Scientists at the Russian Institute of Geochemistry and Analytical Chemistry named after Vernadsky tried to find out how the layers of the Earth’s mantle, in which diamonds grow, arose.
Scientists conducted experiments at a pressure of 6 gigapascals, which is equivalent to a depth of 200 kilometers underground, where most of the diamonds were formed.
It is noteworthy that most of the diamonds were formed at a depth of 150-200 km at pressures of 5-7 GPa. At this pressure, diamond crystallization requires catalysts to help turn carbon into diamond. Synthetic diamonds are grown industrially by placing carbon in molten iron, nickel, cobalt or manganese.
In the 1990s, it was believed that diamonds also grow in nature by melting the metal. More recently, some crystals (at depths of more than 670 km) have been found to contain metallic inclusions. Meanwhile, most diamonds contain other inclusions, the composition of which varies from potassium aluminosilicate to alkali-carbonate and hydrochloric (chloride).
And the press service of the institute quotes an employee of the Laboratory of Chemistry of the Earth and the Earth’s Mantle, Dr. Anton Shatsky, said: “We came to the conclusion that the crystallization of most natural diamonds occurred as a result of melting, and its material was continental sediments, carbonates and sea salts that sank into the mantle Earth as a result of subduction of oceanic plates.
Scientists have previously shown that melts of aluminosilicate and potassium carbonate do not mix with each other (like oil and water), but are formed as a result of the partial dissolution of sediments that have descended from the continents from the oceanic plates into the oceans and oceans. Mantle of the Earth.
Sediments and melts formed as a result of heating and melting are enriched in varying degrees with sea salt (chlorides). In his study, Schatsky reported that scientists have experimentally shown that salt melts are low-temperature precursors or derivatives of carbonate solubility. Their experiments show that salt melts can be formed during the reduction melting of chlorine-containing carbonates with metallic iron. As a result, free carbon is released from the carbonate and diamond crystallizes.