Chinese researchers have discovered remarkable zones deep within the Earth, approximately 2,900 kilometers below, near the core-mantle boundary, acting as a massive natural barrier hindering heat transfer.
These zones, known as “Ultra-Low Velocity Zones (ULVZs),” are relatively small, not exceeding a few hundred kilometers in diameter. They intrigue geophysicists due to their remarkably low seismic velocity and high density.
Scientists from the “Chinese Academy of Sciences” and “National Taiwan University” studied the impact of these zones on Earth’s thermal balance. The researchers used “ultrafast transient absorption spectroscopy with diamond anvil cells” to generate extremely high levels of pressure and heat. They then measured the thermal conductivity of the primary component of these zones, “iron-rich magnesiowüstite.” The results surprisingly showed that this material has a very low thermal conductivity, much lower than the surrounding rocks in the mantle.
The models explained that the distinctive properties of “ULVZs” – “low velocity, high temperature, and high density” – make them resemble localized “thermal blankets.” They significantly slow down the transfer of heat from the hot core to the mantle, altering the spatial distribution of heat flux and potentially leading to the formation of localized thermal layers at the top of the core.
According to what was published in the journal “Nature Communications,” this discovery has fundamental implications, as heat exchange in the core-mantle boundary directly affects thermal convection in the liquid outer core, which is responsible for generating Earth’s magnetic field (the geodynamo). The thermal insulation properties of these zones may affect the stability of the magnetic field, its polarity, and its long-term evolution, which protects life on Earth from cosmic radiation.
Scientists emphasize that this discovery is just the beginning of a deeper understanding of the complex internal structure of the Earth, noting the need for further research to obtain a complete picture.
