Recently, the research group Wen Lianxing, a professor of earth and earth interior physics laboratory at the University of Science and Technology of China, used seismic observation data to find that there is a pasty layer in the local area at the boundary of the inner core of the Earth for the first time. Relevant results August 1 online published in "Nature - Communications."
The Earth's solid core is gradually solidified from the liquid outer core as the Earth's cooling. As the Earth's core continuously releases latent heat and throws light matter during its growth, it provides the driving force for the thermo-chemical convection of the liquid outer core and the "geomagnetic generator", thus forming the Earth's magnetic field. Therefore, knowing the solidification state of the Earth's core is the key to understanding the physical mechanism of the origin of the Earth's magnetic field. Since the 1980s, scientists have predicted that there may be three regions near the boundary of the Earth's core: the upper region (ie, the extragalactic core) in purely liquid form, the lower region (ie, the earth's core) in purely solid form, Liquid coexistence exists in the middle of the area (ie paste layer). Although the presence of the mushy layer at the boundary of the Earth's core is of crucial significance in understanding the solidification process of the Earth's core, no observation has been found in the scientific community.
By analyzing the trend and waveform of the seismic waves reflected from the Hippocampus Hi-net at the core of the Earth's core, researchers found that there is a thickness of about 4 to 8 km at the core of the Earth's core below the southwestern Sea of ​​Okhotsk Of the mushy layer, while the boundaries of the other Earth's cores adjacent to this area show a sharp interface and no mushy layer exists.
The results of this study provide direct evidence for the existence of the paste boundary layer at the core boundary and also show that the paste layer exists only in the local area of ​​the Earth's core. The results show that the driving force of geomagnetic field changes with the region and the composition of the Earth's outer core is close to that of the eutectic composition of iron and light elements, thus forming a sharp kernel interface without smear layer in most areas. In some areas, The extraterrestrial core deviates from the eutectic composition of iron and light elements and forms a local mushy layer.