Two massive structures located at the boundary between Earth’s mantle and core may hold clues to the origins of life on our planet. A recent study published in the journal Nature Geoscience by a team led by Yoshinori Miyazaki, a geodynamicist at Rutgers University, proposes a new theory regarding these enigmatic formations, which have perplexed scientists for decades.
These continent-sized masses of dense, hot rock lie nearly 1,800 miles beneath the Earth’s surface, beneath regions such as Africa and the Pacific Ocean. They have been detected through seismic wave readings, revealing significant variations in the surrounding rock composition. “These are not random oddities,” stated Miyazaki. “They are fingerprints of Earth’s earliest history.”
Understanding these structures could illuminate how our planet formed and evolved into a habitat capable of supporting life. Current theories suggest that early Earth developed a mantle billions of years ago from a vast magma ocean, which differentiated into concentrated and less concentrated material over time. This process has been likened to “frozen juice separating into sugary concentrate and watery ice.” Yet, evidence supporting this theory has been elusive.
Instead of uniform layers, researchers have identified irregular formations known as “large-low shear velocity provinces” and “ultra-low velocity zones,” which are characterized by significantly slowed seismic waves. “That contradiction was the starting point,” Miyazaki explained. The findings suggest that our understanding of the mantle’s development is incomplete, as calculations based on the magma ocean concept do not align with current observations.
In their research, Miyazaki and his colleagues modeled conditions from billions of years ago. They proposed that a slow leak of silicon and magnesium from the Earth’s core could have contaminated the basal magma ocean. This contamination may have prevented complete solidification in certain areas, resulting in the uneven structure observed today. “If you add the core component, it could explain what we see right now,” Miyazaki noted.
This mechanism might have also contributed to the Earth’s cooling, leading to volcanic activity and shaping the development of the planet’s atmosphere. The findings could help explain why Earth is unique in its ability to sustain life, contrasting sharply with other planets such as Venus and Mars. “Earth has water, life, and a relatively stable atmosphere,” Miyazaki articulated. In comparison, Venus has a much thicker atmosphere composed primarily of carbon dioxide, while Mars possesses a thin atmosphere that is largely inhospitable.
While this theory is still in its early stages, it offers promising insights into the evolutionary history of our planet. “What happens inside a planet, how it cools, and how its layers evolve could be a big part of the answer,” Miyazaki concluded, despite acknowledging that researchers still have “very few clues.”
As scientific exploration continues, the implications of these findings may deepen our understanding of Earth’s origins and its exceptional status in the universe.
