HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Redox control on nitrogen isotope fractionation during planetary core formation

Abstract : The present-day nitrogen isotopic compositions of Earth's surficial (15 N-enriched) and deep reservoirs (15 N-depleted) differ significantly. This distribution can neither be explained by modern mantle degassing nor recycling via subduction zones. As the effect of planetary differentiation on the behavior of N isotopes is poorly understood, we experimentally determined N-isotopic fraction-ations during metal-silicate partitioning (analogous to planetary core formation) over a large range of oxygen fugacities (ΔIW −3.1 < logfO 2 < ΔIW −0.5, where ΔIW is the logarithmic difference between experimental oxygen fugacity [fO 2 ] conditions and that imposed by the coexistence of iron and wüstite) at 1 GPa and 1,400°C. We developed an in situ analytical method to measure the N-elemental and-isotopic compositions of experimental run products composed of Fe-C-N metal alloys and basaltic melts. Our results show substantial N-isotopic fractionations between metal alloys and silicate glasses, i.e., from −257 ± 22‰ to −49 ± 1‰ over 3 log units of fO 2. These large fractionations under reduced conditions can be explained by the large difference between N bonding in metal alloys (Fe-N) and in silicate glasses (as molecular N 2 and NH complexes). We show that the δ 15 N value of the silicate mantle could have increased by ∼20‰ during core formation due to N segregation into the core. nitrogen isotopes | fractionation | core formation | speciation | ion probe
Document type :
Journal articles
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-02172788
Contributor : Marie-Camille Caumon Connect in order to contact the contributor
Submitted on : Thursday, December 3, 2020 - 10:55:08 AM
Last modification on : Friday, March 25, 2022 - 3:00:01 PM
Long-term archiving on: : Thursday, March 4, 2021 - 6:07:27 PM

File

14485.full.pdf
Publication funded by an institution

Identifiers

Citation

Célia Dalou, Evelyn Füri, Cécile Deligny, Laurette Piani, Marie-Camille Caumon, et al.. Redox control on nitrogen isotope fractionation during planetary core formation. Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2019, 116 (29), pp.14485-14494. ⟨10.1073/pnas.1820719116⟩. ⟨hal-02172788v2⟩

Share

Metrics

Record views

124

Files downloads

48