Sujet : Collapse of earth magnetic field coincides with animal radiation in the Ediacaran
De : eastside.erik (at) *nospam* gmail.com (erik simpson)
Groupes : talk.originsDate : 07. May 2024, 17:11:07
Autres entêtes
Organisation : University of Ediacara
Message-ID : <b2879933-6fe5-4c7a-afa9-2cb92bf55aad@gmail.com>
User-Agent : Mozilla Thunderbird
Near-collapse of the geomagnetic field may have contributed to atmospheric oxygenation and animal radiation in the Ediacaran Period
https://www.nature.com/articles/s43247-024-01360-4. (open access)
Abstract
Earth’s magnetic field was in a highly unusual state when macroscopic animals of the Ediacara Fauna diversified and thrived. Any connection between these events is tantalizing but unclear. Here, we present single crystal paleointensity data from 2054 and 591 Ma pyroxenites and gabbros that define a dramatic intensity decline, from a strong Proterozoic field like that of today, to an Ediacaran value 30 times weaker. The latter is the weakest time-averaged value known to date and together with other robust paleointensity estimates indicate that Ediacaran ultra-low field strengths lasted for at least 26 million years. This interval of ultra-weak magnetic fields overlaps temporally with atmospheric and oceanic oxygenation inferred from numerous geochemical proxies. This concurrence raises the question of whether enhanced H ion loss in a reduced magnetic field contributed to the oxygenation, ultimately allowing diversification of macroscopic and mobile animals of the Ediacara Fauna.
Note the "may have" of the title. Coincidences may or may not be telling us something, but it's an intriguing idea.