New research led by Caltech proposes that two gigantic iron-rich blobs found deep in Earth’s mantle are remnants of the ancient planet Theia, which collided with Earth billions of years ago and led to the formation of the Moon.
Mysterious Structures Discovered Within Earth’s Interior
In the 1980s, scientists discovered two massive continent-sized structures nestled near Earth’s core using seismic wave measurements.
Dubbed large low-velocity provinces (LLVPs), these giant blobs have unusually high iron content compared to the surrounding mantle material. One sits beneath Africa and the other below the Pacific.
The strange structures measure twice the size of the Moon, leaving scientists puzzled about their origins and composition.
Linking LLVPs to Theia Impact That Formed Moon
The new study suggests the LLVPs are remnants of Theia, an ancient Mars-sized planet that violently struck the early Earth, resulting in debris coalescing into the Moon.
The findings provide a long-sought answer regarding the fate of Theia, which had vanished without a trace. The research ties together the genesis of the Moon and the mystery LLVP structures.
Simulating Theia’s Collision With Early Earth
Led by geophysicist Qian Yuan of Caltech, the research team conducted simulations modeling the hypothetical giant impact between Theia and Earth 4.5 billion years ago.
The simulations paint a scenario where most of Theia’s iron-rich mantle gets absorbed into Earth after the collision, eventually concentrating into the distinct LLVP structures detected today.
Leftover debris from the impact formed the Moon, explaining its high iron composition.
Ancient Blobs Stayed Intact Despite Violent Impact
Surprisingly, the chunks of Theia’s mantle remained largely intact instead of thoroughly mixing with Earth’s own mantle.
The team’s models showed the lower mantle retained enough heat from the impact to keep Theia’s iron-rich material solid and clumped together as it sank, like wax in a lava lamp.
This allowed the material to settle neatly into two separate blobs rather than dispersing evenly.
New Insights Into Earth and Moon’s Dramatic Origins
By linking the mysterious LLVPs and Moon to the same ancient impact, the study untangles key questions around Earth and the Moon’s formative history.
The violent collision with Theia profoundly shaped our planet’s ensuing evolution and development.
Researchers next aim to study how these ancient buried remnants from Theia influenced early processes like tectonic shifts and mineral formation.
The giant impact theory continues gaining credibility as evidence builds a coherent narrative about the Moon and Earth’s intertwined origins.