Diamond clue to vast 'oceans' beneath the earth
Posted on Mar 13 2014 | IANS
Toronto, March 13 : In a ground-breaking discovery, researchers have found a gem that points towards the existence of vast 'oceans' beneath the earth.
A diamond scientist from University of Alberta has found the first terrestrial sample of a water-rich gem that yields new evidence about the existence of large volumes of water deep below the surface.
Analysis of the mineral shows it contains a significant amount of water - 1.5 percent of its weight - a finding that confirms scientific theories about vast volumes of water trapped 410 to 660 km 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 Graham Pearson, Canada Excellence Research Chair in arctic resources at University of Alberta.
That particular zone in the Earth, the transition zone, might have as much water as all the world's oceans put together.
Ringwoodite is a form of the mineral peridot - believed to exist in large quantities under high pressures in the transition zone.
Ringwoodite has been found in meteorites but, until now, no terrestrial sample has ever been unearthed because scientists have not been able to conduct fieldwork at extreme depths.
This sample was found in the Juina area of Mato Grosso, Brazil, where artisan miners unearthed the host diamond from shallow river gravels.
The diamond had been brought to the earth's surface by a volcanic rock known as kimberlite- the most deeply derived of all volcanic rocks.
For Pearson, the discovery confirms about 50 years of theoretical and experimental work by geophysicists, seismologists and other scientists trying to understand the makeup of the earth's interior.
Knowing water exists beneath the crust has implications for the study of volcanism and plate tectonics, affecting how rock melts, cools and shifts below the crust, said the study published in the journal Nature.