Geomagnetic dipole strength and reversal rate over the past two million years

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Abstract

Independent records of relative magnetic palaeointensity from sediment cores in different areas of the world can be stacked together to extract the evolution of the geomagnetic dipole moment1,2 and thus provide information regarding the processes governing the geodynamo. So far, this procedure has been limited to the past 800,000 years (800 kyr; ref. 3), which does not include any geomagnetic reversals. Here we present a composite curve that shows the evolution of the dipole moment during the past two million years. This reconstruction is in good agreement with the absolute dipole moments derived from volcanic lavas, which were used for calibration. We show that, at least during this period, the time-averaged field was higher during periods without reversals but the amplitude of the short-term oscillations remained the same. As a consequence, few intervals of very low intensity, and thus fewer instabilities, are expected during periods with a strong average dipole moment, whereas more excursions and reversals are expected during periods of weak field intensity. We also observe that the axial dipole begins to decay 60–80 kyr before reversals, but rebuilds itself in the opposite direction in only a few thousand years.

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Figure 1: Various stacks obtained for the period 0.6–2 Myr ago.
Figure 2: Composite Sint-2000 record depicting the evolution of the field intensity during the past 2 Myr.
Figure 3: Time-averaged dipole moment calculated within sliding windows of different sizes, as a function of the number of reversals contained within each window.
Figure 4: Field intensity variations across the five reversals occurring during the past 2 Myr.

References

  1. 1

    Guyodo, Y. & Valet, J. P. Relative variations in geomagnetic intensity from sedimentary records: the past 200 thousand years. Earth Planet. Sci. Lett. 143, 23–26 (1996)

  2. 2

    Laj, C., Kissel, C., Mazaud, M., Channell, J. E. T. & Beer, J. North Atlantic paleointensity stack since 75 ka (NAPIS 75) and the duration of the Laschamp event. Phil. Trans. R. Soc. Lond. A 358, 1009–1025 (2000)

  3. 3

    Guyodo, Y. & Valet, J. P. Global changes in intensity of the Earth's magnetic field during the past 800 kyr. Nature 399, 249–252 (1999)

  4. 4

    Gee, J., Cande, S. C., Hildebrand, J. A., Donnelly, J. A. & Parker, R. L. Geomagnetic intensity variations over the past 780 kyr obtained from near-seafloor magnetic anomalies. Nature 408, 827–832 (2000)

  5. 5

    Pouliquen, G., Gallet, Y., Dyment, J., Patriat, P. & Tamura, C. A geomagnetic record over the last 4 million years from deep-tow magnetic profiles across the Central Indian Ridge. J. Geophys. Res. 106, 10941–10960 (2001)

  6. 6

    Frank, M. A 200 kyr record of cosmogenic radionuclide production rate and geomagnetic field intensity from 10Be in globally stacked deep-sea sediments. Phil. Trans. R. Soc. Lond. A 358, 1089–1107 (2000)

  7. 7

    Baumgartner, S. et al. Geomagnetic modulation of the 36Cl flux in the Grip ice core, Greenland. Science 279, 1330–1332 (1998)

  8. 8

    Valet, J.-P., Meynadier, L., Bassinot, F. C. & Garnier, F. Relative paleointensity across the last geomagnetic reversal from sediments of the Atlantic, Indian and Pacific oceans. Geophys. Res. Lett. 21, 485–488 (1994)

  9. 9

    Dinares-Turell, J., Sagnotti, L. & Roberts, A. P. Relative geomagnetic paleointensity from the Jaramillo subchron to the Matuyama/Brunhes boundary as recorded in a Mediterranean piston core. Earth Planet. Sci. Lett. 194, 327–341 (2002)

  10. 10

    Laj, C. & Kissel, C. Geomagnetic field intensity and reversals for the last 1.8 Ma from a central equatorial Pacific core. Geophys. Res. Lett. 23, 3393–3396 (1996)

  11. 11

    Channell, J. E. T. & Kleiven, H. F. Geomagnetic paleointensity and astrochronological ages for the Matuyama-Brunhes boundary and the boundaries of the Jaramillo subchron: paleomagnetic and oxygen isotope records from ODP site 983. Phil. Trans. R. Soc. Lond. A 358, 1027–1047 (2000)

  12. 12

    Guyodo, Y., Richter, C. & Valet, J. P. Paleointensity record from Pleistocene sediments off the California Margin. J. Geophys. Res. 104, 22953–22964 (1999)

  13. 13

    Guyodo, Y., Acton, G. D., Brachfeld, S. & Channell, J. E. T. A sedimentary paleomagnetic record of the Matuyama chron from the western Antarctic margin. Earth Planet. Sci. Lett. 191, 61–74 (2001)

  14. 14

    Hayashida, A., Verosub, K. L., Heider, F. & Leonhardt, R. Magnetostratigraphy and relative paleointensity of late Neogene sediments at ODP leg 167 site 1010 off Baja California. Geophys. J. Int. 139, 829–840 (1999)

  15. 15

    Horng, C. S., Roberts, A. P. & Liang, W.-T. Astronomically tuned record of relative geomagnetic paleointensity from the western Philippine sea. J. Geophys. Res. 108, 2059, doi:10.1029/2001JB001698 (2003)

  16. 16

    Kent, D. V. & Opdyke, N. D. Paleomagnetic field intensity recorded in a Brunhes epoch deep-sea sediment core. Nature 266, 156–159 (1977)

  17. 17

    Kok, Y. S. & Tauxe, L. A relative geomagnetic paleointensity stack from Ontong-Java plateau sediments for the Matuyama. J. Geophys. Res. 104, 25401–25413 (1999)

  18. 18

    Meynadier, L., Valet, J.-P., Bassinot, F. C., Shackleton, N. & Guyodo, Y. Asymmetrical saw-tooth pattern of the geomagnetic field intensity from equatorial sediments in the Pacific and the Indian oceans. Earth Planet. Sci. Lett. 126, 109–127 (1994)

  19. 19

    Sato, T., Kikuchi, H., Nakashizuka, M. & Okada, M. Quaternary geomagnetic field intensity: constant periodicity or variable period? Geophys. Res. Lett. 25, 2221–2224 (1998)

  20. 20

    Schneider, D. A., Kent, D. V. & Mello, G. A. A high-resolution marine sedimentary record of geomagnetic intensity during the Brunhes chron. Earth Planet. Sci. Lett. 111, 395–405 (1992)

  21. 21

    Valet, J.-P. & Meynadier, L. Geomagnetic field intensity and reversals during the past four million years. Nature 366, 234–238 (1993)

  22. 22

    Valet, J.-P. Time variations in geomagnetic intensity. Rev. Geophys. 41(1), 1004 (2003)

  23. 23

    Guyodo, Y. & Channell, J. E. T. Effects of variable sedimentation rates and age errors on the resolution of sedimentary paleointensity records. Geochem. Geophys. Geosyst. 10, doi:1029/2001GC000211 (2002)

  24. 24

    McMillan, D. G., Constable, C. G. & Parker, R. L. Assessing the dipolar signal in stacked paleointensity records using a statistical error model and geodynamo simulations. Physics Earth Planet. Inter. 145, 37–54 (2004)

  25. 25

    Guyodo, Y. & Valet, J. P. A comparison of relative paleointensity records of the Matuyama chron for the period 0.75–1.25 Ma. Phys. Earth. Planet. Inter. (in the press)

  26. 26

    Guyodo, Y., Gaillot, P. & Channell, J. E. T. Wavelet analysis of relative geomagnetic paleointensity at ODP Site 983. Earth Planet. Sci. Lett. 184, 109–123 (2000)

  27. 27

    Perrin, M. & Schnepp, E. IAGA paleointensity database: distribution and quality of the dataset. Phys. Earth Planet. Inter. 147(2–3), 255–267 (2004)

  28. 28

    Constable, C. G., Tauxe, L. & Parker, R. L. Analysis of 11 Myr of geomagnetic intensity variation. J. Geophys. Res. 103, 17735–17748 (1998)

  29. 29

    Quidelleur, X., Gillot, P.-Y., Carlut, J. & Courtillot, V. The age and duration of the Matuyama–Brunhes transition from new K–Ar data from La Palma (Canary Islands) and revisited 40Ar/39Ar ages. Earth Planet. Sci. Lett. 168, 233–242 (1999)

  30. 30

    Meynadier, L. & Valet, J.-P. Post-depositional realignment of magnetic grains and asymmetrical saw-toothed pattern of magnetization intensity. Earth Planet. Sci. Lett. 140, 123–132 (1996)

  31. 31

    Mazaud, A. Saw-tooth variation in magnetic intensity profiles and delayed acquisition of magnetization in deep sea cores. Earth Planet. Sci. Lett. 139, 379–386 (1996)

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Acknowledgements

This work was supported by the INSU-CNRS programme ‘Dynamique et Evolution de la Terre Interne’.

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Correspondence to Jean-Pierre Valet.

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Valet, J., Meynadier, L. & Guyodo, Y. Geomagnetic dipole strength and reversal rate over the past two million years. Nature 435, 802–805 (2005) doi:10.1038/nature03674

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