The Brunhes–Matuyama reversal, named after Bernard Brunhes and Motonori Matuyama, was a geologic event, approximately 781,000 years ago, when the Earth's magnetic field last underwent reversal.[1][2] Estimations vary as to the abruptness of the reversal. A 2004 paper estimated that it took over several thousand years;[3] a 2010 paper estimated that it occurred more quickly,[4][5][6] perhaps within a human lifetime;[7] a 2019 paper estimated that the reversal lasted 22,000 years.[8][9]

The apparent duration at any particular location can vary by an order of magnitude, depending on geomagnetic latitude and local effects of non-dipole components of the Earth's field during the transition.[3]

The Brunhes–Matuyama reversal is a marker for the Global Boundary Stratotype Section and Point (GSSP) defining the base of the Chibanian Stage and Middle Pleistocene Subseries at the Chiba section, Japan, which was officially ratified in 2020 by the International Union of Geological Sciences.[10][11] It is useful in dating ocean sediment cores and subaerially erupted volcanics.

There is a highly speculative theory that connects this reversal event to the large Australasian strewnfield (c. 790,000 years ago),[12] although the causes of the two are almost certainly unconnected and only coincidentally happened around the same time. Adding to the data is the large African Bosumtwi impact event (c. 1.07 million years ago) and the later Jaramillo reversal (c. 1 million years ago), another pair of events which has not gone unnoticed.[13]

See also

References

  1. ↑ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G., eds. (2004). A Geological Time Scale (3rd ed.). Cambridge: Cambridge University Press. p. 28. ISBN 978-0521786737.
  2. ↑ "Global chronostratigraphical correlation table for the last 2.7 million years". International Commission on Stratigraphy. Retrieved 31 March 2014.
  3. 1 2 Bradford M. Clement (8 April 2004). "Dependence of the duration of geomagnetic polarity reversals on site latitude". Nature. 428 (6983): 637–40. Bibcode:2004Natur.428..637C. doi:10.1038/nature02459. PMID 15071591. S2CID 4356044.
  4. ↑ Witze, Alexandra (Sep 2, 2010). "Geomagnetic field flip-flops in a flash". ScienceNews. Archived from the original on 27 September 2012. Retrieved 3 September 2010.
  5. ↑ Coe, R.S.; Prévot, M.; Camps, P. (20 April 1995). "New evidence for extraordinarily rapid change of the geomagnetic field during a reversal" (PDF). Nature. 374 (6524): 687. Bibcode:1995Natur.374..687C. doi:10.1038/374687a0. S2CID 4247637. Archived from the original (PDF) on 31 July 2010.
  6. ↑ Bogue, S. W.; Glen, J. M. G. (2010). "Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow". Geophysical Research Letters. 37 (21): L21308. Bibcode:2010GeoRL..3721308B. doi:10.1029/2010GL044286. S2CID 129896450.
  7. ↑ Leonardo Sagnotti; Giancarlo Scardia; Biagio Giaccio; Joseph C. Liddicoat; Sebastien Nomade; Paul R. Renne; Courtney J. Sprain (21 July 2014). "Extremely rapid directional change during Matuyama-Brunhes geomagnetic polarity reversal". Geophys. J. Int. 199 (2): 1110–1124. Bibcode:2014GeoJI.199.1110S. doi:10.1093/gji/ggu287.
  8. ↑ Singer, Brad S.; Jicha, Brian R.; Mochizuki, Nobutatsu; Coe, Robert S. (August 7, 2019). "Synchronizing volcanic, sedimentary, and ice core records of Earth's last magnetic polarity reversal". Science Advances. 5 (8): eaaw4621. Bibcode:2019SciA....5.4621S. doi:10.1126/sciadv.aaw4621. ISSN 2375-2548. PMC 6685714. PMID 31457087.
  9. ↑ Science, Passant; Rabie (August 7, 2019). "Earth's Last Magnetic-Pole Flip Took Much Longer Than We Thought". Space.com. Retrieved August 8, 2019.
  10. ↑ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Archived from the original on 15 November 2012. Retrieved 31 March 2014.
  11. ↑ Head, Martin J. (2021). "Review of the Early–Middle Pleistocene boundary and Marine Isotope Stage 19". Progress in Earth and Planetary Science. Progress in Earth and Planetary Science (2021) 8(1): 50. 8 (1): 50. Bibcode:2021PEPS....8...50H. doi:10.1186/s40645-021-00439-2. PMC 8549982. PMID 34722119.
  12. ↑ Glass, B. P., Swincki, M. B., & Zwart, P. A. (1979). "Australasian, Ivory Coast and North American tektite strewnfields – Size, mass and correlation with geomagnetic reversals and other earth events" Lunar and Planetary Science Conference, 10th, Houston, Tex., March 19–23, 1979, pp. 2535–2545.
  13. ↑ Glass, B. P., Swincki, M. B., & Zwart, P. A. (1979). "Australasian, Ivory Coast and North American tektite strewnfields - Size, mass and correlation with geomagnetic reversals and other earth events" Lunar and Planetary Science Conference, 10th, Houston, Tex., March 19–23, 1979, p. 2535-2545.

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