Skip to main content

Thank you for visiting 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 oxidation state of the mantle and the extraction of carbon from Earth’s interior


Determining the oxygen fugacity of Earth’s silicate mantle is of prime importance because it affects the speciation and mobility of volatile elements in the interior and has controlled the character of degassing species from the Earth since the planet’s formation1. Oxygen fugacities recorded by garnet-bearing peridotite xenoliths from Archaean lithosphere are of particular interest, because they provide constraints on the nature of volatile-bearing metasomatic fluids and melts active in the oldest mantle samples, including those in which diamonds are found2,3. Here we report the results of experiments to test garnet oxythermobarometry equilibria4,5 under high-pressure conditions relevant to the deepest mantle xenoliths. We present a formulation for the most successful equilibrium and use it to determine an accurate picture of the oxygen fugacity through cratonic lithosphere. The oxygen fugacity of the deepest rocks is found to be at least one order of magnitude more oxidized than previously estimated. At depths where diamonds can form, the oxygen fugacity is not compatible with the stability of either carbonate- or methane-rich liquid but is instead compatible with a metasomatic liquid poor in carbonate and dominated by either water or silicate melt. The equilibrium also indicates that the relative oxygen fugacity of garnet-bearing rocks will increase with decreasing depth during adiabatic decompression. This implies that carbon in the asthenospheric mantle will be hosted as graphite or diamond but will be oxidized to produce carbonate melt through the reduction of Fe3+ in silicate minerals during upwelling. The depth of carbonate melt formation will depend on the ratio of Fe3+ to total iron in the bulk rock. This ‘redox melting’ relationship has important implications for the onset of geophysically detectable incipient melting and for the extraction of carbon dioxide from the mantle through decompressive melting.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Comparison between oxythermobarometers.
Figure 2: Log( f O 2 ) (normalized to the FMQ buffer) calculated for xenoliths from the cratonic lithosphere using equilibrium (3).
Figure 3: Speciation of carbon in adiabatically upwelling mantle.


  1. Kasting, J. F., Eggler, D. H. & Raeburn, S. P. Mantle redox evolution and the oxidation state of the Archean atmosphere. J. Geol. 101, 245–257 (1993)

    ADS  CAS  Article  Google Scholar 

  2. Luth, R. W., Virgo, D., Boyd, F. R. & Wood, B. J. Ferric iron in mantle-derived garnets. Contrib. Mineral. Petrol. 104, 56–72 (1990)

    ADS  CAS  Article  Google Scholar 

  3. Woodland, A. B. & Koch, M. Variation in oxygen fugacity with depth in the upper mantle beneath Kaapvaal craton, South Africa. Earth Planet. Sci. Lett. 214, 295–310 (2003)

    ADS  CAS  Article  Google Scholar 

  4. O’Neill, H. St C. & Wall, V. J. The olivine-orthopyroxene-spinel oxygen geobarometer, the nickel precipitation curve, and the oxygen fugacity of the Earth’s upper mantle. J. Petrol. 28, 1169–1191 (1987)

    ADS  Article  Google Scholar 

  5. Wood, B. J. Oxygen barometry of spinel peridotites. Rev. Mineral. Geochem. 25, 417–432 (1991)

    CAS  Google Scholar 

  6. Ballhaus, C. & Frost, B. R. The generation of oxidized CO2-bearing basaltic melts from reduced CH4-bearing upper mantle sources. Geochem. Cosmochem. Acta 58, 4931–4940 (1994)

    ADS  CAS  Article  Google Scholar 

  7. Gudmundsson, G. & Wood, B. J. Experimental tests of garnet peridotite oxygen barometry. Contrib. Mineral. Petrol. 119, 56–67 (1995)

    ADS  CAS  Article  Google Scholar 

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

    ADS  CAS  Article  Google Scholar 

  9. Ballhaus, C. Is the upper mantle metal-saturated? Earth Planet. Sci. Lett. 132, 75–86 (1995)

    ADS  CAS  Article  Google Scholar 

  10. O’Neill St C, H., Rubie, D. C., Canil, D., Geiger, C. A. & Ross, C. R. in Evolution of the Earth and Planets (eds Takahashi, E., Jeanloz, R. & Rubie, D. C.) 74–88 (Geophys. Monogr. 74, American Geophysical Union, 1993)

    Google Scholar 

  11. Woodland, A. B. & O’Neill, H. St C. Thermodynamic data for Fe-bearing phases obtained using noble metal alloys as redox sensors. Geochim. Cosmochim. Acta 61, 4359–4366 (1997)

    ADS  CAS  Article  Google Scholar 

  12. Woodland, A. B. & O’Neill, H. St C. Synthesis and stability of Fe3Fe2 3+Si3O12 garnet and phase relations with Fe3Al2Si3O12-Fe3Fe2 3+Si3O12 solutions. Am. Mineral. 78, 1000–1013 (1993)

    Google Scholar 

  13. Holland, T. & Powell, R. An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids. J. Metamorph. Geol. 29, 333–383 (2011)

    ADS  CAS  Article  Google Scholar 

  14. Canil, D. & O’Neill, H. St C. Distribution of ferric iron in some upper-mantle assemblages. J. Petrol. 37, 609–635 (1996)

    ADS  CAS  Article  Google Scholar 

  15. McCammon, C. A. & Kopylova, M. G. A redox profile of the Slave mantle and oxygen fugacity control in the cratonic mantle. Contrib. Mineral. Petrol. 148, 55–68 (2004)

    ADS  CAS  Article  Google Scholar 

  16. Lazarov, M., Woodland, A. B. & Brey, G. P. Thermal state and redox conditions of the Kaapvaal mantle: a study of xenoliths from the Finsch mine, South Africa. Lithos 112S, 913–923 (2009)

    ADS  CAS  Article  Google Scholar 

  17. Creighton, S. et al. Oxidation of the Kaapvaal lithospheric mantle driven by metasomatism. Contrib. Mineral. Petrol. 157, 491–504 (2009)

    ADS  CAS  Article  Google Scholar 

  18. Creighton, S., Stachel, T., Eichenberg, D. & Luth, R. W. Oxidation state of the lithospheric mantle beneath Diavik diamond mine, central Slave craton, NWT, Canada. Contrib. Mineral. Petrol. 159, 645–657 (2010)

    ADS  CAS  Article  Google Scholar 

  19. Yaxley, G. M., Berry, A. J., Kamenetsky, V. S., Woodland, A. B. & Golovin, A. V. An oxygen fugacity profile through the Siberian Craton-Fe K-edge XANES determinations of Fe3+/ΣFe in garnets in peridotite xenoliths from the Udachnaya East kimberlite. Lithos 140–141, 142–151 (2012)

    ADS  Article  Google Scholar 

  20. Eggler, D. H. & Baker, D. R. in High-Pressure Research in Geophysics (eds Akimoto, S. & Manghnani, M. H.) 237–250 (Springer, 1982)

    Book  Google Scholar 

  21. 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  Article  Google Scholar 

  22. Stagno, V. & Frost, D. J. Carbon speciation in the asthenosphere: experimental measurements of the redox conditions at which carbonate-bearing melts coexist with graphite or diamond in peridotite assemblages. Earth Planet. Sci. Lett. 300, 72–84 (2010)

    ADS  CAS  Article  Google Scholar 

  23. Peslier, A. H., Woodland, A. B., Bell, D. R. & Lazarov, M. Olivine water contents in the continental lithosphere and the longevity of cratons. Nature 467, 78–81 (2010)

    ADS  CAS  Article  Google Scholar 

  24. McDonough, W. F. & Sun, S.-s. The composition of the Earth. Chem. Geol. 120, 223–253 (1995)

    ADS  CAS  Article  Google Scholar 

  25. Bézos, A. & Humler, E. The Fe3+/ΣFe ratios of MORB glasses and their implications for mantle melting. Geochim. Cosmochim. Acta 69, 711–725 (2005)

    ADS  Article  Google Scholar 

  26. Blundy, J. D., Brodholt, J. P. & Wood, B. J. Carbon-fluid equilibria and the oxidation state of the upper mantle. Nature 349, 321–324 (1991)

    ADS  CAS  Article  Google Scholar 

  27. Saal, A. E., Hauri, E., Langmuir, C. H. & Perfit, M. R. Vapour undersaturation in primitive mid-ocean-ridge basalts and the volatile content of Earth’s upper mantle. Nature 419, 451–455 (2002)

    ADS  CAS  Article  Google Scholar 

  28. Gaillard, F., Malki, M., Iacono-Marziano, G., Pichavant, M. & Scaillet, B. Carbonatite melts and electrical conductivity in the asthenosphere. Science 322, 1363–1365 (2008)

    ADS  CAS  Article  Google Scholar 

  29. Gu, Y. J., Lerner-Lam, A. L., Dziewonski, A. M. & Ekstrom, G. Deep structure and seismic anisotropy beneath the East Pacific Rise. Earth Planet. Sci. Lett. 232, 259–272 (2005)

    ADS  CAS  Article  Google Scholar 

  30. Rohrbach, A. et al. Metal saturation in the upper mantle. Nature 449, 456–458 (2007)

    ADS  CAS  Article  Google Scholar 

  31. 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  Article  Google Scholar 

  32. McKenzie, D. The extraction of magma from the crust and mantle. Earth Planet. Sci. Lett. 74, 81–91 (1985)

    ADS  CAS  Article  Google Scholar 

  33. Campbell, I. H. Large igneous provinces and the plume hypothesis. Elements 1, 265–269 (2005)

    Article  Google Scholar 

  34. O’Neill, H. St C. & Wood, B. J. An experimental study of Fe-Mg partitioning between garnet and olivine and its calibration as a geothermometer. Contrib. Mineral. Petrol. 70, 59–70 (1979)

    ADS  Article  Google Scholar 

  35. Balta, J. B., Asimow, P. D. & Mosenfelder, J. L. Hydrous, low-carbon melting of garnet peridotite. J. Petrol. 52, 2079–2105 (2011)

    ADS  CAS  Article  Google Scholar 

  36. McCammon, C. A. A Mössbauer milliprobe: practical considerations. Hyperfine Interact. 92, 1235–1239 (1994)

    ADS  CAS  Article  Google Scholar 

  37. Prescher, C., McCammon, C. & Dubrovinsky, L. MossA: a program for analyzing energy-domain Mossbauer spectra from conventional and synchrotron sources. J. Appl. Crystallogr. 45, 329–331 (2012)

    CAS  Article  Google Scholar 

  38. Amthauer, G., Annersten, H. & Hafner, S. S. The Mössbauer spectrum of 57Fe in silicate garnets. Z. Kristallogr. 143, 14–55 (1976)

    CAS  Google Scholar 

  39. Schwerdtfeger, K. & Zwell, L. Activities in solid iridium-iron and rhodium-iron alloys at 1200°C. Trans. Metall. Soc. AIME 242, 631–633 (1968)

    CAS  Google Scholar 

  40. Swartzendruber, L. J. The Fe-Ir (iron-iridium) system. Bull. Alloy Phase Diagr. 5, 48–52 (1984)

    CAS  Article  Google Scholar 

  41. Wiser, N. & Wood, B. J. Experimental determination of activities in Fe-Mg olivine at 1400K. Contrib. Mineral. Petrol. 108, 146–153 (1991)

    ADS  CAS  Article  Google Scholar 

  42. Ganguly, J., Cheng, C. & Tirone, M. Thermodynamics of aluminosilicate garnet solid solutions: new experimental data, an optimized model, and thermometric applications. Contrib. Mineral. Petrol. 126, 137–151 (1996)

    ADS  CAS  Article  Google Scholar 

  43. Wood, B. J. & Nicholls, J. The thermodynamical properties of reciprocal solid solutions. Contrib. Mineral. Petrol. 66, 389–400 (1978)

    ADS  CAS  Article  Google Scholar 

Download references


Financial support was provided to V.S. by the European Commission under the Marie Curie Action for Early Stage Training of Researchers within the 6th Framework Programme (contract number MEST-CT-2005-019700) and by the German Science Foundation (grant FR1555/5-1).

Author information

Authors and Affiliations



V.S. and D.J.F. wrote the paper. V.S. performed most of the experiments, analytical measurements and calculations. D.O.O. performed high-pressure experiments. C.A.M. collected and interpreted Mössbauer data. D.J.F. developed the thermodynamic model.

Corresponding author

Correspondence to Daniel J. Frost.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text and Data and Supplementary Figures 1-2. (PDF 439 kb)

Supplementary Tables

This file contains Supplementary Tables 1-5. (XLS 38 kb)

Supplementary Data

This file contains the thermodynamic model developed in this study and also the calculation for the fo2 of a garnet peridotite assemblage. (XLS 95 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Stagno, V., Ojwang, D., McCammon, C. et al. The oxidation state of the mantle and the extraction of carbon from Earth’s interior. Nature 493, 84–88 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


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.


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