Global trends in novel stable isotopes in basalts: Theory and observations

Soderman, Caroline; Shorttle, Oliver; Matthews, Simon; Williams, Helen M.

doi:10.1016/j.gca.2021.12.008

Cited by 45 publications

(13 citation statements)

References 227 publications

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“…The modeled increase in δ 57 Fe flattens for T p below 1500°C (because the maximum mantle-melt isotopic fractionation is approached), whereas the data suggest a continuing increase in δ 57 Fe primary from Azuero and Quepos (60 to 70 Ma) to modern Galápagos (present day). The gradual increase in δ 57 Fe as the plume cools in this model is driven both by decreasing average melt fraction and by increasing Fe 3+ /Fe T of the melt, as the average pressure of melting decreases with decreasing T p ( 22 , 41 ). We note that our model of peridotite melting can reproduce the calculated primary MORB liquid ( 39 ) and Galápagos Spreading Center δ 57 Fe (fig.…”

Section: Resultsmentioning

confidence: 83%

“…The increase in δ 57 Fe primary from plume head to present day coincides with ∼ 400°C of plume cooling (1800° to 1400°C) ( 12 , 29 , 30 ). Smaller extents of melting from a cooler plume increase ∆ 57 Fe melt−source and create heavier Fe isotopic compositions in the melt ( 22 , 40 ). However, when we test this null hypothesis using our self-consistent mantle melting and equilibrium isotope fractionation model ( 22 , 24 ), we find that cooling of a peridotite-only lithology cannot match the observations (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Stable Fe isotopes in basalts trace mineralogical heterogeneity in their mantle source through their sensitivity to recycled crust ( 22 ). Modeling and studies of natural samples have shown that both mantle temperature and lithological heterogeneity in a mantle source could be reflected in the Fe isotope composition of its partial melts ( 18 , 22 – 24 ), where the isotope composition is reported as δ 57 Fe, per mil deviation in 57 Fe/ 54 Fe relative to the IRMM-014 standard. Because the Fe abundances of melts derived from pyroxenite and peridotite are similar, the δ 57 Fe of mantle-derived melt reflects the relative contributions of the pyroxenite and peridotite to the bulk melt ( 25 ).…”

Section: Introductionmentioning

confidence: 99%

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The evolution of the Galápagos mantle plume

et al. 2023

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The lavas associated with mantle plumes may sample domains throughout Earth’s mantle and probe its dynamics. However, plume studies are often only able to take snapshots in time, usually of the most recent plume activity, leaving the chemical and geodynamic evolution of major convective upwellings in Earth’s mantle poorly constrained. Here, we report the geodynamically key information of how the lithology and density of a plume change from plume head phase to tail. We use iron stable isotopes and thermodynamic modeling to show that the Galápagos plume has contained small, nearly constant, amounts of dense recycled crust over its 90-million-year history. Despite a temporal evolution in the amount of recycled crust-derived melt in Galápagos-related lavas, we show that this can be explained by plume cooling alone, without associated changes in the plume’s mantle source; results are also consistent with a plume rooted in a lower mantle low-velocity zone also sampling primordial components.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The evolution of the Galápagos mantle plume

et al. 2023

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“…A burgeoning literature in the mass-dependent variability of major rock forming elements in magmatic samples have the potential to provide novel constraints on source mineralogy and melting processes (e.g., Teng et al, 2017;Soderman et al, 2022), but in many cases the key parameter of isotopic fractionation, i.e. the fractionation factor between solid and melt, is insufficiently well constrained to make the most of the observations.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium olivine-melt Mg isotopic fractionation explains high δ26Mg values in arc lavas

Liu¹,

Hin²,

Coath³

et al. 2022

Geochem. Persp. Let.

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We determined equilibrium Mg isotope fractionation between olivine and melt (Δ 26/24 Mg Ol/melt ) in five, naturally quenched, olivine-glass pairs that were selected to show clear textural and chemical evidence of equilibration. We employed a high-precision, critical mixture double-spiking approach to obtain a weighted mean of Δ 26/24 Mg Ol/melt = −0.071 ± 0.010 ‰, for values corrected to a common olivineglass temperature of 1438 K. As function of temperature, the fractionation can be expressed as Δ 26/24 Mg Ol/melt = (−1.46 ± 0.26) × 10 5 /T 2 . The samples analysed have variable H 2 O content from 0.1 to ∼1.2 wt. %, yet no discernible difference in Δ 26/24 Mg Ol/melt was evident. We have used this Δ 26/24 Mg Ol/melt to revisit the puzzling issue of elevated Mg isotope ratios in arc lavas. In new Mg isotope data on sample suites from the Lesser Antilles and Mariana arcs, we show that primitive samples have MORB-like Mg isotope ratios while the evolved samples tend to have isotopically heavier compositions. The magnitude of this variability is well explained by olivine fractionation during magmatic differentiation as calculated with our new equilibrium Δ 26/24 Mg Ol/melt .

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“…Huang & Jacobsen, 2017;Kang et al, 2017;Klaver et al, 2021;Magna et al, 2015;Moynier et al, 2022;Schiller et al, 2018;Soderman et al, 2022;Valdes et al, 2014;Wu et al, 2020). Data and sources: chondrites(Amsellem et al, 2017;S.…”

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Calcium Isotope Evolution During Differentiation of Vesta and Calcium Isotopic Heterogeneities in the Inner Solar System

Zhu

Hui

Klaver

et al. 2023

Geophysical Research Letters

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We employed MC‐ICP‐MS to measure the mass‐dependent Ca isotope compositions of Vesta‐related meteorites. Eucrites and diogenites show distinct Ca isotope compositions, which is caused by crystallization of isotopically heavy orthopyroxene. The Ca isotope data support a model where the two lithologies are linked, where the diogenites, mainly composed of orthopyroxene crystallized from an eucritic melt. As normal eucrites are the main Ca reservoir on Vesta, their δ44/40Ca values (per mil 44Ca/40Ca ratios relative to NIST 915a) best represents that of bulk silicate Vesta (0.83 ± 0.04‰). This value is different from those of bulk Earth (0.94 ± 0.05‰) and Mars (1.04 ± 0.07‰), suggesting that there exists notable Ca isotope heterogeneity between inner solar system bodies. The δ44/40Ca difference between chondrules and these planets does not support the pebble accretion model as the main mechanism for planetary growth.

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Global trends in novel stable isotopes in basalts: Theory and observations

Cited by 45 publications

References 227 publications

The evolution of the Galápagos mantle plume

The evolution of the Galápagos mantle plume

Equilibrium olivine-melt Mg isotopic fractionation explains high δ26Mg values in arc lavas

Calcium Isotope Evolution During Differentiation of Vesta and Calcium Isotopic Heterogeneities in the Inner Solar System

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