erik simpson
2024-05-07 16:11:07 UTC
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.
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.