Find out even the approximate composition is very difficult to. He was evaluated on the basis of geochemistry and research-based history of the formation of planets in the Solar System. Scientists know that the liquid core is composed mainly of iron- nickel alloy, but it is believed that small amounts of some other elements are also present in the nucleus.
Oxygen - is the most widely distributed element on the planet, so it is logical to assume that oxygen might be one of the dominant ... But a new study team Inveya Fay of Washington Geophysical Laboratory, Carnegie shows that evidence of the presence of oxygen in the outer core is not. This fact is of great importance for our understanding of the period when the Earth was formed through the accretion of cosmic dust and material.
Today's technology can allow to obtain samples of materials from another planet, but, surprisingly, find the kernel is still impossible to directly. To investigate the Earth's core by using seismic sensing equipment detects the reflected waves, the scientists can deduce the approximate composition of the substance through which these waves.
According to current models, except for a large amount of ferrous materials, liquid outer core of the Earth contains a small percentage of the so-called light elements - possibly, sulfur, silicon, carbon or hydrogen, and the minimum amount of oxygen. This study leads Fay, in cooperation with Chinese counterparts, including the lead author of the study Hayyuna Huang Wuhan University of Technology in China, which currently works at the Carnegie. A team from the study of new experimental data that narrow the identity of the light elements present in the outer core of the Earth.
The deeper the dive under the earth's surface, the greater the increase and the pressure and temperature. As a result, the materials begin to work and interact differently from how they behave on the surface. In the center of the Earth's liquid outer core are solid and the inner core. Scientists believe that the light elements play an important role in the convection of the liquid outer core that generates Earth's magnetic field.
Scientists know the changes in the functions of the density and sound velocity as a function of the depth of the core of the seismic observations, but until now it was difficult to measure these properties in a proposed iron- nickel alloys in the nucleus, taking into account the pressure and temperature in the laboratory on the surface of the Earth.
... Thus, we need to simulate all the conditions and learn about the properties of the material in the nucleus by means of high-tech laboratory experiments, combining modeling and seismic data, ...
High exposure can produce a shock wave (shock wave ), which will trigger increased pressure and temperature materials, both leading to melting of the material at a pressure similar to that in the outer core. The team conducted experiments with a shock wave with the use of basic materials, whose presence is assumed in the core - a mixture of iron, sulfur and oxygen. Scientists have brought the material to a liquid state and measured the density and velocity of sound passing through them, under conditions that simulate conditions in the liquid core.
Comparing the data with the observations, the researchers concluded that oxygen can not be the main light element, the material constituting the outer core, because the experiments were conducted on oxygen-rich materials do not converge with the geophysical observations. This proves the validity of recent models of the early Earth, which has evolved little in the oxidized environment.
... Further research should focus on the synthesizing of these elements, the next step will be based on the elucidation of the potential content of elements such as silicon, in the outer core ...
These studies are supported by the National Natural Science Foundation of China, the Foundation for fundamental research universities, the National Science Foundation and the Carnegie Science Institute.
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