Publication Date:
2019
Description:
〈p〉Reversal of Earth’s magnetic field polarity every 10〈sup〉5〈/sup〉 to 10〈sup〉6〈/sup〉 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 〈sup〉40〈/sup〉Ar/〈sup〉39〈/sup〉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. 〈/p〉
Electronic ISSN:
2375-2548
Topics:
Natural Sciences in General
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