A new vision of these anomalies was published in the journal Nature Geoscience. Moreover, according to one of the authors, geodynamicist Yoshinori Miyazaki from Rutgers University, it may indicate their key role in ensuring our planet’s ability to support life. Extraordinary Formations in the Earth’s Interior Low Shear Velocity Provinces (LLSVP) and Ultra-Low Velocity Zones (ULVZ) are located at the boundary between the planet’s mantle and core, at a depth of about 2900 kilometers. LLSVPs are enormous accumulations of dense, heated material the size of an entire continent; one such formation is under Africa, another under the Pacific Ocean. ULVZs are thin, molten patches “stuck” to the core, resembling lava spills. Both of these structures significantly slow down the passage of seismic waves, which indicates their atypical composition. “These are not just random fluctuations. They are imprints from the earliest stage of Earth’s history. By deciphering the reason for their formation, we can understand how our planet was formed and what contributed to its habitability,” Miyazaki is convinced. Solving the Mystery of the Earth’s Mantle The researcher explains that billions of years ago, the Earth was entirely a global magma ocean. Scientists had assumed that as this ocean cooled, it should have formed clearly defined chemical layers, much like concentrated and watery fractions separate when juice freezes. However, seismic data do not reveal such distinct stratification. On the contrary, LLSVPs and ULVZs appear as a disordered aggregation right at the base of the planet. “This discrepancy was the starting point,” Miyazaki explains. “If we follow the magma ocean model and conduct the corresponding calculations, we do not get the configuration we observe in the mantle now. Something was missing.” His colleagues concluded that this missing component is the core itself. According to their model, over billions of years, elements such as silicon and magnesium migrated from the core into the mantle, reacting with it and preventing the formation of strict chemical separation. These additions can explain the anomalous composition of the structures, which can now be interpreted as frozen remnants of the so-called “basal magma ocean,” “contaminated” with material from the core. “We hypothesized that the source could be material seeping from the core. Incorporating this core component helps explain the picture we observe,” comments the geodynamicist. Significance for Life Support and Earth’s Evolution Processes This discovery is important not only for understanding deep chemical processes, Miyazaki emphasizes. The interaction between the core and the mantle could have influenced the cooling rate of the planet, the nature of volcanic activity, and even the formation of the atmosphere. This might be the key to understanding why Earth has oceans and life, while Venus has turned into a scorching greenhouse and Mars has become an icy desert. “Earth has water, life, and a relatively stable atmosphere,” Miyazaki recalls. “Venus’s atmosphere is a hundred times denser than Earth’s and consists mainly of carbon dioxide, while the Martian atmosphere is extremely thin. We still don’t fully understand the reasons for these differences. However, the processes occurring inside the planet—how it cools, how its layers evolve—may be an important part of the answer.” By combining seismic data, information on mineral physics, and geodynamic modeling, this study presents LLSVPs and ULVZs as key clues in understanding the processes of Earth’s formation. These structures may even feed mantle plumes (for example, under Hawaii and Iceland), thereby connecting the planet’s deep interior with its surface. “This work is a great illustration of how the synergy of planetary science, geodynamics, and mineral physics helps us solve Earth’s oldest mysteries. The idea that the deep mantle may still hold the chemical trace of early core-mantle interactions opens new horizons for understanding our planet’s unique evolution,” believes Jie Deng from Princeton University, a co-author of the study. Each new confirmation helps fill the gaps in Earth’s early history, assembling fragmented observations into a more coherent picture of its development. “Even with a limited number of clues, we are beginning to build a logical narrative. This research gives us more confidence in understanding how the Earth has evolved and what lies at the root of its exceptional nature,” Miyazaki concluded.
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