Scientists found air stuck in a rock of 815 million years. Liberation brought surprises

Air release suggests that the earthly atmosphere had a much higher value of oxygen than expected 800 million years ago.

In 2016, an international investigators team made surprising discoveries about the composition of the earthly atmosphere more than 800 million years ago After discovering air stuck in an old rock. It was published in Geology.

The team led by geochemical Nigel Blamey analyzed microscopic gas bubbles Arrested within ancient salt-gum, or halite, of a drilling nucleus in Australia. Salt samples, dated 815 million years ago, contained “inclusions” – small ancient air bags preserved since their formation. Using a new method, scientists grinded halite in a vacuum chamber, releasing gas for analysis through two quadrupole mass spectrometers.

The results challenge old assumptions about oxygen levels in the neoproterozoic era. Previous models suggested that oxygen It was only about 2% of the earth’s atmosphere at that time. But Blamey’s team measured levels between 10.3% and 13.4%, which corresponds to approximately half of the current concentration of 20.9% and is a value much above expected.

“There was a lot of debate about what was the oxygen content 800 million years or more,” said Blamey. “We have developed a direct method to analyze these imprisoned fossil gases… and found that the oxygen level It was approximately half of what it is today.”

John Parnell, from the University of Aberdeen School of Geosciences, considered the discovery significant: “This is the first time oxygen in the air, which allowed the first animals to breathewas measured directly. Our results show that there was already enough oxygen for animals to thrive long before they arise. ”

The discovery raised questions about the moment and triggers of initial animal evolution. Higher oxygen levels may have sustained more complex life forms before it was thought before.

However, the results are not exempt from controversy. A separate reanalysis suggested that oxygen levels may have state closer to 6.6% Still high compared to the older but notably inferior estimates to Blamey’s numbers. Critics question whether dissolved gases may have distorted the original results, the.

Despite the debate, the team improved their techniques for dating and analyzing old gases imprisoned in Halite, paving the way for the deeper exploration of the Earth’s atmospheric history. The method can reveal new details about how oxygen levels influenced biological evolution and the climate along geological time scales.