Dr Graham Pearson, Canada Excellence Research Chair on Arctic Resources, in the Department of Earth & Atmospheric Sciences at the University of Alberta answers this and other related questions.
The water that has been discovered inside a diamond and was brought to the surface thanks to a volcano; that was written about recently in nature and science magazines, is water that is locked in a crystalline lattice, at a depth of over 600 kilometres down. All Jules Verne fans may be thinking that this is proof that there are seas down there. But free moving water at those depths is impossible Dr Pearson says, because of pressure. The water has been become a part of solid material, which has been brought to the surface through on-going movement in the earth’s mantle.
The implications of this discovery highlights a potential explanation for intra-plate volcanoes that form well away from the subduction zones where we have island arcs which form a ‘ring of fire’ around the pacific, Dr Pearson explains.
Dr Pearson says that underground water at such depths is very important in understanding how the volatility of the earth works. There is a huge amount of water trapped in rock and sediment which can be released and which can drive volcanoes. One of the reason why the earth has tectonic plates is because water weakens rocks, especially rocks which are heated to 700 degrees. This is one of the things that lubricates the plate tectonic process, Dr Pearson explains. So this is all part of a picture that we building up to understand where water is formed, how it is stored and how it moves from great depths to the surface.
Do we know how the water got down here in the first place?, host John Harrison asks.
Dr Pearson says that much of the water seems to have been produced from the effect of the cosmic cocktail that occurred as a result of the collision of meteorites. Some of the water may be primordial water trapped 4.5 million years ago. However, because of the process of movement, the supply of water that is trapped deep in the earth would probably have been emptied twice over during the earth’s history, so there must be process of putting water back into the earth going on, from the earth’s oceans. But the replacement cycle is very long for anybody thinking that this may be a way a sort of get out of jail card, to solve the problem of anthropological pollution of the seas.
In reply to the question: should we be looking more closely at our own planet instead of spending trillions of dollars on space exploration, Dr Pearson says than spending money on science is certainly better value for money than giving rich people tax breaks, or spending a lot of money on wars, but you need to do both because the sort of research we are talking about; into underground water, provides a fairly limited snapshot of what happened in the earth’s history. Going to another planet which has a history of moving tectonic plates provides us with a much clearer vision of what happened than studying the earth. The other thing about going to other planets is that it does tend to drive new technology, he said. So you need to do both.
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