(ORDO NEWS) — Microscopic inclusions inside the diamond told the story of its origin. The crystal was formed at a depth of more than 600 kilometers, in the transitional layer of the mantle, and in the presence of a sufficient amount of water.
Even the deepest man-made wells do not penetrate far enough into the earth’s interior. We can learn about what is happening hundreds of kilometers below by the minerals that are carried out from there closer to the surface.
Not so long ago, a similar sample (weighing one and a half carats) was found in diamond mines in Botswana, after which it fell into the hands of geologists.
Scientists have found that a diamond with numerous mineral inclusions was formed at a depth of about 660 kilometers, and even there the molten rocks contain a considerable amount of water.
In total, the geologists examined 12 microscopic inclusions in the sample, studying them using X-ray and Raman spectroscopy.
This made it possible to find mantle minerals such as ringwoodite, ferropericlase, and enstatite in them. Under certain conditions, including high pressure, ringwoodite is able to transform into ferropericlase and bridgmanite, and under lower pressure bridgmanite becomes enstatite.
Thus, the combination of all three minerals told a lot about the circumstances of the formation of diamond and the appearance of inclusions in it.
As a result, geologists determined that the sample comes from a depth of 660 kilometers. This is an extremely interesting area separating the lower and upper mantles, where a rather rapid change in its composition, density and other properties takes place.
And the presence of ringwoodite, brucite and some other minerals in the recently studied sample indicates the presence of water even at such a great depth. Evidence of this was known before, but, judging by the new data, there should be a lot of water in the transitional layer of the mantle.
Recall that although the surface of the Earth is covered by almost three-quarters of the oceans, no less moisture is hidden deeper.
Through cracks in the lithosphere, water seeps down and enters the mantle. After some time, it can again rise to the top: for example, with emissions from volcanoes.
This long geological cycle of water plays a large role in the processes covering the planet as a whole. The new work will allow you to better understand how it works.
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