Earth’s history gets rewritten by a single drop of water

Using just the remaining of a single microscopic drop of ancient water, a group of researchers was able to rewrite the history of the Earth’s evolution and change the time when plate tectonics actually started on the planet.

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Plate tectonics is a continuous recycling process that directly or indirectly controls almost every function of the planet, such as atmospheric conditions, mountain building, natural hazards, the formation of mineral deposits and the maintenance of the oceans.

The large continental plates of the planet continuously move thanks to this process, while the top layers of the Earth are recycled into the mantle and replaced by new layers through processes such as volcanic activity.

The plate tectonics was initially thought to have started about 2.7 billion years, but that has now changed. A team of researchers used the microscopic leftovers of a drop of water that was transported into the Earth’s deep mantle to show this process actually started 600 million years before that.

“Plate tectonics constantly recycles the planet’s matter, and without it, the planet would look like Mars,” says Professor Allan Wilson, who was part of the research team. “Our research shows that plate tectonics started 3.3 billion years ago now coincides with the period that life started on Earth. It tells us where the planet came from and how it evolved.”

For their research, published in the journal Nature, the team analyzed a piece of rock melt, called komatiite – named after the Komati river near Barberton in Mpumalanga where it most commonly occurs – that are the leftovers from the hottest magma ever produced in the first quarter of Earth’s existence.

Despite most of the komatiites were obscured by later alteration and exposure to the atmosphere, small droplets of the molten rock were preserved in a mineral called olivine. This allowed the team to study a perfectly preserved piece of ancient lava as part of their research.

“We examined a piece of melt that was 0.01mm in diameter, and analyzed its chemical indicators such as H2O content, chlorine, and deuterium/hydrogen ratio, and found that Earth’s recycling process started about 600 million years earlier than originally thought,” said Wilson. “We found that seawater was transported deep into the mantle and then re-emerged through volcanic plumes from the core-mantle boundary.”

Earth is the only planet in our solar system that is shaped by plate tectonics and without it the planet would be uninhabitable. The research offers insight into the first stages of plate tectonics and the start of a stable continental crust.

“What is exciting is that this discovery comes at the 50th anniversary of the discovery of komatiites in the Barberton Mountain Land by Wits Professors, the brothers Morris and Richard Viljoen,” said Wilson.

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