The Earth’s water may have actually originally formed by chemical reactions between silicon dioxide and fluid hydrogen deep within the planet’s mantle.
Research led by the University College Dublin offers a new theory as to how water may have originated on Earth, bucking the previous theory that suggests that comets that collided with the planet could have deposited large amounts of ice on Earth that later melted.
The researchers used computer simulations to find that reactions between high-pressure and high-temperature fluid hydrogen and silicon dioxide in quartz in the Earth’s upper mantle can form liquid water under the right conditions.
The research team tested the reaction at different temperatures and pressures typically found in the upper mantle 40 to 400 kilometers below the surface of the Earth.
The simulations showed that the silica and fluid hydrogen could form water when exposed to temperatures of just over 1400 degrees Celsius, at a pressure 20,000 times higher than the Earth’s atmospheric pressure.
Silica is abundant above and below the Earth’s surface, but the researchers were surprised to find that the water remained trapped inside the silica, which led to a massive buildup of pressure.
The researchers also believe the release of this pressure could have triggered earthquakes hundreds of kilometers below the Earth’s surface.
The new experiment support previous research on the reaction between silicon dioxide and liquid hydrogen by Japanese scientists in 2014.
“We were initially surprised to see in-rock reactions, but we then realized that we had explained the puzzling mechanism at the base of earlier Japanese experimental work finding water formation,” professor Niall English, UCD School of Chemical and Bioprocess Engineering, and the Materials, Energy and Water Simulations research group, said in a statement.
“We concluded that these findings help to rationalize, in vivid detail, the in-mantle genesis of water,” he added. “This is very exciting and in accord with very recent findings of an ‘ocean’s worth’ of water in the Earth’s mantle.”
The study was published in Earth and Planetary Science Letters.
