Modeling has shown that during previous geological eras in the mantle, part of which was still liquid, intensive convective flows. In conjunction with previous studies, indicating the high conductivity of silicate melts at high pressure, this suggests that the ancient Earth’s magnetic field could answer her gown. This is at odds with the prevailing notion that only flows of liquid metal in the core produce Earth’s magnetic field and earth-like planets. Article published in the journal Earth and Planetary Science Letters.
The interior of the Earth consists of three layers: metallic core, solid stone mantle and thin crust. The kernel, in turn, is divided into a solid inner and liquid outer, and that flows resulting from heat exchange of the solid and liquid parts produce a magnetic field.
The problem is that the solid inner core was formed not earlier than 1.5 billion years ago, while recent studies showthat the magnetic field existed for 4.2 billion years ago. It’s called a New paradox of the kernel, which previously tried to explain to the scientist from Japan.
Research Nicholas Blank (Blanc Nicolas A.) from the Institute of Geophysics and physics of planets summarizes a number of recently published ideas and with the help of simulation confirms the possibility of generating magnetic fields at the core and mantle. For a long time scientists did not consider this possibility, because he assumed that mantle froze almost immediately after the formation of the Earth, and only in 2007, French researchers suggestedthat the lower third of the mantle has long been a basalt ocean.
But there were other obstacles to the adoption of the theory of basalt of the Dynamo. To run the fluid must be conductive, but in normal conditions of silicic rocks practically do not conduct electricity. In the laboratory to reproduce extreme temperature and pressure of the earth’s interior is impossible, so in 2017 scientists using quantum devices have calculated the electrical conductivity of the silica, and it was enough for Dynamo-effect.
Finally, for generating the magnetic field flows must be very powerful, why the need for an intensive heat exchange. Crystallization and melting are effective ways to transfer heat. Because of this melting ice cube cools a drink stronger than stone or iron, lying in the same freezer. Inside the earth’s basaltic ocean kristallizuetsya the basalt, transferring its heat from the center outward. For a quantitative study of this process, the group of Nicolas Blanca built thermo-chemical-dynamical model of the earth’s interior. According to their calculations, the heat flux capacity of a few tens of terawatts through the mantle really was able to start convection currents of molten rock, and consequently create a magnetic field.
The depths of the Earth is inaccessible to direct observation, and in their study had to rely on indirect methods, first and foremost, on the propagation of sound waves. By studying them, scientists were able to detect underground mountains and to measure the rate of growth of the nucleus.