Unknown Ways of How Diamonds Form Come to Light

New findings have revealed long unknown details about how carbon deep beneath the Earth’s surface is helping diamond formation in the Earth’s mantle.

The new theoretical model called the "Deep Earth Water" model allowed researchers to determine the chemical makeup of fluids in the Earth’s mantle, expelled from descending tectonic plates.

"These mantle fluids with dissolved organic carbon species could be creating diamonds in a previously unknown way," the authors said.

The Johns Hopkins University-led team in the US found that some of the fluids at 100 miles below the Earth’s surface contained the expected carbon dioxide and methane.

But others, those in equilibrium with diamonds, contained dissolved organic carbon species including a vinegar-like acetic acid.

"These high concentrations of dissolved carbon species, previously unknown at great depths in the Earth, suggest they are helping to ferry large amounts of carbon from into the overlying mantle wedge where they are likely to alter the mantle and affect the cycling of elements back into the Earth’s atmosphere," said Dimitri Sverjensky, geochemist and professor in the department of earth and planetary sciences.

Scientists have long believed diamond formation resulted through chemical reactions starting with either carbon dioxide or methane.

Sverjensky and his team also demonstrated that in addition to the carbon dioxide and methane, there exists a rich variety of organic carbon species that could spark microbial life.

"It is a very exciting possibility that deep fluids beneath the Earth’s surface might transport building blocks for life into the shallow Earth. This may be a key to the origin of life itself," Sverjensky said.

The article was published in the journal Nature Geoscience.

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