While experimenting with a laser "anvil" press in the German DESY Synchrotron Center the Russian and German physics and geologists have found an earlier unknown layer in the Earth's mantle, which contains a huge amount of liquid oxygen.

This was reported in their article in the Nature Communications magazine.

"By our estimates this layer contains approximately 8-10 times more oxygen, than the Earth atmosphere does. It was a great surprise to us, and we don't know yet what happens to these "oxygen rivers" in the planet interior" — the Russian scientist Elena Bykova from the Bayreuth University (Germany) pointed out.

Elena Bykova and her colleagues have discovered an unexpected source and accumulation of oxygen in the Earth interior, while observing the condition of various types of ferrous oxide, which is one of the main components of abyssal rocks, when subjected to various temperatures and pressures.

As scientists explain, in normal conditions ferrous oxide in terrestral rocks is represented with hematite – an aggregation of two iron atoms and three oxygen atoms. In recent years, according to Elena Bykova, chemists and physicists have discovered several new "versions" of ferrous oxide, which are formed under high pressures and temperatures and comprise exotic numbers of atoms, such as Fe4O5, Fe5O6, or Fe13O19, for instance.

The authors of the article found out that the list of ferrous oxides is not limited to it. They checked the behaviour of gematite and magnetite, Fe3O4, under conditions close to those in the Earth core and mantle, having pressured  them with the laser "anvil" PETRA III. That pressure exceeded atmospheric pressure 670 thousand times.

This action led to decomposition of hematite and generation of a new exotic ferrous oxide, Fe5O7, under the pressure and temperatures like those at the depth of 1500 kilometers. Further compression resulted in generation of another unknown ferrous oxide, Fe25O32. Both cases brought about the emission of massive volume of oxygen, which turns into liquid instead of gas under such pressure and at such depth.

Streams of this oxygen liquid, according to Elena Bykova and her colleagues, often flow through the Earth mantle in those areas where the deposits of magnetite and hematite generated at the bottom of the sea "flow" together with other matter of the mantle and crust the core of the Earth.

The destiny of this oxygen remains unknown – these oxygen "rivers" can both interact with surrounding rocks and oxidize them, and rise to the higher layers of the mantle and even above it.

Anyway, the presence of oxygen shows that most complicated and active chemical processes may be taking place in the Earth interior, though we do not know them yet. These processes may influence not only geochemistry, but also the climate and the atmosphere of the Earth, as Maxim Bykov, another author of the article emphasized.