Science & Technology, Canada (Commonwealth Union) – The word diamond comes from the Greek word “adamas, which means indestructible, as they are one of the hardest components. The value diamonds are linked to its rare nature and its splendid appearance; however, a new study reveals that the value of diamonds may go beyond its splendor.
A unique combination of minerals deep within a “superdeep” diamond that originated hundreds of kilometer’s underneath the Earth’s surface provides new insights to plate tectonics, the geological processes leading to mountains, oceans and continents.
One of the inclusions observed in the diamond was with that of the mineral olivine, a magnesium iron silicate, that is a significant rock forming mineral. Majority of the olivine on Earth contains components of iron in it, so the purity of this olivine demonstrates the unique nature under which it was produced, according to researchers.
The olivine’s purity, together with some of the other minerals included in this diamond, demonstrate a far deeper origin than is normal for a diamond, between what is known as the transition zone and the lower mantle zone, which is 420 kilometers to 660 kilometers below the surface of the Earth. It also indicates that the environment between these zones has a highly variable oxygen level.
“To make this extreme composition [of olivine] and the overall mineral assemblage that we’ve got, the only way of doing that is to have a very deeply subducted oceanic plate or slab that goes down into the mantle, so you’re essentially pushing material from the surface of the Earth into the depths of the Earth,” said University of Alberta’s study co-author Graham Pearson, professor in the Department of Earth and Atmospheric Sciences and director of the Diamond Exploration and Research Training School.
He further said “You get huge gradients in oxygen activity when you do that, and these big gradients are very conducive to driving extreme variations in composition of minerals.”
Obtaining knowledge of these oxygen gradients can assist our understanding on the way plate tectonics brings volatile components back up into the mantle, and may further give clues to the way superdeep diamonds are produced, where we are unable to gain knowledge such as this in any other way, according to Professor Pearson.
“You can see oceanic slabs descending into the Earth in seismic images, but you don’t have any idea of the detailed structures they develop, or the mechanisms and chemistry going on in those slabs,” he says. “These diamonds provide a unique trace of that detailed chemical evolution as the slab’s going down.
Plate tectonics is linked in the forming of many things from mountains to oceans to continents, and even has an impact on the Earth’s climate. The furthering of knowledge of plate tectonics may also assist us to better understand natural events such as earthquakes and volcanic eruptions, according to Professor Pearson.
Superdeep diamonds, which originate from depths of over 300 kilometer’s underneath the Earth’s surface, are a priced possession of information for scientists as diamonds are uniquely capable of preserving information linked to where they are produced, including much of the physical and chemical procedures that happened when they were formed.
A majority of the other minerals discard many of that information as they make their way to Earth’s surface, however as Professor Pearson explains, diamonds act in a similar manner to time capsules.
“There are many things at the surface of the Earth that can only be explained by processes happening at deep depths,” says Professor Pearson further adding that the need of explaining things visible at the surface, be it economic mineralization, surface uplift or subsidence phenomena related to oil-bearing basins, will require a knowledge of the structure, mechanics and properties from the deep Earth. Diamond is uniquely able to enhance that knowledge.
The study is likely to be a valuable source of information for a variety of scientists from many different fields.
