Ancient Structures Hidden Beneath the Surface
Two giant, mysterious structures buried deep within Earth’s mantle may hold vital clues about how our planet formed and became capable of supporting life. The continent-sized “lava puddles” lie nearly 1,800 miles (2,900 kilometres) beneath the surface, resting above the boundary between the mantle and the core.
Researchers have long been puzzled by these vast formations, located beneath the Pacific Ocean and the African continent. Known as large low-shear-velocity provinces (LLSVPs) and ultra-low-velocity zones (ULVZs), they slow down seismic waves that pass through them — a sign that their composition differs from the surrounding mantle.
“These are not random oddities,” said Yoshinori Miyazaki, a geodynamicist at Rutgers University who led the research. “They are fingerprints of Earth’s earliest history. If we can understand why they exist, we can understand how our planet formed and why it became habitable.”
Remnants of Earth’s Magma Ocean
Billions of years ago, Earth was covered by a vast magma ocean. As it cooled, scientists believed the mantle should have settled into neat, uniform layers. Yet these two massive blobs suggest a more complex story.
Miyazaki and his team propose that the mysterious structures may be remnants of this “basal magma ocean.” Their model suggests that silicon and magnesium could have leaked from Earth’s core into the mantle during the planet’s early history, creating chemically distinct zones that cooled unevenly. These differences could explain why the blobs have persisted for billions of years.
Such interactions between the core and mantle may have influenced how Earth cooled, how volcanoes formed, and even how the planet’s early atmosphere developed — all critical factors that made life possible.
Unlocking Earth’s Earliest Secrets
Because scientists cannot directly explore the planet’s deep interior, they rely on seismic imaging to map the hidden landscape. By studying how earthquake waves slow down or speed up through different materials, researchers can infer what lies far beneath the crust.
“This work is a great example of how combining planetary science, geodynamics, and mineral physics can help us solve some of Earth’s oldest mysteries,” said Jie Deng, a co-author of the study and assistant professor of geosciences at Princeton University. “The idea that the deep mantle could still carry the chemical memory of early core-mantle interactions opens up new ways to understand Earth’s unique evolution.”
These findings not only deepen our understanding of Earth’s past but also offer clues to how other rocky planets might evolve — and what makes ours so uniquely suited to life.
with inputs from Space.com