This looks god so I read the article. It seemms to me there is a fundamental flaw in this paper so I surprised it is published in Nature.
It may be the news story does not contain the crucial information but the story is a load of old crock! My criticism is this. The evidence is based on a stone found in river gravel in Brazil. They tell us that the only other place where it has been found is in meteorites. So how do they know their sample is not from a meteorite and that it MUST HAVE COME FROM THE TRANSITION ZONE. Until I see that evidence to rule out a meteorite then the case is unproven.
Earth may have a 'secret' reservoir of water, scientists say
AFP March 13, 2014 7:50AM
Print Save for later
Share
expand
Share on facebook
Your Friends' Activity
Hi Desmond Discover news with your friends. Give it a try. To get going, simply connect with your favourite social network: Facebook
A HUNDRED and fifty years ago, in journey to the Centre of the Earth, French science-fiction forerunner Jules Verne pictured a vast sea that lay deep under our planet's surface.
Now, that strange and haunting image has found an unexpected echo in a scientific paper, with the evidence provided by a rare and elusive mineral named after an Australian geologist.
Writing in the journal Nature, scientists said the mineral they'd found pointed to the existence of a vast reservoir deep in Earth's mantle, 400-600 kilometres beneath our feet.
It may hold as much water as all the planet's oceans combined, they believe.
The evidence comes from a water-loving mineral called ringwoodite that came from the so-called transition zone sandwiched between the upper and lower layers of Earth's mantle, they said.
Ringwoodite is named after Australian geologist Ted Ringwood, who theorised that a special mineral was bound to be created in the transition zone because of the ultra-high pressures and temperatures there.
Analysis shows that a whopping 1.5 per cent of the rock comprises molecules of water.
The find backs once-contested theories that the transition zone, or at least significant parts of it, is water-rich, the investigators said.
"This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area," said Graham Pearson of Canada's University of Alberta, who led the research.
"That particular zone in the Earth, the transition zone, might have as much water as all the world's oceans put together."
A piece of ringwoodite has been a long-sought goal. It would resolve a long-running debate about whether the poorly-understood transition zone is bone-dry or water-rich.
But, until now, ringwoodite has only ever been found in meteorites. Geologists had simply been unable to delve deep enough to find any sample on Earth.
Good fortune, though, changed all this.
In 2008, amateur gem-hunters digging in shallow river gravel in the Juina area of Mato Grosso, Brazil, came across a tiny, grubby stone called a brown diamond.
Measuring just three millimetres across and commercially worthless, the stone was acquired by the scientists when they were on a quest for other minerals.
But the accidental acquisition turned out to be a bonanza.
In its interior, they found a microscopic trace of ringwoodite - the very first terrestrial evidence of the ultra-rare rock.
"It's so small, this inclusion, it's extremely difficult to find, never mind work on," Pearson said in a press release, paying tribute to the diligent work of grad student John McNeill.
"It was a bit of a piece of luck, this discovery, as are many scientific discoveries."
The team theorise that the brown diamond rocketed to the surface during a volcanic eruption, hitchhiking in a stream of kimberlite, the deepest of all volcanic rocks.
Years of analysis, using spectroscopy and X-ray diffraction, were needed in specialised labs to confirm the find officially as ringwoodite.
Scientists have debated for decades about whether the transition zone has water, and if so, how much of the precious stuff there might be.
None, though, has embraced Verne's fancy of a subterranean sea with a rocky coastline dotted with forests of giant mushrooms and petrified trees.
Hans Keppler, a geologist at the University of Bayreuth in Germany, cautioned against extrapolating the size of the subterranean water find from a single sample of ringwoodite.
And he also said the water was likely to be locked up in specific rocks, in a molecular form called hydroxyl.
"In some ways it is an ocean in Earth's interior, as visualised by Jules Verne ... although not in the form of liquid water," Keppler said in a commentary also published by Nature.
The implications of the discovery are profound, Pearson suggested. If water exists in huge volumes beneath Earth's crust, it is bound to have a big impact on the mechanics of volcanoes and the movement of tectonic plates.
"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," said Pearson.
