Vast Bodies Of Water Underground? Water-Rich Gem May Yield New Discovery
In his classic, Journey to the Center of the Earth, Jules Verne describes deep oceans in the bowels of the earth. For many years scientists had mixed theories about the composition of interior Earth and whether it's dry or full of water. But now, the discovery of a water-rich gem, which may have come from very deep inside the Earth proves Jules Verne's theory to be correct, according to a press release Wednesday.
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The first ever terrestrial sample of this water-rich mineral called ringwoodite was discovered by Graham Pearson, a diamond scientist at the University of Alberta (U of A). He, along with an international team of scientists analyzed the mineral and found in it water, which amounts to 1.5 percent of the mineral's weight. This finding confirms the theory that vast volumes of water is trapped 410 to 660 kilometers beneath the Earth, between the upper and lower mantle.
"This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area," said Pearson, a professor in the Faculty of Science, whose findings will be published March 13 in Nature. "That particular zone in the Earth, the transition zone, might have as much water as all the world's oceans put together."
Scientists believe that ringwoodite, a form of mineral peridot or gemstone, is present in large quantities in the transition zone where the pressure is very high. It has been found in meteorites but scientists have always been on a lookout for terrestrial samples, which are difficult to find because of the great depths in which they exist.
But Pearson and his team got lucky when they found their sample in 2008 in the Juina area of Mato Grosso, Brazil. The diamond, which contained the ringwoodite was excavated by miners from a shallow river bed. It was brought to the surface by a volcanic rock called kimberlite that is formed deep within the mantle of the Earth.
What Pearson and his team initially got was a three-millimeter-wide, dirty and inexpensive-looking, brown diamond. The ringwoodite was buried beneath the surface of the diamond, invisible to the naked eye. It would have remained such had it not been for Pearson's graduate student, John McNeill, who found it in 2009."It's so small, this inclusion, it's extremely difficult to find, never mind work on," Pearson said, "so it was a bit of a piece of luck, this discovery, as are many scientific discoveries."
But the scientists had to perform several analysis, including Raman and infrared spectroscopy and X-ray diffraction, before confirming it to be ringwoodite. The critical water measurements were performed at Pearson's Arctic Resources Geochemistry Laboratory at the U of A, which is part of the Canadian Centre for Isotopic Microanalysis. This centre also has the distinction of having the world's largest academic diamond research group.
Scientists from different parts of the world have collaborated for this research. For Pearson and scientists like him, it's a discovery of a lifetime. Understanding the composition of ringwoodite and knowing that the earth's transition zone is filled with water opens a whole new chapter in the study of volcanoes, tectonic plate shifts, molten rocks, and cooling of the Earth's crust.
Pearson said, "One of the reasons the Earth is such a dynamic planet is the presence of some water in its interior. Water changes everything about the way a planet works."
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