The origin of the terrestrial noble-gas signature

Journal name:
Nature
Volume:
490,
Pages:
531–534
Date published:
DOI:
doi:10.1038/nature11506
Received
Accepted
Published online

In the atmospheres of Earth and Mars, xenon is strongly depleted relative to argon, when compared to the abundances in chondritic meteorites1, 2. The origin of this depletion is poorly understood3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13. Here we show that more than one weight per cent of argon may be dissolved in MgSiO3 perovskite, the most abundant phase of Earth’s lower mantle, whereas the xenon solubility in MgSiO3 perovskite is orders of magnitude lower. We therefore suggest that crystallization of perovskite from a magma ocean in the very early stages of Earth’s history concentrated argon in the lower mantle. After most of the primordial atmosphere had been lost, degassing of the lower mantle replenished argon and krypton, but not xenon, in the atmosphere. Our model implies that the depletion of xenon relative to argon indicates that perovskite crystallized from a magma ocean in the early history of Earth and perhaps also Mars.

At a glance

Figures

  1. Scanning electron microscope images of MgSiO3 perovskite samples saturated with noble gases.
    Figure 1: Scanning electron microscope images of MgSiO3 perovskite samples saturated with noble gases.

    a, Perovskite crystallized in the presence of excess xenon. The bright spots in the image are xenon-filled bubbles in perovskite below the sample surface. However, in those parts of the perovskite crystals that are far away from bubbles, no xenon can be detected, implying very low xenon solubility (<100p.p.m.). b, Argon-saturated sample with perovskite (Pv, arrows) coexisting with MgSiO3 majorite (garnet structure, Maj). Dark spots are holes previously filled by argon gas. No argon can be detected in majorite (detection limit 150p.p.m.), but the perovskite contains 3,000p.p.m. of argon. c, Another sample, containing perovskite (lighter areas) coexisting with Mg2SiO4 ringwoodite (Rw, dark) and MgSiO3 ilmenite (Ilm, dark). d, X-ray map of argon distribution in the same sample as shown in c. Argon is only found in the perovskite phase. The concentration scale shown corresponds to the range from 0 (blue) to approximately 0.8wt% (green) of Ar.

  2. A lattice-strain model of noble-gas solubility in MgSiO3 perovskite.
    Figure 2: A lattice-strain model29 of noble-gas solubility in MgSiO3 perovskite.

    The fit is based on Ar, Kr and Xe solubility data for 25GPa at 1,600°C to 1,800°C. Estimated values for the solubilities of He and Ne are also shown. Fit parameters are the effective Young’s modulus Em = 35GPa; radius of the oxygen site ri = 1.4Å, and strain-free solubility c0 = 1.53wt%. Noble-gas radii are from ref. 22. Error bars are one standard deviation. For further details, see Supplementary Information.

  3. A sample containing phase X (phX) coexisting with MgSiO3 ilmenite (Ilm), SiO2 stishovite (St) and K2CO3 carbonate.
    Figure 3: A sample containing phase X (phX) coexisting with MgSiO3 ilmenite (Ilm), SiO2 stishovite (St) and K2CO3 carbonate.

    a, Scanning electron microscope image. b, X-ray map of argon distribution; argon is only present in phase X. The concentration scale shown corresponds to the range from 0 (blue) to approximately 1wt% (red) of Ar.

References

  1. Anders, E. & Owen, T. Mars and Earth—origin and abundance of volatiles. Science 198, 453465 (1977)
  2. Pepin, R. O. & Porcelli, D. Origin of noble gases in the terrestrial planets. Rev. Mineral. Geochem. 47, 191246 (2002)
  3. Matsuda, J. & Matsubara, K. Noble gases in silica and their implication for the terrestrial missing Xe. Geophys. Res. Lett. 16, 8184 (1989)
  4. Sanloup, C. et al. Retention of xenon in quartz and Earth’s missing xenon. Science 310, 11741177 (2005)
  5. Sill, G. T. & Wilkening, L. L. Ice clathrate as a possible source of atmospheres of terrestrial planets. Icarus 33, 1322 (1978)
  6. Wacker, J. F. & Anders, E. Trapping of xenon in ice—implications for the origin of the Earth’s noble gases. Geochim. Cosmochim. Acta 48, 23732380 (1984)
  7. Jephcoat, A. P. Rare-gas solids in the Earth’s deep interior. Nature 393, 355358 (1998)
  8. Lee, K. K. M. & Steinle-Neumann, G. High-pressure alloying of iron and xenon: “missing” Xe in the Earth’s core? J. Geophys. Res. 111, B02202 (2006)
  9. Nishio-Hamane, D., Yagi, T., Sata, N., Fujita, T. & Okada, T. No reactions observed in Xe-Fe system even at Earth core pressures. Geophys. Res. Lett. 37, L04302 (2010)
  10. Pepin, R. O. On the origin and early evolution of terrestrial planet atmospheres and meteoritic volatiles. Icarus 92, 279 (1991)
  11. Dauphas, M. The dual origin of the terrestrial atmosphere. Icarus 165, 326339 (2003)
  12. Pujol, M., Marty, B. & Burgess, R. Chondritic-like xenon trapped in Archean rocks: a possible signature of the ancient atmosphere. Earth Planet. Sci. Lett. 308, 298306 (2011)
  13. Marty, B. The origins and concentrations of water, carbon, nitrogen and noble gases on Earth. Earth Planet. Sci. Lett. 313–314, 5666 (2012)
  14. Heber, V. S., Brooker, R. A., Kelley, S. P. & Wood, B. J. Crystal-melt partitioning of noble gases (helium, neon, argon, krypton, and xenon) for olivine and clinopyroxene. Geochim. Cosmochim. Acta 71, 10411061 (2007)
  15. Kojitani, H., Katsura, T. & Akaogi, M. Aluminum substitution mechanisms in perovskite-type MgSiO3: an investigation by Rietveld analysis. Phys. Chem. Mineral. 34, 257267 (2007)
  16. Lauterbach, S., McCammon, C. A., van Aken, P., Langenhorst, F. & Seifert, F. Mossbauer and ELNES spectroscopy of (Mg,Fe)(Si,Al)O3 perovskite: a highly oxidised component of the lower mantle. Contrib. Mineral. Petrol. 138, 1726 (2000)
  17. McCammon, C. A. Perovskite as a possible sink for ferric iron in the lower mantle. Nature 387, 694696 (1997)
  18. Navrotsky, A. Mantle geochemistry—a lesson from ceramics. Science 284, 17881789 (1999)
  19. Navrotsky, A. et al. Aluminum in magnesium silicate perovskite: formation, structure, and energetics of magnesium-rich defect solid solutions. J. Geophys. Res. 108, 2330 (2003)
  20. Stashans, A., Piedra, L. & Briceno, T. Fundamental and excited states of F-type centres in MgSiO3 perovskite. Physica B 405, 43504354 (2010)
  21. Stebbins, J. F. et al. Aluminum substitution in stishovite and MgSiO3 perovskite: high-resolution 27Al NMR. Am. Mineral. 91, 337343 (2006)
  22. Zhang, Y. X. & Xu, Z. J. Atomic radii of noble gas elements in condensed phases. Am. Mineral. 80, 670675 (1995)
  23. Yang, H. X., Konzett, J. & Prewitt, C. T. Crystal structure of phase X, a high pressure alkali-rich hydrous silicate and its anhydrous equivalent. Am. Mineral. 86, 14831488 (2001)
  24. Greenwood, R. C., Franchi, I. A., Jambon, A. & Buchanan, P. C. Widespread magma oceans on asteroidal bodies in the early Solar System. Nature 435, 916918 (2005)
  25. Porcelli, D., Woolum, D. & Cassen, P. Deep Earth rare gases: initial inventories, capture from the solar nebula, and losses during moon formation. Earth Planet. Sci. Lett. 193, 237251 (2001)
  26. Morbidelli, A. et al. Source regions and timescales for the delivery of water to the Earth. Meteorit. Planet. Sci. 35, 13091320 (2000)
  27. Bolfan-Casanova, N., Keppler, H. & Rubie, D. C. Water partitioning at the 660 km discontinuity and evidence for very low water solubility in magnesium silicate perovskite. Geophys. Res. Lett. 30, 1905 (2003)
  28. Pepin, R. O. Evolution of Earth’s noble gases: consequences of assuming hydrodynamic loss driven by giant impact. Icarus 126, 148156 (1997)
  29. Brooker, R. A. et al. The ‘zero charge’ partitioning behaviour of noble gases during mantle melting. Nature 423, 738741 (2003)
  30. Boettcher, S. L., Guo, Q. & Montana, A. A simple device for loading gases in high-pressure experiments. Am. Mineral. 74, 13831384 (1989)
  31. Günther, D., Frischknecht, R., Heinrich, C. A. & Kahlert, H. J. Capabilities of an Argon Fluoride 193 nm excimer laser for laser ablation inductively coupled plasma mass spectrometry microanalysis of geological materials. J. Anal. At. Spectrom. 12, 939944 (1997)
  32. Longerich, H. P., Jackson, S. E. & Gunther, D. Laser ablation inductively coupled plasma mass spectrometric transient signal data acquisition and analyte concentration calculation. J. Anal. At. Spectrom. 11, 899904 (1996)

Download references

Author information

Affiliations

  1. Bayerisches Geoinstitut, Universität Bayreuth, 95440 Bayreuth, Germany

    • Svyatoslav S. Shcheka &
    • Hans Keppler

Contributions

S.S.S. carried out all experiments and chemical analyses reported in this paper. H.K. suggested this study. Both authors wrote the manuscript together.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

Author details

Supplementary information

PDF files

  1. Supplementary Information (368K)

    This file contains Supplementary Text and Data, Supplementary Figures 1-4, Supplementary Table 1 and additional references.

Additional data