Diamonds are valuable due to their scarcity. One day this may change if the results of the new study can ever be harvested. The research has found that one to two percent of Earth’s oldest mantle rocks are formed from diamond. For the time being, however, a diamond rush is unlikely. The diamonds are buried more than 100 miles below the surface, which is considerably deeper than any drilling expedition has ever managed. The study was undertaken by the Massachusetts Institute of Technology.
The focus of the research was on cratonic roots, which can stretch as deep as 200 miles through the Earth’s crust and into the mantle. Cratons are generally found in the interiors of tectonic plates. Before the revelation about diamonds, cratons were are thought to be composed of ancient crystalline basement rock, some of which is covered by younger sedimentary rock.
As well as being used to scan for earthquakes, scientists use seismic receivers to help build up a picture of what the Earth’s interior looks like. This happens because the speed that sound moves at varies according to the type of material and the temperature of that material. From such measurements, scientists construct a model of the types of rocks that make up the Earth’s crust. The presence of diamonds was found because a set of sound waves sped up significantly as they passed through the roots of ancient cratons. The sound velocity in diamond is more than twice as fast as the other minerals.
According to lead researcher Ulrich Faul: “This shows that diamond is not perhaps this exotic mineral, but on the geological scale of things, it’s relatively common.”
The research has been published in the journal Geochemistry, Geophysics, Geosystems, with the research paper titled “Multidisciplinary Constraints on the Abundance of Diamond and Eclogite in the Cratonic Lithosphere.”
