Enigmatic carbon isotopic variability in the oceanic upper mantle

Unraveling the origin(s) of carbon on Earth has remained challenging, not only because of the multiple isotopic fractionation episodes that may have occurred during planet formation processes but also because the end point of these processes, the current isotopic value of Earth's deep carbon reservoirs remains poorly constrained. Here, we present carbon isotopic measurements on rare undegassed mid-ocean ridge basalts from the Pacific, Atlantic, and Arctic Oceans that have preserved the isotopic signature of their mantle source. We find that Earth's present-day convecting upper mantle has variable δ<sup>13</sup>C value from ~-10 to -4‰, significantly different from the δ<sup>13</sup>C value of peridotitic diamonds and with the highest values being restricted to the Atlantic. Evidence for significant mantle heterogeneity contrasts with previous assumptions and its origin remains puzzling being uncorrelated with geochemical markers associated with either subduction and surficial recycling processes or lower mantle contributions. The data do not preclude other causes such as primordial mantle heterogeneity. We suggest that the δ<sup>13</sup>C value of the bulk silicate Earth may need to be revised.

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Publication Details

Journal
Proceedings of the National Academy of Sciences
Published
2025-06-17
DOI
https://doi.org/10.1073/pnas.2502886122
Citations
2
Primary Topic
Geological and Geochemical Analysis
Type
article
Field-Weighted Citation Impact
3.73

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article

Enigmatic carbon isotopic variability in the oceanic upper mantle

Yves Moussallam, Estelle F. Rose‐Koga, A. E. Saal, Guillaume Georgeais et al.
2 citations
Proceedings of the National Academy of Sciences
Geological and Geochemical Analysis
3.73
article

Enigmatic carbon isotopic variability in the oceanic upper mantle

Yves Moussallam, Estelle F. Rose‐Koga, A. E. Saal, Guillaume Georgeais, Kei Shimizu, Cyril Aubaud, Jean‐Luc Devidal, Kenneth T. Koga, Peter J. Michael, Pierre Cartigny
article en
2 citations

Abstract

Unraveling the origin(s) of carbon on Earth has remained challenging, not only because of the multiple isotopic fractionation episodes that may have occurred during planet formation processes but also because the end point of these processes, the current isotopic value of Earth's deep carbon reservoirs remains poorly constrained. Here, we present carbon isotopic measurements on rare undegassed mid-ocean ridge basalts from the Pacific, Atlantic, and Arctic Oceans that have preserved the isotopic signature of their mantle source. We find that Earth's present-day convecting upper mantle has variable δ<sup>13</sup>C value from ~-10 to -4‰, significantly different from the δ<sup>13</sup>C value of peridotitic diamonds and with the highest values being restricted to the Atlantic. Evidence for significant mantle heterogeneity contrasts with previous assumptions and its origin remains puzzling being uncorrelated with geochemical markers associated with either subduction and surficial recycling processes or lower mantle contributions. The data do not preclude other causes such as primordial mantle heterogeneity. We suggest that the δ<sup>13</sup>C value of the bulk silicate Earth may need to be revised.

Proceedings of the National Academy of SciencesVol. 122(25)
Centre National de la Recherche Scientifique (FR), Planetary Science Institute (US), University of Wisconsin System (US), University of Wisconsin–Madison (US), Institut de physique du globe de Paris (FR), Lamont-Doherty Earth Observatory (US), Université Clermont Auvergne (FR), Université Paris Cité (FR), Brown University (US), Observatoire de Physique du Globe de Clermont-Ferrand (FR), Laboratoire Magmas et Volcans (FR), Institut des Sciences de la Terre d'Orléans (FR), Columbia University (US), University of Tulsa (US)
National Science Foundation
Life below water
Openalex Percentile: Top 8%
Geological and Geochemical Analysis
3.73
DOIOpen Access PDFOpenAlex
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