Study suggests hydrogen, oxygen, water and carbon dioxide generated in Earth's mantle

October 3, 2017 by Louisa Kellie
Earth's Mantle. Credit: Assist Basu

Research from the University of Texas at Arlington and the Wadia Institute of Himalayan Geology suggests that hydrogen, oxygen, water and carbon dioxide are being generated in the earth's mantle hundreds of kilometers below the earth's surface.

"This discovery is important as it shows how earth's planetary evolution may have happened," said Asish Basu, UTA professor of earth and environmental sciences and co-author of the cover paper published in Geology in August.

The researchers focused their attention on a seven-kilometer thick portion of the earth's upper now found in the High Himalayas, at altitudes between 12,000 and 16,000 feet. This section of the mantle was pushed upwards to the top of the mountains as a result of the Indian Plate pushing north into Asia, displacing the ancient Tethys ocean floor and underlying mantle to create the Himalayan Mountain Belt around 55 million years ago.

"This is important as it means that we can analyze the nature of the mantle under the earth's crust, at depths where drilling cannot reach," Basu explained. "One key initial discovery was finding microdiamonds whose originated in the mantle transition zone, at depths between 410 and 660 kilometers below the earth's surface."

By studying the host rocks and associated minerals, the scientists had a unique opportunity to probe the nature of the deep mantle. They found primary hydrocarbon and hydrogen fluid inclusions along with microdiamonds by using Laser Raman Spectroscopic study. The discovery also showed that the environment in the deep depths where the diamond is formed is devoid of oxygen.

The researchers suggest that during the advective transport or mantle up-welling into shallower mantle zones, the hydrocarbon fluids become oxidized and precipitate diamond, a mechanism that may also be responsible for forming larger diamonds like the world's most valuable, Koh-i-Noor or Mountain of Light diamond, now in the Queen of England's crown.

"We also found that the deep mantle upwelling can oxidize oxygen-impoverished fluids to produce water and carbon dioxide that are well-known to produce melting," said Souvik Das, UTA post-doctoral research scholar.

"This means that many of the key compounds affecting evolution like and water are generated within the mantle," he added.

Explore further: Iron carbonates in Earth's mantle help form diamonds

More information: S. Das et al, In situ peridotitic diamond in Indus ophiolite sourced from hydrocarbon fluids in the mantle transition zone, Geology (2017). DOI: 10.1130/G39100.1

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mikpolock
1 / 5 (1) Oct 04, 2017
Just as I've always thought. Celestial objects don't need to wait for generations of stars to live and die just to get their heavier elements. Nucleosynthesis is carried out by each, individual object. There is no such thing as accretion from gas and dust. All celestial objects started as masses of fusion powered plasma. Our moon, earth, Jupiter, the sun, everything. Heavier elements are created as the object cools and creates a crust. We are Earth dust, not start dust.
434a
5 / 5 (1) Oct 04, 2017
Just as I've always thought. Celestial objects don't need to wait for generations of stars to live and die just to get their heavier elements. Nucleosynthesis is carried out by each, individual object. There is no such thing as accretion from gas and dust. All celestial objects started as masses of fusion powered plasma. Our moon, earth, Jupiter, the sun, everything. Heavier elements are created as the object cools and creates a crust. We are Earth dust, not start dust.


Take a look at the graphic at the top of the article. See the equations? See anything that looks like nucleosynthesis? No, it's all (geo)chemistry. All it's saying is that minerals - composed of elements made during novae - are reacting under extremes of temperature and pressure found in the Earth's mantel. We now have a possible mechanism in which planetary evolution can provide the chemicals we identify with life.
mikpolock
2.3 / 5 (3) Oct 05, 2017
Nucleosynthesis took place long ago as our planet was developing a crust. It's only happening deep in the earth now. When the crust of an object forms, all of the nucleosynthesis is relegated to underneath the crust. Jupiter is forming its crust now. It is performing nucleosynthesis near the surface as we speak. The crust is there because shoemaker levy left marks on the surface for months. This wouldn't happen if it was all gas.
Everything starts as plasma and cools from there.

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