Back to Search Start Over

A two-billion-year history for the lunar dynamo.

Authors :
Tikoo SM
Weiss BP
Shuster DL
Suavet C
Wang H
Grove TL
Source :
Science advances [Sci Adv] 2017 Aug 09; Vol. 3 (8), pp. e1700207. Date of Electronic Publication: 2017 Aug 09 (Print Publication: 2017).
Publication Year :
2017

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.

Details

Language :
English
ISSN :
2375-2548
Volume :
3
Issue :
8
Database :
MEDLINE
Journal :
Science advances
Publication Type :
Academic Journal
Accession number :
28808679
Full Text :
https://doi.org/10.1126/sciadv.1700207