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.

40Ar retention in the terrestrial planets


The solid Earth is widely believed to have lost its original gases through a combination of early catastrophic release and regulated output over geologic time. In principle, the abundance of 40Ar in the atmosphere represents the time-integrated loss of gases from the interior, thought to occur through partial melting in the mantle followed by melt ascent to the surface and gas exsolution. Here we present data that reveal two major difficulties with this simple magmatic degassing scenario—argon seems to be compatible in the major phases of the terrestrial planets, and argon diffusion in these phases is slow at upper-mantle conditions. These results challenge the common belief that the upper mantle is nearly degassed of 40Ar, and they call into question the suitability of 40Ar as a monitor of planetary degassing. An alternative to magmatism is needed to release argon to the atmosphere, with one possibility being hydration of oceanic lithosphere consisting of relatively argon-rich olivine and orthopyroxene.

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

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Ar diffusive-uptake profiles in olivine and enstatite.
Figure 2: Diffusivities of Ar in olivine at T  ≈ 750 °C from experiments of differing duration.
Figure 3: Summary of diffusion data for olivine and enstatite.
Figure 4: Summary of Ar solubility measurements for olivine and enstatite compared with basaltic melt.
Figure 5: Diffusive loss of Ar from spherical pyroxene grains.
Figure 6: Transfer of Ar from olivine to melt for various equilibration scenarios.


  1. Staudacher, T. & Allègre, C. J. Terrestrial xenology. Earth Planet. Sci. Lett. 60, 389–406 (1982)

    Article  CAS  ADS  Google Scholar 

  2. Jacobsen, S. B. The Hf-W system and the origin of the Earth and Moon. Annu. Rev. Earth Planet. Sci. 33, 531–570 (2005)

    Article  CAS  ADS  Google Scholar 

  3. Halliday, A. N. & Kleine, T. in Meteorites and the Early Solar System II (eds Lauretta, D., Leshin, L. & McSween, H. Jr) 775–801 (Univ. Arizona Press, Tucson, 2006)

    Google Scholar 

  4. Boyet, M. & Carlson, R. W. 142Nd evidence for early (>4.53 Ga) global differentiation of the silicate Earth. Science 309, 576–581 (2005)

    Article  CAS  ADS  Google Scholar 

  5. Kurz, M. D., Jenkins, W. J. & Hart, S. R. Helium isotopic systematics of ocean islands and mantle heterogeneity. Nature 297, 43–46 (1982)

    Article  CAS  ADS  Google Scholar 

  6. Jochum, K. P., Hofmann, A. W., Ito, E., Seufert, H. M. & White, W. M. K, U and Th in mid-ocean ridge basalt glasses and heat production, K/U and K/Rb in the mantle. Nature 306, 431–436 (1983)

    Article  CAS  ADS  Google Scholar 

  7. Davies, G. F. Geophysically constrained mantle mass flows and the 40Ar budget: a degassed lower mantle? Earth Planet. Sci. Lett. 166, 149–162 (1999)

    Article  CAS  ADS  Google Scholar 

  8. van der Hilst, R. D., Widiyantoro, S. & Engdahl, E. R. Evidence for deep mantle circulation from global tomography. Nature 386, 578–584 (1997)

    Article  CAS  ADS  Google Scholar 

  9. Anderson, D. L. The statistics and distribution of helium in the mantle. Int. Geol. Rev. 42, 289–311 (2001)

    Article  Google Scholar 

  10. Parman, S. W., Kurz, M. D., Hart, S. R. & Grove, T. L. Helium solubility in olivine and implications for high 3He/4He in ocean island basalts. Nature 437, 1140–1143 (2005)

    Article  CAS  ADS  Google Scholar 

  11. Porcelli, D. & Turekian, K. K. The history of planetary degassing as recorded by noble gases. Treatise Geochem. 4, 281–318 (2006)

    ADS  Google Scholar 

  12. Porcelli, D. & Ballentine, C. J. in Noble Gases in Geochemistry and Cosmochemistry (eds Porcelli, D. Ballentine, C. J. & Wieler, R.) Rev. Mineral. Geochem. 47, 411–480 (2002)

    Book  Google Scholar 

  13. Klein, E. M. & Langmuir, C. H. Global correlations of ocean ridge basalt chemistry with axial depth and crustal thickness. J. Geophys. Res. 92 (B8). 8089–8115 (1987)

    Article  CAS  ADS  Google Scholar 

  14. Hellebrand, E., Snow, J. E., Dick, H. J. B. & Hofmann, A. W. Coupled major and trace elements as indicators of the extent of melting in mid-ocean-ridge peridotites. Nature 410, 677–681 (2001)

    Article  CAS  ADS  Google Scholar 

  15. Watson, E. B. & Cherniak, D. J. Lattice diffusion of Ar in quartz, with constraints on Ar solubility and evidence of nanopores. Geochim. Cosmochim. Acta 67, 2043–2062 (2003)

    Article  CAS  ADS  Google Scholar 

  16. Thomas, J. B., Cherniak, D. J. & Watson, E. B. Lattice diffusion and solubility of Ar in forsterite, enstatite, periclase, quartz and corundum. Chem. Geol. (submitted)

  17. Tsuchiyama, A. & Kawamura, K. in Noble Gas Geochemistry and Cosmochemistry (ed. Matsuda, J.) 315–323 (Terra Scientific Publishing, Tokyo, 1994)

    Google Scholar 

  18. Jambon, A., Weber, H. & Braun, O. Solubility of He, Ne, Ar, Kr and Xe in a basalt melt in the range 1250–1600°C. Geochemical implications. Geochim. Cosmochim. Acta 50, 401–408 (1986)

    Article  CAS  ADS  Google Scholar 

  19. Lux, G. The behavior of noble gases in silicate liquids: Solution, diffusion, bubbles, and surface effects, with applications to natural samples. Geochim. Cosmochim. Acta 51, 1549–1560 (1987)

    Article  CAS  ADS  Google Scholar 

  20. White, B. S., Brearley, M. & Montana, A. Solubility of argon in silicate liquids at high pressures. Am. Mineral. 74, 513–529 (1989)

    CAS  ADS  Google Scholar 

  21. Broadhurst, C. L. & Drake, M. J. Hagee, B. E. & Bernatowicz, T. J. Solubility and partitioning of Ar in anorthite, diopside, forsterite, spinel, and synthetic basalt. Geochim. Cosmochim. Acta 54, 299–309 (1990)

    Article  CAS  ADS  Google Scholar 

  22. Carroll, M. R. & Stolper, E. M. Noble gas solubility in silicate melts and glasses: New experimental results for Ar and the relationship between solubility and ionic porosity. Geochim. Cosmochim. Acta 57, 5039–5051 (1993)

    Article  CAS  ADS  Google Scholar 

  23. Shibata, T., Takahashi, E. & Matsuda, J. Solubility of neon, argon, krypton, and xenon in binary and ternary silicate systems. Geochim. Cosmochim. Acta 62, 1241–1253 (1998)

    Article  CAS  ADS  Google Scholar 

  24. Schmidt, B. C. & Keppler, H. Experimental evidence of high noble gas solubility in silicate melts under mantle pressures. Earth Planet. Sci. Lett. 195, 277–290 (2002)

    Article  CAS  ADS  Google Scholar 

  25. Batiza, R., Bernatowicz, T. J., Hohenberg, C. M. & Podosek, F. A. Relations of noble gas abundances to petrogenesis and magmatic evolution of oceanic basalts and related differentiated volcanic rocks. Contrib. Mineral. Petrol. 69, 301–313 (1979)

    Article  CAS  ADS  Google Scholar 

  26. Hiyagon, H. & Ozima, M. Noble gas distribution between basalt melt and crystals. Earth Planet. Sci. Lett. 58, 255–264 (1982)

    Article  CAS  ADS  Google Scholar 

  27. Hiyagon, H. & Ozima, M. Partition of noble-gases between olivine and basalt melt. Geochim. Cosmochim. Acta 50, 2045–2057 (1986)

    Article  CAS  ADS  Google Scholar 

  28. Brooker, R. A. et al. The “zero-charge” partitioning behaviour of noble gases during mantle melting. Nature 423, 738–741 (2003)

    Article  CAS  ADS  Google Scholar 

  29. Marty, B. & Lussiez, P. Constraints on rare gas partition coefficients from analysis of olivine-glass from a picritic mid-ocean ridge basalt. Chem. Geol. 106, 1–7 (1993)

    Article  CAS  ADS  Google Scholar 

  30. Valbracht, P. J., Honda, M., Staudigel, H., McDougall, I. & Trost, A. P. in Nobel Gas Geochemistry and Cosmochemistry (ed. Matsuda, J.) 373–381 (Terra Scientific, Tokyo, 1994)

    Google Scholar 

  31. Poreda, R. J. & Farley, K. A. Rare gases in Samoan xenoliths. Earth Planet. Sci. Lett. 113, 129–144 (1992)

    Article  CAS  ADS  Google Scholar 

  32. McDougall, I. & Green, D. H. Excess radiogenic argon in pyroxene and isotopic ages on minerals from Norwegian eclogites. Norsk Geol. Tidss 44, 183–196 (1964)

    CAS  Google Scholar 

  33. Harrison, T. M. & McDougall, I. Excess argon in metamorphic rocks from Broken Hill, New South Wales: Implications for 40Ar/39Ar age spectra and the thermal history of the region. Earth Planet. Sci. Lett. 55, 123–149 (1981)

    Article  CAS  ADS  Google Scholar 

  34. Lanphere, M. A. & Dalrymple, G. B. Identification of excess 40Ar by the 40Ar/39Ar age spectrum technique. Earth Planet. Sci. Lett. 32, 141–148 (1976)

    Article  CAS  ADS  Google Scholar 

  35. Hart, S. R. Equilibration during mantle melting: a fractal tree model. Proc. Natl Acad. Sci. USA 90, 11914–11918 (1993)

    Article  CAS  ADS  Google Scholar 

  36. Iwamori, H. A model for disequilibrium mantle melting incorporating melt transport by porous and channel flows. Nature 366, 734–737 (1993)

    Article  CAS  ADS  Google Scholar 

  37. Spiegleman, M. & Kenyon, P. The requirements for chemical disequilibrium during magma migration. Earth Planet. Sci. Lett. 109, 611–620 (1992)

    Article  ADS  Google Scholar 

  38. Cherniak, D. J. & Liang, Y. Rare earth element diffusion in natural enstatite. Geochim. Cosmochim. Acta 71, 1324–1340 (2007)

    Article  CAS  ADS  Google Scholar 

  39. Li, X.-P., Rahn, M. & Bucher, K. Serpentinites of the Zermatt-Saas ophiolite complex and their texture evolution. J. Metamorph. Geol 22, 139–177 (2004)

    Article  ADS  Google Scholar 

  40. Korenaga, J. Thermal cracking and the deep hydration of the oceanic lithosphere: A key to the generation of plate tectonics. J. Geophys. Res. 112 B05408 doi: 10.1029/2006JB004502 (2007)

    Article  ADS  Google Scholar 

  41. Rudnick, R. L. & Fountain, D. M. Nature and composition of the continental crust: a lower crustal perspective. Rev. Geophys. 33, 267–309 (1995)

    Article  ADS  Google Scholar 

  42. Allègre, C. J., Staudacher, T. & Sarda, P. Rare gas systematics: formation of the atmosphere, evolution and structure of the Earth’s mantle. Earth Planet. Sci. Lett. 81, 127–150 (1986)

    Article  ADS  Google Scholar 

  43. Lassiter, J. C. Role of recycled oceanic crust in the potassium and argon budget of the Earth: toward a resolution of the “missing argon” problem. Geochem. Geophys. Geosyst. 5 doi: 10.1029/2004GC000711 (2004)

  44. Murthy, V. R., van Westrenen, W. & Fei, Y. Experimental evidence that potassium is a substantial radioactive heat source in the planetary cores. Nature 426, 163–165 (2003)

    Article  ADS  Google Scholar 

  45. Armstrong, R. L. The persistent myth of crustal growth. Aust. J. Earth Sci. 38, 613–630 (1991)

    Article  ADS  Google Scholar 

  46. Turekian, K. K. The parameters controlling planetary degassing based on 40Ar systematics. In From Mantle to Meteorites (ed. Gopalan, K.) 147–152 (Indian Academy of Sciences, Bangalore, 1990)

    Google Scholar 

  47. McDougall, I. & Harrison, T. M. Geochronology and Thermochronology by the 40Ar/39Ar Method 1–269 (Oxford Univ. Press, New York, 1999)

    Google Scholar 

  48. Burnard, P. Diffusive fractionation of noble gases and helium isotopes during mantle melting. Earth Planet. Sci. Lett. 220, 287–295 (2004)

    Article  CAS  ADS  Google Scholar 

Download references


We are grateful to F. M. Richter and K. K. Turekian for discussions about noble gas systematics and bulk-Earth model constraints, and to M. J. Drake for comments. This research was supported by the NSF.

Author Contributions E.B.W. ran exploratory experiments, developed the melting models and wrote the manuscript; J.B.T. performed most of the experiments and interpreted the data; D.J.C. conducted the Rutherford backscattering spectroscopy analyses and reduced the raw spectra.

Author information

Authors and Affiliations


Corresponding author

Correspondence to E. Bruce Watson.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Table

This file contains Supplementary Table S1 and additional refrences. (PDF 107 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Watson, E., Thomas, J. & Cherniak, D. 40Ar retention in the terrestrial planets. Nature 449, 299–304 (2007).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


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