"Billion-year-old lake deposit yields clues to Earth's" Topic

… ancient biosphere.

"A sample of ancient oxygen, teased out of a 1.4 billion-year-old evaporative lake deposit in Ontario, provides fresh evidence of what the Earth's atmosphere and biosphere were like during the interval leading up to the emergence of animal life.

The findings, published in the journal Nature, represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years. The results support previous research suggesting that oxygen levels in the air during this time in Earth history were a tiny fraction of what they are today due to a much less productive biosphere.

"It has been suggested for many decades now that the composition of the atmosphere has significantly varied through time," says Peter Crockford, who led the study as a PhD student at McGill University. "We provide unambiguous evidence that it was indeed much different 1.4 billion years ago."…."
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Amicalement
Armand

Nice. Here is the abstract:

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This is in the Sibley Basin, roughly between Lake Superior and Lake Nipigon……not far from the Minnesota border.

Glad you enjoyed it my friend!. (smile)

Amicalement
Armand