Lowest level of geomagnetic field intensity

[jim mcnamara]

https://www.nature.com/articles/s41561-018-0288-0 (article is behind a paywall).
Popular Science version:
https://motherboard.vice.com/en_us/...-field-collapse-ediacaran-core-solidification

Using samples of rock from the Ediacarian period, 565 million years ago, it was determined that the Earth's magnetic field was about 10 times weaker than it is today.

The Earth’s core is thought to have been entirely liquid at some point, and the question of when it began to solidify has perplexed scientists for decades. Past estimates have ranged from 500 million years to 2.5 billion years ago. Bono’s team now presents evidence that nucleation began after 565 million years ago.

 

[trurle]

After reading popular article, i feel the authors may be jumping to conclusions about relation of iron core solidification and the start of bradichrone/superchron at end of Ediacarian. The knowledge bias is likely - Earth dynamo may had even weaker episodes before Ediacarian, we just do not know exactly due fragmentary paleomagnetic record in pre-Jurassic epoch.

 

[jim mcnamara]

@trurle If you can read the nature version there is discussion about this topic. There is on-going debate - ~2.0 billion year span of time's worth of hypotheses under discussion. So you are in good company.