Letter | Published:

Ancient micrometeorites suggestive of an oxygen-rich Archaean upper atmosphere

Nature volume 533, pages 235238 (12 May 2016) | Download Citation

Abstract

It is widely accepted that Earth’s early atmosphere contained less than 0.001 per cent of the present-day atmospheric oxygen (O2) level, until the Great Oxidation Event resulted in a major rise in O2 concentration about 2.4 billion years ago1. There are multiple lines of evidence for low O2 concentrations on early Earth, but all previous observations relate to the composition of the lower atmosphere2 in the Archaean era; to date no method has been developed to sample the Archaean upper atmosphere. We have extracted fossil micrometeorites from limestone sedimentary rock that had accumulated slowly 2.7 billion years ago before being preserved in Australia’s Pilbara region. We propose that these micrometeorites formed when sand-sized particles entered Earth’s atmosphere and melted at altitudes of about 75 to 90 kilometres (given an atmospheric density similar to that of today3). Here we show that the FeNi metal in the resulting cosmic spherules was oxidized while molten, and quench-crystallized to form spheres of interlocking dendritic crystals primarily of magnetite (Fe3O4), with wüstite (FeO)+metal preserved in a few particles. Our model of atmospheric micrometeorite oxidation suggests that Archaean upper-atmosphere oxygen concentrations may have been close to those of the present-day Earth, and that the ratio of oxygen to carbon monoxide was sufficiently high to prevent noticeable inhibition of oxidation by carbon monoxide. The anomalous sulfur isotope (Δ33S) signature of pyrite (FeS2) in seafloor sediments from this period, which requires an anoxic surface environment4, implies that there may have been minimal mixing between the upper and lower atmosphere during the Archaean.

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References

  1. 1.

    , & The rise of oxygen in Earth’s early ocean and atmosphere. Nature 506, 307–315 (2014)

  2. 2.

    , & in Treatise in Geochemistry Vol. 6, The Atmosphere – History (eds & ) 91–138 (2014)

  3. 3.

    , , , & Air density 2.7 billion years ago limited to less than twice modern levels by fossil raindrop imprints. Nature 484, 359–362 (2012)

  4. 4.

    & Mass-independent fractionation of sulfur isotopes in Archean sediments: strong evidence for an anoxic Archean atmosphere. Astrobiology 2, 27–41 (2002)

  5. 5.

    & Redox state of the Archean atmosphere: evidence from detrital heavy minerals in ca. 3250–2750 Ma sandstones from the Pilbara Craton, Australia. Geology 27, 115–118 (1999)

  6. 6.

    & Paleosols and the evolution of atmospheric oxygen: a critical review. Am. J. Sci. 298, 621–672 (1998)

  7. 7.

    et al. Iron formation: the sedimentary product of a complex interplay among mantle, tectonic, and biospheric processes. Econ. Geol. 105, 467–508 (2010)

  8. 8.

    The antiquity of oxygenic photosynthesis: evidence from stromatolites in sulphate-deficient Archaean lakes. Science 255, 74–77 (1992)

  9. 9.

    & Late Archean rise of aerobic microbial ecosystems. Proc. Natl Acad. Sci. USA 103, 15759–15764 (2006)

  10. 10.

    et al. Oceanic nickel depletion and a methanogen famine before the Great Oxidation Event. Nature 458, 750–753 (2009)

  11. 11.

    & Multiple sulfur isotopes and the evolution of the atmosphere. Earth Planet. Sci. Lett. 213, 1–13 (2003)

  12. 12.

    , , & in Encyclopedia of Volcanoes (ed. ) 477–494 (Academic, 2000)

  13. 13.

    & Chemistry of the Upper and Lower Atmosphere: Theory, Experiments, and Applications (Elsevier, 1999)

  14. 14.

    & Heating and thermal transformation of micrometeoroids entering the Earth's atmosphere. Icarus 89, 26–43 (1991)

  15. 15.

    & Collected extraterrestrial materials: constraints on meteor and fireball compositions. Earth Moon Planets 82–83, 325–350 (2000)

  16. 16.

    , , & The classification of micrometeorites. Meteorit. Planet. Sci. 43, 497–515 (2008)

  17. 17.

    , , & A study of Mesoproterozoic iron cosmic micro-spherules from 1.8 Ga and 1.6 Ga old strata in the Ming Tombs District, Beijing. Acta Geol. Sin. 81, 649–657 (2007)

  18. 18.

    & A giant, Late Archean lake system: the Meentheena Member (Tumbiana Formation; Fortescue Group), Western Australia. Precambr. Res. 174, 215–240 (2009)

  19. 19.

    , , & Geochronology of a Late Archaean flood basalt province in the Pilbara Craton, Australia: constraints on basin evolution, volcanic and sedimentary accumulation, and continental drift rates. Precambr. Res. 133, 143–173 (2004)

  20. 20.

    , , , & SHRIMP zircon ages constraining the depositional chronology of the Hamersley Group, Western Australia. Aust. J. Earth Sci. 51, 621–644 (2004)

  21. 21.

    et al. Refractory metal nuggets in different types of cosmic spherules. Geochim. Cosmochim. Acta 131, 247–266 (2014)

  22. 22.

    , , & Weathering of iron-rich phases in simulated Martian atmospheres. Geology 32, 1033–1036 (2004)

  23. 23.

    in Treatise in Geochemistry Vol. 6, The Atmosphere – History (eds & ) 157–175 (2014)

  24. 24.

    , & Oxidation of low carbon steel in multicomponent gases: Part I. Reaction mechanisms during isothermal oxidation. Metall. Mater. Trans A 28, 1633–1641 (1997)

  25. 25.

    & On the oxidation of iron in CO2 + CO mixtures. III: Coupled linear parabolic kinetics. Oxidat. Metals 36, 27–56 (1991)

  26. 26.

    The origins of I-type spherules and the atmospheric entry of iron micrometeoroids. Meteorit. Planet. Sci. (in the press)

  27. 27.

    , & Vertical diffusivity in the lower stratosphere from Lagrangian back-trajectory reconstructions of ozone profiles. J. Geophys. Res. 108, 4562, (2003)

  28. 28.

    et al. In situ measurements of the physical characteristics of Titan’s environment. Nature 438, 785–791 (2005)

  29. 29.

    , & The loss of mass-independent fractionation in sulfur due to a Palaeoproterozoic collapse of atmospheric methane. Geobiology 4, 271–283 (2006)

  30. 30.

    , & Evidence for a low-O2 Archean atmosphere from nickel-rich chrome spinels in 3.24 Ga impact spherules, Barberton greenstone belt, South Africa. Earth Planet. Sci. Lett. 296, 319–328 (2010)

  31. 31.

    & Self-shielding of thermal radiation by Chicxulub impact ejecta: firestorm or fizzle? Geology 37, 1135–1138 (2009)

  32. 32.

    , & Raman microspectroscopy of some iron oxides and oxyhydroxides. J. Raman Spectrosc. 28, 873–878 (1997)

  33. 33.

    , , & Kinetic isotopic fractionation during the evaporation of the iron oxide from liquid state. Proc. Lunar Planet. Sci. Conf. 25, 1459–1460 (1994)

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Acknowledgements

We thank N. Wilson and A. Langendam for assistance with electron microprobe work and electron microscopy, respectively. The authors acknowledge use of the Monash Centre for Electron Microscopy, and use of the CSIRO Microbeam Laboratory. Part of this research was undertaken on the powder diffraction beamline at the Australian Synchrotron, Victoria, Australia. M.G. acknowledges STFC grant number ST/J001260/1.

Author information

Affiliations

  1. School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria 3800, Australia

    • Andrew G. Tomkins
    • , Lara Bowlt
    • , Siobhan A. Wilson
    •  & Jeremy L. Wykes
  2. Impact and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK

    • Matthew Genge
  3. Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 2BT, UK

    • Matthew Genge
  4. Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia

    • Helen E. A. Brand
    •  & Jeremy L. Wykes
  5. Department of Earth and Planetary Sciences, Macquarie University, North Ryde, New South Wales 2113, Australia

    • Jeremy L. Wykes

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Contributions

A.G.T. conceptualized the project, conducted fieldwork and EMP analysis, and wrote the paper. L.B. conducted fieldwork, micrometeorite separation and SEM analysis. M.G. generated the micrometeorite oxidation model. S.A.W. advised on micrometeorite separation, conducted Raman spectroscopy and interpreted synchrotron results. H.E.A.B. conducted the synchrotron analysis. J.L.W. modelled the oxidizing conditions imposed at equilibrium by different atmospheres. All authors reviewed the paper prior to submission.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Andrew G. Tomkins.

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https://doi.org/10.1038/nature17678

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