From 600 to 540 million years ago, the planet hosted only soft-bodied organisms known as Ediacaran fauna. The fossil evidence indicates a significant diversification of these life forms between 575 and 565 million years ago, a period that aligns with a notable rise in oxygen levels. Although the cause of this oxygen increase has been uncertain, the study offers new insights.
John Tarduno and his team analyzed the magnetic properties of 21 plagioclase crystals from a 591-million-year-old rock formation in Brazil. These crystals harbor tiny magnetic minerals that record the magnetic field strength at their formation. Their analysis revealed that the magnetic field at the time was the weakest recorded, nearly 30 times weaker than today's magnetic field and significantly weaker than fields recorded two billion years ago.
This prolonged period of magnetic weakness, lasting at least 26 million years, coincided with the period of increased oxygen from 575 to 565 million years ago. The researchers theorize that the reduced magnetic field might have allowed more hydrogen to escape Earth's atmosphere, consequently enriching it with oxygen. This enriched oxygen environment could have supported the diversification and increased complexity of life forms during this time.
Research Report:Near-collapse of the geomagnetic field may have contributed to atmospheric oxygenation and animal radiation in the Ediacaran Period
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University of Rochester
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