How life on Earth started 2 bn years ago

Last Updated: Monday, November 18, 2013 - 10:55

Washington: Two billion years ago, the Earth system was recovering from perhaps the single-most profound modification of its surface environments: the oxygenation of the atmosphere and oceans, which led to a series of major changes in global biogeochemical cycles.

According to the team around Aivo Lepland of the Norwegian Geological Survey NGU, this also resulted in the distribution of one of life`s key elements, phosphorous.

The researchers studied the unique organic-rich Zaonega rock formation preserved in Carelia, NW Russia, with an age of around two billion years.

Co-author Richard Wirth of the GFZ German Research Centre for Geosciences, who analyzed the rock samples with an electron microscope, said that the formation of Earth`s earliest phosphorites was influenced strongly, if not controlled completely, by the activity of sulfur bacteria.

He said that this activity occurred in an oil field setting that had been influenced by active volcanism and associated venting and seeping.

In the modern world, sulfur bacteria inhabit upwelling vent and seep areas known as " Black Smokers " and mediate phosphorite formation.

The authors therefore conclude that the formation of the earliest worldwide phosphorites 2 billion years ago can be linked to the establishment of sulfur bacteria habitats, triggered by the oxygenation of the Earth.

The study has been published online in journal Nature Geoscience.

First Published: Monday, November 18, 2013 - 10:52
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