MagNetZ with Jay Shah (2021/03/31) - Evidence for an intermittent lunar dynamo
Channel: MagNetZ
Date: 2021-04-06

The video is also available for download at: https://earthref.org/ERDA/2465/
and can be referenced with the doi: 10.7288/V4/ERDA/2465

Title: Evidence for an intermittent lunar dynamo
Author: Jay Shah from Massachusetts Institute of Technology, USA
Author Website: https://eapsweb.mit.edu/people/jayshah

Paleointensity data suggest the presence of a lunar dynamo with a surface intensity reaching tens of µT during the period 4.25 to 3.56 Ga and subsequently declining to several µT during the following ~2 billion years. However, the lunar energy budget does not appear to be able to continuously power such a strong dynamo for so long. A proposed solution to this conundrum is that the lunar dynamo was in fact highly time-variable or even intermittently active during this period. However, until now, there has been no Thellier paleointensity data from Apollo lunar samples to support a time-variable dynamo. Using our newly developed oxygen fugacity controlled atmosphere thermal demagnetizer, we report new paleointensity data from lunar regolith breccias showing near-zero (less than 0.5 µT) paleointensity at 3.3 ± 0.43 Ga and at 1.7 ± 0.43 Ga. This supports the proposal that the average field may have been significantly weaker than implied by the highest paleointensities, consistent with the expected energy budget for the lunar core.