf et al, 2018), which is consistent with an isotopically heavy riverine flux and seawater composition (Cameron and Vance, 2014). This process will modify whole rock δ 60/58 Ni but should not affect the composition of unaltered olivine crystals, the main host of Ni in peridotites.…”

Section: Light Ni Isotope Compositionssupporting

confidence: 58%

“…There are several important reasons behind our choice of these sample sets. As weathering of peridotites has been shown to drive fractionation of Ni isotopes (e.g., Ratié et al, 2015;Spivak-Birndorf et al, 2018), freshness of the samples was a first prerequisite.…”

Section: Peridotite Samplesmentioning

confidence: 99%

“…showing an overall consistent sense of fractionation caused by aqueous alteration. Nickel is a reasonably fluidmobile element that is isotopically fractionated during weathering in the terrestrial environment where the alteration of olivine to phyllosilicates causes a decrease in δ 60/58 Ni (Ratié et al, 2015;Spivak-Birndorf et al, 2018). Hence, alteration to a phyllosilicate-dominated mineralogy during aqueous alteration on the CI parent body can help explain the overall lower δ 60/58 Ni in CI1 chondrites Not only are the values of δ 60/58 Ni in CI1 chondrites low, but they are quite variable between different dissolution of the same meteorite (see Table 2, Steele et al, 2012 andGall et al, 2017 for independent measurements of Orgueil that span 0.16 ‰).…”

Section: Aqueous Alteration On the CI Parent Bodymentioning

confidence: 99%

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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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Section: Light Ni Isotope Compositionssupporting

confidence: 58%

Section: Peridotite Samplesmentioning

confidence: 99%

Section: Aqueous Alteration On the CI Parent Bodymentioning

confidence: 99%

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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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“…Alternatively, the anticorrelation could also be explained by the binary mixing of two sources (see text in SI) 58,59 . One endmember has a lower δ 60 Ni value and is enriched in HREE [29][30][31]42,43,[67][68][69][70] . The box showing the range for δ 60 Ni value between upper and lower quartiles.…”

Section: Discussionmentioning

confidence: 99%

“… a Boxplots showing the Ni isotopic compositions of different reservoirs 29 – 31 , 42 , 43 , 67 – 70 . The box showing the range for δ 60 Ni value between upper and lower quartiles.…”

Section: Discussionmentioning

confidence: 99%

Active methanogenesis during the melting of Marinoan snowball Earth

et al. 2021

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Geological evidence indicates that the deglaciation of Marinoan snowball Earth ice age (~635 Myr ago) was associated with intense continental weathering, recovery of primary productivity, transient marine euxinia, and potentially extensive CH4 emission. It is proposed that the deglacial CH4 emissions may have provided positive feedbacks for ice melting and global warming. However, the origin of CH4 remains unclear. Here we report Ni isotopes (δ60Ni) and Yttrium-rare earth element (YREE) compositions of syndepositional pyrites from the upper most Nantuo Formation (equivalent deposits of the Marinoan glaciation), South China. The Nantuo pyrite displays anti-correlations between Ni concentration and δ60Ni, and between Ni concentration and Sm/Yb ratio, suggesting mixing between Ni in seawater and Ni from methanogens. Our study indicates active methanogenesis during the termination of Marinoan snowball Earth. This suggests that methanogenesis was fueled by methyl sulfides produced in sulfidic seawater during the deglacial recovery of marine primary productivity.

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Isotope Fractionation Processes of Selected Elements

Hoefs¹

2021

Springer Textbooks in Earth Sciences, Geography and Environment

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Nickel isotope fractionation during continental weathering

Cited by 41 publications

References 51 publications

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

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

Active methanogenesis during the melting of Marinoan snowball Earth

Isotope Fractionation Processes of Selected Elements

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