Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The lithospheric-to-lower-mantle carbon cycle recorded in superdeep diamonds

Abstract

The transport of carbon into Earth’s mantle is a critical pathway in Earth’s carbon cycle, affecting both the climate and the redox conditions of the surface and mantle. The largest unconstrained variables in this cycle are the depths to which carbon in sediments and altered oceanic crust can be subducted and the relative contributions of these reservoirs to the sequestration of carbon in the deep mantle1. Mineral inclusions in sublithospheric, or ‘superdeep’, diamonds (derived from depths greater than 250 kilometres) can be used to constrain these variables. Here we present oxygen isotope measurements of mineral inclusions within diamonds from Kankan, Guinea that are derived from depths extending from the lithosphere to the lower mantle (greater than 660 kilometres). These data, combined with the carbon and nitrogen isotope contents of the diamonds, indicate that carbonated igneous oceanic crust, not sediment, is the primary carbon-bearing reservoir in slabs subducted to deep-lithospheric and transition-zone depths (less than 660 kilometres). Within this depth regime, sublithospheric inclusions are distinctly enriched in 18O relative to eclogitic lithospheric inclusions derived from crustal protoliths. The increased 18O content of these sublithospheric inclusions results from their crystallization from melts of carbonate-rich subducted oceanic crust. In contrast, lower-mantle mineral inclusions and their host diamonds (deeper than 660 kilometres) have a narrow range of isotopic values that are typical of mantle that has experienced little or no crustal interaction. Because carbon is hosted in metals, rather than in diamond, in the reduced, volatile-poor lower mantle2, carbon must be mobilized and concentrated to form lower-mantle diamonds. Our data support a model in which the hydration of the uppermost lower mantle by subducted oceanic lithosphere destabilizes carbon-bearing metals to form diamond, without disturbing the ambient-mantle stable-isotope signatures. This transition from carbonate slab melting in the transition zone to slab dehydration in the lower mantle supports a lower-mantle barrier for carbon subduction.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Fig. 1: Stable-isotope compositions of diamonds and their mineral inclusions.
Fig. 2: Elemental and isotopic composition of majoritic garnet inclusions.
Fig. 3: Worldwide database of δ13C and δ15N for diamonds of lithospheric and superdeep origin.
Fig. 4: Model of diamond formation in the lithosphere, transition zone and lower mantle.

Data availability

Geochemical data that support the findings of this study are available at https://ecl.earthchem.org/view.php?id=1580Source data are provided with this paper.

References

  1. Plank, T. & Manning, C. E. Subducting carbon. Nature 574, 343–352 (2019).

    ADS  CAS  PubMed  Google Scholar 

  2. Dasgupta, R. & Hirschmann, M. M. The deep carbon cycle and melting in Earth’s interior. Earth Planet. Sci. Lett. 298, 1–13 (2010).

    ADS  CAS  Google Scholar 

  3. Creager, K. C. & Jordan, T. H. Slab penetration into the lower mantle. J. Geophys. Res. 89, 3031–3049 (1984).

    ADS  Google Scholar 

  4. Cartigny, P. Stable isotopes and the origin of diamond. Elements 1, 79–84 (2005).

    CAS  Google Scholar 

  5. Kelemen, P. B. & Manning, C. E. Reevaluating carbon fluxes in subduction zones, what goes down, mostly comes up. Proc. Natl Acad. Sci. USA 112, 3997–4006 (2015).

    ADS  Google Scholar 

  6. Sobolev, V. S. & Sobolev, N. V. New proof of very deep subsidence of eclogitized crustal rocks. Dokl. Acad. Nauk SSSR. 250, 88–90 (1982).

    ADS  Google Scholar 

  7. Duncan, M. S. & Dasgupta, R. Rise of Earth’s atmospheric oxygen controlled by efficient subduction of organic carbon. Nat. Geosci. 10, 387–392 (2017).

    ADS  CAS  Google Scholar 

  8. Li, K., Li, L., Pearson, D. G. & Stachel, T. Diamond isotope compositions indicate altered igneous oceanic crust dominates deep carbon recycling. Earth Planet. Sci. Lett. 516, 190–201 (2019).

    ADS  CAS  Google Scholar 

  9. Thomson, A. R., Walter, M. J., Kohn, S. C. & Brooker, R. A. Slab melting as a barrier to deep carbon subduction. Nature 529, 76–79 (2016).

    ADS  CAS  PubMed  Google Scholar 

  10. Walter, M. J. et al. Primary carbonatite melt from deeply subducted oceanic crust. Nature 454, 622–625 (2008).

    ADS  CAS  PubMed  Google Scholar 

  11. Kiseeva, E. S. et al. Metapyroxenite in the mantle transition zone revealed from majorite inclusions in diamonds. Geology 41, 883–886 (2013).

    ADS  CAS  Google Scholar 

  12. Ickert, R. B., Stachel, T., Stern, R. A. & Harris, J. W. Extreme 18O-enrichment in majorite constrains a crustal origin of transition zone diamonds. Geochem. Perspect. Lett. 1, 65–74 (2015).

    Google Scholar 

  13. Burnham, A. D. et al. Stable isotope evidence for crustal recycling as recorded by superdeep diamonds. Earth Planet. Sci. Lett. 432, 374–380 (2015).

    ADS  CAS  Google Scholar 

  14. Stachel, T., Brey, G. P. & Harris, J. W. Kankan diamonds (Guinea) I: from the lithosphere down to the transition zone. Contrib. Mineral. Petrol. 140, 1–15 (2000).

    ADS  CAS  Google Scholar 

  15. Stachel, T., Harris, J. W., Brey, G. P. & Joswig, W. Kankan diamonds (Guinea) II: lower mantle inclusion parageneses. Contrib. Mineral. Petrol. 140, 16–27 (2000).

    ADS  CAS  Google Scholar 

  16. Cooper, K. M., Eiler, J. M., Sims, K. W. W. & Langmuir, C. H. Distribution of recycled crust within the upper mantle: insights from the oxygen isotope composition of MORB from the Australian–Antarctic Discordance. Geochem. Geophys. Geosyst. 10, Q12004 (2009).

    ADS  Google Scholar 

  17. Cooper, K. M., Eiler, J. M., Asimow, P. D. & Langmuir, C. H. Oxygen isotope evidence for the origin of enriched mantle beneath the mid-Atlantic ridge. Earth Planet. Sci. Lett. 220, 297–316 (2004).

    ADS  CAS  Google Scholar 

  18. Eiler, J. M., Schiano, P., Kitchen, N. & Stolper, E. M. Oxygen-isotope evidence for recycled crust in the sources of mid-ocean-ridge basalts. Nature 403, 530–534 (2000).

    ADS  CAS  PubMed  Google Scholar 

  19. Regier, M. E. et al. An oxygen isotope test for the origin of Archean mantle roots. Geochem. Perspect. Lett. 9, 6–10 (2018).

    Google Scholar 

  20. Riches, A. J. V. et al. In situ oxygen-isotope, major-, and trace-element constraints on the metasomatic modification and crustal origin of a diamondiferous eclogite from Roberts Victor, Kaapvaal Craton. Geochim. Cosmochim. Acta 174, 345–359 (2016).

    ADS  CAS  Google Scholar 

  21. Grütter, H. S., Gurney, J. J., Menzies, A. H. & Winter, F. An updated classification scheme for mantle-derived garnet, for use by diamond explorers. Lithos 77, 841–857 (2004).

    ADS  Google Scholar 

  22. Ickert, R. B., Stachel, T., Stern, R. A. & Harris, J. W. Diamond from recycled crustal carbon documented by coupled δ18O–δ13C measurements of diamonds and their inclusions. Earth Planet. Sci. Lett. 364, 85–97 (2013).

    ADS  CAS  Google Scholar 

  23. Li, L., Zheng, Y. F., Cartigny, P. & Li, J. Anomalous nitrogen isotopes in ultrahigh-pressure metamorphic rocks from the Sulu orogenic belt: effect of abiotic nitrogen reduction during fluid-rock interaction. Earth Planet. Sci. Lett. 403, 67–78 (2014).

    ADS  CAS  Google Scholar 

  24. Li, L., Bebout, G. E. & Idleman, B. D. Nitrogen concentration and δ15N of altered oceanic crust obtained on ODP Legs 129 and 185: insights into alteration-related nitrogen enrichment and the nitrogen subduction budget. Geochim. Cosmochim. Acta 71, 2344–2360 (2007).

    ADS  CAS  Google Scholar 

  25. Kiseeva, E. S., Litasov, K. D., Yaxley, G. M., Ohtani, E. & Kamenetsky, V. S. Melting and phase relations of carbonated eclogite at 9–21 GPa and the petrogenesis of alkali-rich melts in the deep mantle. J. Petrol. 54, 1555–1583 (2013).

    ADS  CAS  Google Scholar 

  26. Bobrov, A. V., Litvin, Y. A., Bindi, L. & Dymshits, A. M. Phase relations and formation of sodium-rich majoritic garnet in the system Mg3Al2Si3O12–Na2MgSi5O12 at 7.0 and 8.5 GPa. Contrib. Mineral. Petrol. 156, 243–257 (2008).

    ADS  CAS  Google Scholar 

  27. Rohrbach, A. & Schmidt, M. W. Redox freezing and melting in the Earth’s deep mantle resulting from carbon–iron redox coupling. Nature 472, 209–212 (2011).

    ADS  CAS  PubMed  Google Scholar 

  28. Ringwood, A. E. Composition and Petrology of the Earth’s Mantle (McGraw-Hill, 1975).

  29. Stachel, T., Harris, J. W., Aulbach, S. & Deines, P. Kankan diamonds (Guinea) III: δ13C and nitrogen characteristics of deep diamonds. Contrib. Mineral. Petrol. 142, 465–475 (2002).

    ADS  CAS  Google Scholar 

  30. Palot, M., Pearson, D. G., Stern, R. A., Stachel, T. & Harris, J. W. Isotopic constraints on the nature and circulation of deep mantle C–H–O–N fluids: carbon and nitrogen systematics within ultra-deep diamonds from Kankan (Guinea). Geochim. Cosmochim. Acta 139, 26–46 (2014).

    ADS  CAS  Google Scholar 

  31. Cartigny, P., Palot, M., Thomassot, E. & Harris, J. W. Diamond formation: a stable isotope perspective. Annu. Rev. Earth Planet. Sci. 42, 699–732 (2014).

    ADS  CAS  Google Scholar 

  32. Katsura, T. & Ito, E. Determination of Fe–Mg partitioning between perovskite and magnesiowüstite. Geophys. Res. Lett. 23, 2005–2008 (1996).

    ADS  CAS  Google Scholar 

  33. Wood, B. J. Phase transformations and partitioning relations in peridotite under lower mantle conditions. Earth Planet. Sci. Lett. 174, 341–354 (2000).

    ADS  CAS  Google Scholar 

  34. Stachel, T. Diamonds from the asthenosphere and the transiton zone. Eur. J. Mineral. 13, 883–892 (2001).

    ADS  CAS  Google Scholar 

  35. Frost, D. J. & McCammon, C. A. The redox state of Earth’s mantle. Annu. Rev. Earth Planet. Sci. 36, 389–420 (2008).

    ADS  CAS  Google Scholar 

  36. Rohrbach, A., Ghosh, S., Schmidt, M. W., Wijbrans, C. H. & Klemme, S. The stability of Fe–Ni carbides in the Earth’s mantle: evidence for a low Fe–Ni–C melt fraction in the deep mantle. Earth Planet. Sci. Lett. 388, 211–221 (2014).

    ADS  CAS  Google Scholar 

  37. Hirschmann, M. M. & Dasgupta, R. The H/C ratios of Earth’s near-surface and deep reservoirs, and consequences for deep Earth volatile cycles. Chem. Geol. 262, 4–16 (2009).

    ADS  CAS  Google Scholar 

  38. Schmandt, B., Jacobsen, S. D., Becker, T. W., Liu, Z. & Dueker, K. G. Dehydration melting at the top of the lower mantle. Science 344, 1265–1268 (2014).

    ADS  CAS  PubMed  Google Scholar 

  39. Faccenda, M. Water in the slab: a trilogy. Tectonophysics 614, 1–30 (2014).

    ADS  Google Scholar 

  40. Zhu, F., Li, J., Liu, J., Dong, J. & Liu, Z. Metallic iron limits silicate hydration in Earth’s transition zone. Proc. Natl Acad. Sci. USA 116, 22526–22530 (2019).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  41. Marty, B. & Zimmermann, L. Volatiles (He, C, N, Ar) in mid-ocean ridge basalts: assesment of shallow-level fractionation and characterization of source composition. Geochim. Cosmochim. Acta 63, 3619–3633 (1999).

    ADS  CAS  Google Scholar 

  42. Beard, B. L. et al. Petrography and geochemistry of eclogites from the Mir kimberlite, Yakutia, Russia. Contrib. Mineral. Petrol. 125, 293–310 (1996).

    ADS  Google Scholar 

  43. Stachel, T. & Luth, R. W. Diamond formation — where, when and how? Lithos 220–203, 200–220 (2015).

    ADS  Google Scholar 

  44. Irifune, T. & Ringwood, A. E. Phase transformations in a harzburgite composition to 26 GPa: implications for dynamical behaviour of the subducting slab. Earth Planet. Sci. Lett. 86, 365–376 (1987).

    ADS  CAS  Google Scholar 

  45. Ono, S., Ito, E. & Katsura, T. Mineralogy of subducted basaltic crust (MORB) from 25 to 37 GPa, and chemical heterogeneity of the lower mantle. Earth Planet. Sci. Lett. 190, 57–63 (2001).

    ADS  CAS  Google Scholar 

  46. Ickert, R. B. & Stern, R. A. Matrix corrections and error analysis in high-precision SIMS 18O/16O measurements of Ca–Mg–Fe garnet. Geostand. Geoanal. Res. 37, 429–448 (2013).

    CAS  Google Scholar 

  47. Wang, Z., Bucholz, C., Skinner, B., Shimizu, N. & Eiler, J. Oxygen isotope constraints on the origin of high-Cr garnets from kimberlites. Earth Planet. Sci. Lett. 312, 337–347 (2011).

    ADS  CAS  Google Scholar 

  48. Mattey, D., Lowry, D. & Macpherson, C. Oxygen isotope composition of mantle peridotite. Earth Planet. Sci. Lett. 128, 231–241 (1994).

    ADS  CAS  Google Scholar 

  49. Beyer, C. & Frost, D. J. The depth of sub-lithospheric diamond formation and the redistribution of carbon in the deep mantle. Earth Planet. Sci. Lett. 461, 30–39 (2017).

    ADS  CAS  Google Scholar 

  50. McDonough, W. F. & Rudnick, R. L. Mineralogy and composition of the upper mantle. Rev. Mineral. Geochem. 37, 139–164 (1998).

    CAS  Google Scholar 

  51. Zheng, Y.-F. Calculation of oxygen isotope fractionation in anhydrous silicate minerals. Geochim. Cosmochim. Acta 57, 1079–1091 (1993); erratum 57, 3199 (1993).

    ADS  CAS  Google Scholar 

  52. Lowry, D., Mattey, D. P. & Harris, J. W. Oxygen isotope composition of syngenetic inclusions in diamond from the Finsch Mine, RSA. Geochim. Cosmochim. Acta 63, 1825–1836 (1999).

    ADS  CAS  Google Scholar 

Download references

Acknowledgements

We acknowledge Canada Excellence Research Chairs and the Deep Carbon Observatory for funding this study. We thank Diamond Trading Company (a member of the DeBeers Group of Companies) for the donation to J.W.H. of the diamonds used in this study.

Author information

Authors and Affiliations

Authors

Contributions

M.E.R. and R.A.S. collected the data. M.E.R. provided the initial data interpretation and manuscript. Input from all other authors improved the interpretation and writing. J.W.H. provided the samples.

Corresponding author

Correspondence to M. E. Regier.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks John Eiler and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Oxygen isotope values for majoritic garnet inclusions versus pressure of formation.

Majoritic garnet inclusions include those from the Juina area (Brazil), Jagersfontein (South Africa) and Kankan (Guinea) majorites. Oxygen isotope values are shown versus pressure estimates49. Error bars are 2σ (refs. 12,13).

Source data

Extended Data Fig. 2 Oxygen isotope values versus Cr/Al for Jagersfontein majoritic garnets.

A linear regression (r2 = 0.6) intersects a 5.5‰ mantle assimilate with a Cr/Al content of ~0.05, whereas primitive mantle has a Cr/Al of ~0.04 (ref. 28) and mildly depleted mantle has a Cr/Al of ~0.11 (ref. 50). Error bars are 2σ.

Source data

Extended Data Fig. 3 Ion-probe δ18O calibration for Cr-rich garnets.

The oxygen isotopic composition of coexisting garnets and olivines from peridotitic mantle xenoliths were analysed using the ion probe to determine the instrumental fractionation associated with the Cr2O3 content of garnets. The plot defines the olivine δ18O and the deviation of the measured garnet δ18O from equilibrium after Ca# matrix correction46, versus the Cr2O3 contents of the garnets. Because all the olivines have δ18O within the error of the mantle, we assume isotopic equilibrium between garnet and olivine51 and contend that the trend of SIMS-determined garnet δ18O with Cr2O3 content is a matrix effect. The trendline indicates the correction of the δ18O values to a hypothetical Cr-free garnet. Errors are 2σ.

Source data

Extended Data Fig. 4 Ion-probe δ18O calibration for enstatite Mg#.

The instrumental mass fractionation with enstatite Mg# was assessed using reference material S0170 (Mg# of 91.2; laser fluorination δ18O of +5.64‰) and S0444 (Mg# of 94.1; laser fluorination δ18O of +5.76)52. Error bars incorporate 0.10‰ analytical uncertainty in the laser fluorination measurements.

Source data

Extended Data Table 1 Mg# of bridgmanite and ferropericlase in experiments and natural inclusions in diamond
Extended Data Table 2 Standards used for electron probe microanalyser analyses

Supplementary information

Supplementary Table

Elemental and isotopic measurements of Kankan inclusions in diamond. This Excel file contains the elemental and oxygen isotope analyses of the garnet, majoritic garnet, and enstatite inclusions in Kankan diamonds that were produced in this study.

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Regier, M.E., Pearson, D.G., Stachel, T. et al. The lithospheric-to-lower-mantle carbon cycle recorded in superdeep diamonds. Nature 585, 234–238 (2020). https://doi.org/10.1038/s41586-020-2676-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-020-2676-z

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing