Yet again our planet Earth proves its reticent nature once again. Scientists have discovered a vast reservoir of water underneath the Earth’s mantle they say could be larger than all the planet’s oceans combined.
Canadian scientists found an elusive mineral pointing to the existence of a vast reservoir hidden deep in the Earth’s mantle, 400-600 kilometers (250-375 miles) beneath our feet.
The discovery seems to echo French science-fiction forerunner Jules Verne’s one hundred and fifty year old novel, ‘Journey to the Center of the Earth’, in which he depicted a vast sea that lay deep under our planet’s surface.
The evidence comes from a water-loving mineral called ringwoodite that came from the transition zone sandwiched between the upper and lower layers of the Earth’s mantle. Analysis shows that 1.5% of the rock comprises molecules of water.
The find backs the once thought theory that the transition zone, or at least significant parts of it, is rich in water. “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. Ringwoodite is named after Australian geologist Ted Ringwood, who theorized that a special mineral was bound to be created in the transition zone because of the ultra-high pressures and temperatures. A piece of this mineral has been a long-sought goal as it would resolve a long-running debate about where the poorly understood transition zone is dry, or rich in water. Until the recent discovery, ringwoodite has only ever been found in meteorites. Geologists have been unable to dig in deep enough to find any sample on Earth.
It all changed in 2008, when gem-hunters digging in shallow river gravel in Juina area of Mato Grasso, Brazil, came across a tiny grubby stone called a brown diamond. Measuring at just three millimeters(0.12 inches) across and commercially worthless, the stone was acquired by scientists when they were on a quest for other minerals.
The unintended possession turned out to be a stroke of luck. In its interior, they found a microscopic trace of ringwoodite – the very first terrestrial find of the ultra-rare rock.
“It was a bit of a piece of luck, this discovery, as are many scientific discoveries”. Pearson noted.
It’s theorized 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 specialized labs to confirm the find officially as ringwoodite.
Scientists have been debating for decades about whether the transition zone has water, and if so, how much of it might be there. However, Hans Keppler, a geologist at the University of Bayreuth in Germany, has cautioned against extrapolating the size of the subterranean water find from a single sample of ringwoodite. He also said the water was likely to be locked up in specific rocks, in a molecular form called hydroxyl.
The implications of the discovery are profound. If water exists in huge volumes beneath the 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.