Year: 2026
Type: article
Abstract: One of the most intriguing attributes of Earth's magnetic field is that it reverses polarity. Previous palaeomagnetic records mainly from the last ~17 million years indicate that the reversal process typically occurs over ten thousand or fewer years. Here we present an exceptionally resolved deep sea sedimentary palaeomagnetic record that captures two polarity transitions that occurred ~40 million years ago. These transitions occur over 18 and 70 thousand years and are much longer than the typical 10 kyr duration for younger reversals. Longer-duration transitions like these are calculated in numerical geodynamo models, suggesting that variable reversal durations are an intrinsic property of the geodynamo. This variability predicts that polarity transition durations can be much longer than 10 kyr. Occasional prolonged intervals of transitional, and weaker, geomagnetic fields would have exposed Earth's Eocene environments to greater high-energy radiation from the sun for longer intervals of time, with potential impacts on biota.
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,490
Awards: Astronomical Solutions over Geological Time, G343868992, G434337789, Billion-year scale geodynamo evolution associated with dynamics of inner core growth, Early evolution of the geomagnetic field induced by a basal magma ocean dynamo, 交差対称性相互作用に基づく惑星の特異な磁場構造と内部進化過程の理解, Investigating long-term variation in intensity of the paleomagnetic field during a period of low reversal frequency - new constraint on the outer core process
OpenAlex ID: W7124929789