Brunhes–Matuyama reversal explained

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.

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.

See also

• Bosumtwi impact event
• Gauss–Matuyama reversal
• Geomagnetic reversal
• Jaramillo reversal
• List of geomagnetic reversals

Further reading

• Behrendt, J.C., Finn, C., Morse, L., Blankenship, D.D. "One hundred negative magnetic anomalies over the West Antarctic Ice Sheet (WAIS), in particular Mt. Resnik, a subaerially erupted volcanic peak, indicate eruption through at least one field reversal" University of Colorado, U.S. Geological Survey, University of Texas. (U.S. Geological Survey and The National Academies); USGS OF-2007-1047, Extended Abstract 030. 2007.

Notes and References

1. Book: Ogg . James G. . Smith . Alan G. . Gradstein. Felix M. . A Geological Time Scale . limited . 2004. Cambridge University Press. Cambridge . 978-0521786737. 28. 3rd .
2. Web site: Global chronostratigraphical correlation table for the last 2.7 million years. International Commission on Stratigraphy. 31 March 2014.
3. Bradford M.. Clement. Dependence of the duration of geomagnetic polarity reversals on site latitude. 8 April 2004. Nature. 428. 15071591. 6983. 10.1038/nature02459. 637–40. 2004Natur.428..637C . 4356044.
4. Web site: Witze. Alexandra. Geomagnetic field flip-flops in a flash. ScienceNews. 3 September 2010. Sep 2, 2010. 27 September 2012. https://web.archive.org/web/20120927145706/http://www.sciencenews.org/view/generic/id/62947/title/Geomagnetic_field_flip-flops_in_a_flash. dead.
5. R.S. . Coe . M. . Prévot . P. . Camps . New evidence for extraordinarily rapid change of the geomagnetic field during a reversal . Nature . 374 . 20 April 1995 . 687 . 10.1038/374687a0 . 6524 . 1995Natur.374..687C . 4247637 . dead . https://web.archive.org/web/20100731030313/http://es.ucsc.edu/~rcoe/eart110c/Coeetal_Steens_Nature95.pdf . 31 July 2010 .
6. Bogue . S. W. . J. M. G. . Glen . 129896450 . 2010 . L21308 . Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow . 37 . 21 . Geophysical Research Letters . 10.1029/2010GL044286 . 2010GeoRL..3721308B.
7. Leonardo. Sagnotti. Giancarlo. Scardia. =Biagio. Giaccio. Joseph C.. Liddicoat. Sebastien. Nomade. Paul R.. Renne. Courtney J.. Sprain. Extremely rapid directional change during Matuyama-Brunhes geomagnetic polarity reversal. 21 July 2014. Geophys. J. Int.. 199. 2. 10.1093/gji/ggu287. 1110–1124. 2014GeoJI.199.1110S. free.
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. en. 5. 8. eaaw4621. 10.1126/sciadv.aaw4621. 31457087. 6685714. 2019SciA....5.4621S. 2375-2548. free.
9. Web site: Earth's Last Magnetic-Pole Flip Took Much Longer Than We Thought. Rabie. Passant. 2019-08-07. Space.com. en. 2019-08-08. mdy-all.
10. Web site: Global Boundary Stratotype Section and Point. International Commission of Stratigraphy. 31 March 2014. dead. https://web.archive.org/web/20121115175854/http://www.stratigraphy.org/GSSP/index.html. 15 November 2012.
11. Head . Martin J. . Review of the Early–Middle Pleistocene boundary and Marine Isotope Stage 19 . Progress in Earth and Planetary Science . 2021 . 8 . 1 . 50 . Progress in Earth and Planetary Science (2021) 8(1): 50. . 10.1186/s40645-021-00439-2. 34722119 . 8549982 . 2021PEPS....8...50H . free .
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.