Caltech Links 2 Deep Mantle Blobs to Theia in 4.5-Billion-Year Moon-Forming Impact
Updated
Updated · The Brighter Side of News · Aug 15
Caltech Links 2 Deep Mantle Blobs to Theia in 4.5-Billion-Year Moon-Forming Impact
3 articles · Updated · The Brighter Side of News · Aug 15
Summary
Two continent-sized structures near Earth’s core may be remnants of Theia, a Caltech-led Nature study says, offering a possible first physical trace of the body thought to have helped form the Moon 4.5 billion years ago.
Simulations found iron-rich Theia material could have survived the collision, stayed 2% to 3.5% denser than Earth’s mantle, and sunk to the core-mantle boundary instead of fully mixing.
Over 4.5 billion years, that material formed two thermochemical piles resembling today’s LLVPs, with modeled shear-wave speeds 1% to 5% slower than surrounding mantle and a footprint close to the roughly 4% observed.
The authors say the case is not conclusive because LLVPs may also include ancient subducted crust, but chemical and isotopic tests comparing plume-fed volcanic rocks with lunar samples could verify the Theia link.
If confirmed, the finding would suggest giant impacts can leave long-lived chemical structures inside rocky planets, reshaping models of Earth’s early mantle, plate tectonics and even other worlds’ interiors.
Could the mysterious continent-sized blobs deep inside Earth actually be the graveyard of an alien world that created our Moon?
Will the latest lunar soil samples finally prove that Earth swallowed an ancient planet 4.5 billion years ago?
Theia’s Hidden Legacy: How Deep Mantle Blobs Reveal Earth’s Violent Origins and Shape Our Planet Today
Overview
About 4.5 billion years ago, the protoplanet Theia collided with the young Earth, blasting debris that formed the Moon. However, a significant portion of Theia’s dense, iron-rich mantle was absorbed into Earth. Because the lower mantle stayed cool, this material did not fully mix and instead, over billions of years, sank to the core-mantle boundary. There, it accumulated into two giant structures called Large Low-Velocity Provinces (LLVPs), which slow seismic waves due to their high iron content. These deep-mantle blobs influence volcanic hotspots, plate tectonics, and even the stability of Earth’s magnetic field today.