A two-billion-year history for the lunar dynamo
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e1700207.full.pdf
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Author(s)
Shuster, David L.
Tikoo-Schantz, Sonia M
Suavet, Clement Romain
Wang, Huapei
Weiss, Benjamin P.
Grove, Timothy L.
Date Issued
August 2017
Journal
Science Advances
Publisher
American Association for the Advancement of Science (AAAS)
Citation
Tikoo, Sonia M., Benjamin P. Weiss, David L. Shuster, Clément Suavet, Huapei Wang, and Timothy L. Grove. “A Two-Billion-Year History for the Lunar Dynamo.” Science Advances 3, no. 8 (August 2017): e1700207.
Version
Final published version
Abstract
Magnetic studies of lunar rocks indicate that the Moon generated a core dynamo with surface field intensities of ~20 to 110 μT between at least 4.25 and 3.56 billion years ago (Ga). The field subsequently declined to <~4 μT by 3.19 Ga, but it has been unclear whether the dynamo had terminated by this time or just greatly weakened in intensity. We present analyses that demonstrate that the melt glass matrix of a young regolith breccia was magnetized in a ~5 ± 2 μT dynamo field at ~1 to ~2.5 Ga. These data extend the known lifetime of the lunar dynamo by at least 1 billion years. Such a protracted history requires an extraordinarily long-lived power source like core crystallization or precession. No single dynamo mechanism proposed thus far can explain the strong fields inferred for the period before 3.56 Ga while also allowing the dynamo to persist in such a weakened state beyond ~2.5 Ga. Therefore, our results suggest that the dynamo was powered by at least two distinct mechanisms operating during early and late lunar history.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Attribution-NonCommercial 2.0 Generic (CC BY-NC 2.0)
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DOI of Published Version
https://doi.org/10.1126/SCIADV.1700207
