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Geomagnetic field strength 3.2 billion years ago recorded by single silicate crystals

Nature volume 446, pages 657–660 (2007)Cite this article

Abstract

The strength of the Earth’s early geomagnetic field is of importance for understanding the evolution of the Earth’s deep interior, surface environment and atmosphere. Palaeomagnetic and palaeointensity data from rocks formed near the boundary of the Proterozoic and Archaean eons, some 2.5 Gyr ago, show many hallmarks of the more recent geomagnetic field. Reversals are recorded1, palaeosecular variation data2 indicate a dipole-dominated morphology and available palaeointensity values are similar to those from younger rocks1,2,3. The picture before 2.8 Gyr ago is much less clear. Rocks of the Archaean Kaapvaal craton (South Africa) are among the best-preserved, but even they have experienced low-grade metamorphism4. The variable acquisition of later magnetizations by these rocks is therefore expected, precluding use of conventional palaeointensity methods. Silicate crystals from igneous rocks, however, can contain minute magnetic inclusions capable of preserving Archaean-age magnetizations. Here we use a CO2 laser heating approach and direct-current SQUID magnetometer measurements to obtain palaeodirections and intensities from single silicate crystals that host magnetite inclusions. We find 3.2-Gyr-old field strengths that are within 50 per cent of the present-day value, indicating that a viable magnetosphere sheltered the early Earth’s atmosphere from solar wind erosion.

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Figure 1: Examples of natural remanent magnetization versus thermoremanent magnetization data from Thellier experiments on Archaean oriented single silicate crystals using a CO 2 laser/SQUID system.
Figure 2: Stereonets showing palaeomagnetic and palaeointensity results from the Kaapvaal craton, South Africa.

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References

  1. Dunlop, D. J. & Yu, Y. in Timescales of the Paleomagnetic Field (eds Channell, J. E. T., Kent, D. V., Lowrie, W. & Meert, J. G) 85–100 (Geophys. Monograph Ser. 145, American Geophysical Union, Washington DC, 2004)

    Google Scholar 

  2. Smirnov, A. V. & Tarduno, J. A. Secular variation of the Late Archean–Early Proterozoic geodynamo. Geophys. Res. Lett. 31, L16607 (2004)

    Article  ADS  Google Scholar 

  3. Smirnov, A. V., Tarduno, J. A. & Pisakin, B. N. Paleointensity of the Early Geodynamo (2.45 Ga) as recorded in Karelia: a single crystal approach. Geology 31, 415–418 (2003)

    Article  ADS  Google Scholar 

  4. Tice, M. M., Bostick, B. C. & Lowe, D. R. Thermal history of the 3.5–3.2 Ga Onverwacht and Fig Tree Groups, Barberton greenstone belt, South Africa, inferred by Raman microspectroscopy of carbonaceous material. Geology 32, 37–40 (2004)

    Article  ADS  CAS  Google Scholar 

  5. Néel, L. Some theoretical aspects of rock magnetism. Adv. Phys. 4, 191–243 (1955)

    Article  ADS  Google Scholar 

  6. Dunlop, D. J. & Özdemir, Ö. Rock Magnetism, Fundamentals and Frontiers (Cambridge Univ. Press, Cambridge, UK, 1997)

    Book  Google Scholar 

  7. Pullaiah, G., Irving, E., Buchan, K. L. & Dunlop, D. J. Magnetization changes caused by burial and uplift. Earth Planet. Sci. Lett. 28, 133–143 (1975)

    Article  ADS  Google Scholar 

  8. Hale, C. J. The intensity of the geomagnetic field at 3.5 Ga: Paleointensity results from the Komati Formation, Barberton Mountain Land, South Africa. Earth Planet. Sci. Lett. 86, 354–364 (1987)

    Article  ADS  Google Scholar 

  9. Yoshihara, A. & Hamano, Y. Paleomagnetic constraints on the Archean geomagnetic field intensity obtained from komatiites of the Barberton and Belingwe greenstone belts, South Africa and Zimbabwe. Precambr. Res. 131, 111–142 (2004)

    Article  ADS  CAS  Google Scholar 

  10. McElhinny, M. W. & Senanayake, W. E. Paleomagnetic evidence for the existence of the geomagnetic field at 3.5 Ga Ago. J. Geophys. Res. 85, 3523–3528 (1980)

    Article  ADS  Google Scholar 

  11. Cottrell, R. D. & Tarduno, J. A. Geomagnetic paleointensity derived from single plagioclase crystals. Earth Planet. Sci. Lett. 169, 1–5 (1999)

    Article  ADS  CAS  Google Scholar 

  12. Cottrell, R. D. & Tarduno, J. A. In search of high fidelity geomagnetic paleointensities: A comparison of single crystal and whole rock Thellier-Thellier analyses. J. Geophys. Res. 105, 23,579–23,594 (2000)

    Article  ADS  Google Scholar 

  13. Tarduno, J. A., Cottrell, R. D. & Smirnov, A. V. The paleomagnetism of single silicate crystals: Recording geomagnetic field strength during mixed polarity intervals, superchrons and inner core growth. Rev. Geophys. 44 RG1002 doi: 10.1029/2005RG000189 (2006)

    Article  ADS  Google Scholar 

  14. Poujol, M., Robb, L. J., Anhaeusser, C. R. & Gericke, B. A review of the geochronological constraints on the evolution of the Kaapvaal Craton, South Africa. Precambr. Res. 127, 181–213 (2003)

    Article  ADS  CAS  Google Scholar 

  15. Geissman, J. W., Harlan, S. S. & Brearley, A. J. The physical isolation and identification of carriers of geologically stable remanent magnetization: Paleomagnetic and rock magnetic microanalysis and electron microscopy. Geophys. Res. Lett. 15, 479–482 (1988)

    Article  ADS  Google Scholar 

  16. Renne, P. R. & Onstott, T. C. Laser-selective demagnetization: A new technique in paleomagnetism and rock magnetism. Science 242, 1152–1155 (1988)

    Article  ADS  CAS  Google Scholar 

  17. Gose, W. A., Hanson, R. E., Dalziel, I. W. D., Pancake, J. A. & Seidel, E. K. Paleomagnetism of the 1.1 Ga Umkondo large igneous province in southern Africa. J. Geophys. Res. 111, B09101 (2006)

    Article  ADS  Google Scholar 

  18. Layer, P. W., Lopez-Martinez, M., Kroner, A., York, D. & McWilliams, M. Thermochronometry and palaeomagnetism of Archaean Nelshoogte Pluton, South Africa. Geophys. J. Int. 135, 129–145 (1998)

    Article  ADS  Google Scholar 

  19. Hargraves, R. B., Rehacek, J. & Hooper, P. R. Palaeomagnetism of the Karoo igneous rocks in southern Africa. S. Afr. J. Geol. 100, 195–212 (1997)

    Google Scholar 

  20. Layer, P. W., Kroner, A. & McWilliams, M. An Archean geomagnetic reversal in the Kaap Valley pluton, South Africa. Science 273, 943–946 (1996)

    Article  ADS  CAS  Google Scholar 

  21. Kroner, A. & Layer, P. W. Crust formation and plate motion in the early Archean. Science 256, 1405–1411 (1992)

    Article  ADS  CAS  Google Scholar 

  22. Wingate, M. T. D. A palaeomagnetic test of the Kaapvaal-Pilbara (Vaalbara) connection at 2.78 Ga. S. Afr. J. Geol. 101, 257–274 (1998)

    CAS  Google Scholar 

  23. Halgedahl, S. L., Day, R. & Fuller, M. The effect of cooling rate on the intensity of weak-field TRM in single-domain magnetite. J. Geophys. Res. 85, 3690–3698 (1980)

    Article  ADS  Google Scholar 

  24. McClelland Brown, E. Experiments on TRM intensity dependence on cooling rate. Geophys. Res. Lett. 11, 205–208 (1984)

    Article  Google Scholar 

  25. Valet, J. P. Time variations in geomagnetic intensity. Rev. Geophys. 41, 1004 (2003)

    Article  ADS  Google Scholar 

  26. Hulot, G., Eymin, C., Langlais, B., Mandea, M. & Olsen, N. Small-scale structure of the geodynamo inferred from Oersted and Magsat satellite data. Nature 416, 620–623 (2002)

    Article  ADS  CAS  Google Scholar 

  27. Sinnhuber, M. et al. A model study of the impact of magnetic field structure on atmospheric composition during solar proton events. Geophys. Res. Lett. 30, 1818 (2003)

    ADS  Google Scholar 

  28. Ozima, M. et al. Terrestrial nitrogen and noble gases in lunar soils. Nature 436, 655–659 (2005)

    Article  ADS  CAS  Google Scholar 

  29. Stevenson, D. J. Mars’ core and magnetism. Nature 412, 214–219 (2001)

    Article  ADS  CAS  Google Scholar 

  30. Gubbins, D., Alfe, D., Masters, G., Price, G. D. & Gillan, M. Gross thermodynamics of two-component core convection. Geophys. J. Int. 157, 1407–1414 (2004)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

We thank P. Layer, A. Smirnov and P. Doubrovine for discussions. This research was supported by NSF.

Author Contributions J.A.T., M.K.W. and D.B. took part in field studies, and J.A.T., R.D.C. and D.B. in technique development, experiments and data analysis.

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Authors and Affiliations

  1. Department of Earth and Environmental Sciences,,

    John A. Tarduno, Rory D. Cottrell & Dorothy Bauch

  2. Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA,

    John A. Tarduno

  3. School of Geological Sciences, University of KwaZulu-Natal, Durban 4041, South Africa,

    Michael K. Watkeys

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  1. John A. Tarduno
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Correspondence to John A. Tarduno.

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This file contains Supplementary Methods, Supplementary Figures S1-S6 wit Legends, Supplementary Tables 1-3 and additional references (PDF 331 kb)

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Tarduno, J., Cottrell, R., Watkeys, M. et al. Geomagnetic field strength 3.2 billion years ago recorded by single silicate crystals. Nature 446, 657–660 (2007). https://doi.org/10.1038/nature05667

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