Look at a Diamond & You May See an Ocean

University of Alberta Professor Graham Pearson studies the relationship between diamonds & deep earth water cycles.

 |  Transcript [PDF]

When you think about a journey to the deep Earth, you probably picture tunnelling through soil, then maybe hitting some rocks, before getting to the molten magma core of the Earth. It may seem pretty dry, but add it all together and there are vast oceans’ worth of water trapped 450-600 km underground. Graham Pearson, Canada Excellence Research Chair in Arctic Resources at the University of Alberta, made this discovery by using diamonds as tiny indestructible capsules from the deep Earth.

Diamonds that are not gem quality contain inclusions: pockets of impurities that contain materials from the deep Earth where they formed, providing a unique snapshot of an area that is too deep for us to observe directly.

Studying water from diamonds allows Prof. Pearson to estimate that the transition zone where diamonds form is about 1% water, adding up to several oceans’ worth of water trapped at that depth. This information is critical to understanding how water cycles, helping us make better use of our natural resources without damaging the environment. This is particularly important in the Arctic, which has huge untapped resources, but is also a very fragile ecosystem.

Understanding how water cycles through the deep Earth is important to understanding the whole system of water on Earth.

“If it’s raining outside today, that water ultimately came from the deepest parts of the Earth,” explains Pearson. “Most water on Earth came to the Earth from the form of meteorites and comets, and it gets trapped in the deepest parts of the Earth and it gets cycled around out of volcanoes, into the atmosphere. It goes into the ocean and then that part of the cycle is then a bit of a mystery and we’re trying to fill in the picture.

“The inclusions in diamonds tell us that somehow ocean water – very large fractions of ocean water – get cycled down into the deep Earth. They stay there for hundreds of millions of years and then that water ends up coming up again in volcanoes and ends up back in the atmosphere. So the rain that is falling today might be in and out of the deepest parts of the Earth two or three times.”

Now that you know about how we get water from diamonds, come to the blog to find out how we get diamonds from water.

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D. Graham Pearson is one of the world’s leading scientists in diamond studies and understanding the formation of diamond-forming roots beneath continents. He is at the forefront of developing new techniques for geochemical analysis, and has pioneered new methods of dating minute geological samples.

His development of the first technique to determine when an individual diamond was created won him the prestigious Lindgren Medal of the Society of Economic Geologists in 1999. He also developed the first quantitative fingerprinting technology that can determine the geographical origin of a diamond, which has implications for markets that rely on the export and sale of “conflict diamonds”.

Before assuming his position as Canada Excellence Research Chair in Arctic Resources at the University of Alberta, Pearson was professor of geochemistry at Durham University in the United Kingdom. He holds a PhD in earth sciences from Leeds University, and has a bachelor’s degree in geology from the Imperial College of Science and Technology. After his graduate studies, he served as research fellow at Carnegie University in Washington, D.C., and the Open University in Milton Keynes, UK.