Published on March 13th, 20130
Researchers have discovered the origin of diamonds
In recent years, Jacques and his colleagues have gathered evidence suggesting that elcogitic diamonds have entered the terrestrial mantle in the form of organic matter from tectonic plate movements, a process called subduction. There, the organic matter was subjected to extreme temperatures and pressure, and thus it was transformed into diamonds.
Most of the diamonds, including those found in the famous Australian Argyle mine seem to have an organic origin situated on the seafloor.
Most diamonds can be classified into two types, depending on which rocks are formed: elcogitic and peridotitic. However, the origin of elcogitic diamonds was unknown.
“Isotopic ratio of these diamonds is very different from terrestrial mantle composition. They are different than what you’d expect to find in the mantle“, said Lynton Jaques, coauthor of the new study.
One explanation could be that high temperatures cause crystallization of mantle diamonds from carbon-rich fluids. “But we, like many others, I felt that this is not the complete answer”.
In their last theory, researchers have examined the composition of mineral inclusions in diamonds oxygen obtained from Western Australia, Venezuela and Botswana. Thus, scientists have found a correlation unnoticed until now. Virtually all diamonds had a few carbon isotopes of silicate inclusions and there were unusually high proportions of isotopes of oxygen.
Diamonds composition was appropriate to what you’d expect to find in the seabed.
“The only way I can explain it is by subduction of organic carbon as the source for carbon in diamonds“, concluded the expert.
Sursa: ABC Science