Specialists from an American university came to this conclusion after examining rocks of the oceanic crust of 3.240 million years old.
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The Earth could be about 3.2 billion years ago a “water world” completely covered by a global ocean, suggests a new study published this Monday in the journal Nature Geoscience.
During the investigation, specialists from the University of Colorado Boulder (USA) Boswell Wing and Benjamin Johnson examined a segment of hydrothermally altered oceanic crust located in the Panorama district of the Pilbara craton in northwestern Australia. “There are no really old oceanic water samples now, but we have rocks that interacted with that seawater and remembered that interaction,” comment Johnson on the university website.
The scientists focused their efforts on finding two oxygen isotopes trapped in ancient rocks: oxygen-18 and oxygen-16, and discovered that the rocks of 3.240 million years (dated from the Archaic eon) were characterized by oxygen levels-18 more high than today. “Although these mass differences seem small, they are super sensitive,” Wing explains.
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The researcher points out that today’s land masses are covered by clay-rich soils that absorb the heaviest oxygen isotopes, such as oxygen-18, so the most likely explanation for that greater presence in the ancient oceans would stir up in that at that time there were no continents with land that absorbed those isotopes.
However, specialists clarify that this hypothesis does not mean that there were no microcontinents and small portions of land at the time. “We simply do not believe that there was a formation of continental soils on a global scale like the one we have today,” says Wing.
If these findings are confirmed by future studies, the new data could help scientists better understand how and where unicellular organisms first appeared on Earth, the authors note.
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