WorldWide Drilling Resource

48 AUGUST 2014 WorldWide Drilling Resource ® U of A Makes Remarkable Discovery! Compiled by Bonnie Love, Editor WorldWide Drilling Resource ® One would not expect a $20 diamond to be a great discovery, but scientists were amazed with what the ugly, brown sliver of a diamond revealed. An international team of scientists led by Graham Pearson, Canada Excellence Research Chair inArctic Resources at the University of Alberta (U of A) analyzed the diamond and discovered the first sam- ple of the mineral ringwoodite to originate from earth. Ringwoodite is a form of the mineral peridot, also called olivine, and it has only been seen inmeteorites - until now. Pearson’s sample was found in 2008 in the Juina area of Mato Grosso, Brazil, where miners unearthed the host diamond which had been brought to the surface by a volcanic rock known as kimberlite - the most deeply derived of all volcanic rocks. Pearson said the discovery was al- most accidental; his team had been look- ing for another mineral to try and date the diamond. The ringwoodite itself is invisible to the naked eye, buried beneath the sur- face, so it was fortunate Pearson’s grad- uate student, John McNeill, found it. The sample underwent years of analy- sis using Raman and infrared spectroscopy and x-ray diffraction before it was official- ly confirmed as ringwoodite. Like diamonds, ringwoodite is formed under extreme pressure, and the only place on earth capable of such intense pressure is believed to exist in the transition zone located between the upper and lower mantle of earth. The composition of the transition zone has been debated amongst scientists; some believe it to be dry and desert like, and others believe it contains water. Although olivine only contains trace amounts of water, analysis of the ring- woodite revealed 1.5% of the sample’s weight was water. “This sample really pro- vides extremely strong confirmation that there are local wet spots deep in the earth in this area,” said Pearson. “That particular zone in the earth, the transition zone, might have as much water as all the world’s oceans put together.” Where does the water come from? Some believe the water was carried down by tectonic plates which were originally at the bottom of the ocean. Others theorize the water is comprised of hydrogen and oxygen atoms which were squeezed out of the surrounding rocks due to the incredible pressure. Will we ever be able to access the transition zone? So far, the deepest mine is just over 2 miles, and the deepest bore- hole is roughly 7 miles deep - we still have a long way to go. Currently, a group of international scientists are planning to drill into the upper mantle by 2020. For Pearson, one of the world’s lead- ing authorities in the study of deep earth diamond host rocks, the discovery ranks among the most significant of his career, confirming about 50 years of theoretical and experimental work by geophysicists, seismologists, and other scientists trying to understand the makeup of the earth’s interior. Photos courtesy of U of A.