Synchronizing volcanic, sedimentary, and ice core records of Earth’s last magnetic polarity reversal
Reversal of Earth’s magnetic field polarity every 10(5) to 10(6) years is among the most far-reaching, yet enigmatic, geophysical phenomena. The short duration of reversals make precise temporal records of past magnetic field behavior paramount to understanding the processes that produce them. We co...
| Published in: | Science Advances |
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| Main Authors: | , , , |
| Format: | Text |
| Language: | English |
| Published: |
American Association for the Advancement of Science
2019
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| Subjects: | |
| Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6685714/ http://www.ncbi.nlm.nih.gov/pubmed/31457087 https://doi.org/10.1126/sciadv.aaw4621 |
| Summary: | Reversal of Earth’s magnetic field polarity every 10(5) to 10(6) years is among the most far-reaching, yet enigmatic, geophysical phenomena. The short duration of reversals make precise temporal records of past magnetic field behavior paramount to understanding the processes that produce them. We correlate new (40)Ar/(39)Ar dates from transitionally magnetized lava flows to astronomically dated sediment and ice records to map the evolution of Earth’s last reversal. The final 180° polarity reversal at ~773 ka culminates a complex process beginning at ~795 ka with weakening of the field, succeeded by increased field intensity manifested in sediments and ice, and then by an excursion and weakening of intensity at ~784 ka that heralds a >10 ka period wherein sediments record highly variable directions. The 22 ka evolution of this reversal suggested by our findings is mirrored by a numerical geodynamo simulation that may capture much of the naturally observed reversal process. |
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