What do you think of when you think of the Earth’s core? Bubbling molten lava? Solid rock? Do you think it’s hollow? Recent studies have shown that close to the Earth’s core there is potentially water and lots of it. The water is hidden inside a blue rock called Ringwoodite that lies up to 700 km underground in the mantle, the layer of hot rock between Earth’s surface and its core. Almost sounds too bizarre to be true but this is causing scientists to really ponder the origins of the Earth’s water.
There has been a long held debate as to where the water on Earth originated. One theory is that it came from Comets but Comets are richer in deuterium, a stable heavy isotope of Hydrogen, and Earth’s oceans only have 1 atom of deuterium for every 6420 of free Hydrogen. Comets or asteroids striking the earth should have also brought more platinum and other rare elements than have been found. This is where the evidence that the Earth’s oceans may actually have sprung up from within and possibly not from extraterrestrial sources.
Steve Jacobsen, Associate Professor from the Department of Earth and Planetary Sciences is a mineralogist specializing in the field of Mineral Physics. He and his team believe there is a hidden, much larger geochemical reservoir underneath the Earth’s surface that provides the oceans with continual supply. This water is contained inside Ringwoodite, a rock that is formed at high pressure and temperatures and amazingly, can hold hydroxide (oxygen and hydrogen atoms bound together) within its structure. “It’s rock with water along the boundaries between the grains, almost as if they’re sweating,” says Jacobsen.
Jocobsen and his team were literally “pinging the planet” after earthquakes to test how certain areas of the earth’s core reacted to seismic waves. By measuring the speed of the waves at different depths, the water layer revealed itself because the waves slowed down as it takes them longer to get through moist rock than dry rock. Jacobsen did several laboratory studies on Ringwoodite by pressurizing and heating it like it would be treated in the ‘Transition zone’ (between 410 to 660 km below you). Its reaction in the lab led Jacobsen to infer that there could indeed be vast amounts of water trapped below the earth’s surface inside the rock.
Graham Pearson of the University of Alberta holds a similar belief. He has a piece of Ringwoodite that exploded from a volcano that was found almost by accident – hiding in the form of a diamond. Analysis of the mineral shows it contains a significant amount of water, in fact, 1.5 per cent of its weight. What is interesting is that this is the only terrestrial piece of Ringwoodite ever found.
While debate goes on surrounding the topic it is interesting to think of how little we actually do know about the origins of water on this blue planet of ours. Perhaps idea that it was birthed from inside the planet and not as a result of meteorite debris opens up a whole other realm of discoveries to be had.
– C.Reynolds
