Geologists from Lomonosov Moscow State University, together with colleagues from Switzerland and Australia, conducted a large-scale experiment, which, according to them, made it possible to unravel the mystery of the origin of mantle keels - the ancient diamond-bearing "roots" of the continents.

The discovery is reported in the journal Nature.

An international team of scientists has combined the power of three supercomputers to reconstruct the processes that took place in the earth's mantle during the earliest (Precambrian) period of the geological history of our planet. 

“We used three supercomputers for our experiments: our Lomonosov supercomputer at Moscow State University and two supercomputers at the Swiss Higher Technical School of Zurich.

We have created a computer model that reproduces the features of the ancient (Archean) oceanic crust and mantle, ”said the head of the team, head of the Department of Petrology and Volcanology of the Geological Faculty of Moscow State University, Professor Alexei Leonidovich Perchuk.

According to the calculations of the scientist and his colleagues, in ancient times the process of subduction (immersion of the earth's crust into the bowels of the planet) was different from the modern one.

“The ancient subduction involved the upper mantle of a different chemical composition, which was primarily devoid of an iron component and therefore very light.

Because of this, it did not go entirely into the depths, but flowed in giant "tongues" under the continent, where it subsequently froze, "explained Professor Perchuk.

Scientists have found that in this way a stable layered structure, different from the rest of the mantle, was formed under the continent, which cooled and solidified over several billion years.

Geologists call the resulting unusual formations mantle keels or "roots" of the continents.

Their age ranges from 1.5 to 3.5 billion years, and they go into the Earth to a depth of 350 km.

Such "roots" have a special geochemical composition, and it is in them that most of the planet's diamonds are located.

The hypothesis of the origin of diamondiferous mantle keels is indirectly confirmed by earlier independent studies of scientists.

According to Professor Perchuk, at the beginning of this century, a colleague of Russian geologists, Professor Griffin from Macquarie University in Australia, studied the composition of the deep mantle from xenoliths (alien inclusions in igneous rock) in kimberlite pipes.

The results of his research showed that this mantle contains areas with anomalous chemical composition at a depth of 150-200 km.

  • Earth in the Precambrian geological period.

    At this time, the diamondiferous "roots" of the continents were formed

  • Gettyimages.ru

  • © allou

The research team paid special attention to the process of diamond formation in these structures.

According to their calculations, while the light and hot part of the oceanic mantle flowed under the continent, the colder and more saturated with water minerals part of the oceanic mantle, together with the oceanic crust, sank to greater depths.

As a result, carbon-containing aqueous fluids were released, which rose upward and saturated the mantle keels with carbon, which led to the appearance of the hardest minerals on Earth - diamonds.