I/Pu reveals Earth mainly accreted from volatile-poor differentiated planetesimals
Abstract
The observation that mid-ocean ridge basalts had ~3× higher iodine/plutonium ratios (inferred from xenon isotopes) compared to ocean island basalts holds critical insights into Earth's accretion. Understanding whether this difference stems from core formation alone or heterogeneous accretion is, however, hindered by the unknown geochemical behavior of plutonium during core formation. Here, we use first-principles molecular dynamics to quantify the metal-silicate partition coefficients of iodine and plutonium during core formation and find that both iodine and plutonium partly partition into metal liquid. Using multistage core formation modeling, we show that core formation alone is unlikely to explain the iodine/plutonium difference between mantle reservoirs. Instead, our results reveal a heterogeneous accretion history, whereby predominant accretion of volatile-poor differentiated planetesimals was followed by a secondary phase of accretion of volatile-rich undifferentiated meteorites. This implies that Earth inherited part of its volatiles, including its water, from late accretion of chondrites, with a notable carbonaceous chondrite contribution.
Additional Information
© 2023 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY). We thank T. Sun for providing the resources of making FPMD computations using Tianhe-2 supercomputers. Y.Z. is grateful for the support from Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18000000). F.L.H.T. is grateful for support from NSF grants EAR-1824002 and MGG-2054892, a Packard Fellowship, a research award from the Heritage Medical Research Institute, and start-up funds (provided by Caltech). Author contributions: Y.Z. and Q.-Z.Y. initiated the project. W.L., Y.Z., F.L.H.T., and Q.-Z.Y. designed the research. W.L. and Y.Z. performed the FPMD calculations and interpreted the data. W.L. and F.L.H.T. performed the multistage core formation modeling. W.L., G.A., Z.Y., and F.L.H.T. collected and analyzed meteoritic xenon data. W.L. and F.L.H.T. wrote the initial manuscript. All authors contributed to the discussion of the results and revision of the manuscript. The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. The raw data supporting the findings of this study have been deposited at the CaltechData: https://doi.org/10.22002/vspex-bd907.Attached Files
Published - sciadv.adg9213.pdf
Supplemental Material - sciadv.adg9213_sm.pdf
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Additional details
- PMCID
- PMC10321745
- Eprint ID
- 122117
- Resolver ID
- CaltechAUTHORS:20230705-230631366
- XDB18000000
- Chinese Academy of Sciences
- EAR-1824002
- NSF
- MGG-2054892
- NSF
- David and Lucile Packard Foundation
- Heritage Medical Research Institute
- Caltech
- Created
-
2023-07-05Created from EPrint's datestamp field
- Updated
-
2023-07-06Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences, Heritage Medical Research Institute