Hidden Depths: Uncovering Theia’s Mysterious Remnants Inside Earth

New research suggests that large remnants of Theia, a MarsMars is the second smallest planet in our solar system and the fourth planet from the sun. It is a dusty, cold, desert world with a very thin atmosphere. Iron oxide is prevalent in Mars' surface resulting in its reddish color and its nickname "The Red Planet." Mars' name comes from the Roman god of war.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Mars-sized object that collided with Earth to form the Moon, still exist within Earth’s mantle. These remnants are thought to be linked to seismic anomalies and could provide insights into Earth’s geological history and plate tectonic patterns.

Scientists have dated the birth of the Solar System to about 4.57 billion years ago. About 60 million years later a “giant impact” collision between the infant Earth and a Mars-sized body called Theia created the Moon.

Now, new research published in Nature suggests that the remains of the large object that collided with the young Earth to form the Moon are still identifiable deep within the planet as two large lumps. These lumps make up about 8% of the volume of the Earth’s mantle, which is the rocky zone between the Earth’s iron core and its crust.

The new study, led by Qian Yuan of Arizona State University and Caltech, argues that the heat generated by this collision was not enough to melt the whole of the Earth’s mantle, so the innermost mantle remained solid.

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A high resolution computer simulation of Theia colliding with the Earth to form the Moon.

Consequently, the researchers say, the melted mantle of Theia didn’t completely mix with Earth’s mantle. That would have made the Theia remnants indistinguishable from Earth’s mantle as a whole. Instead, a lot of Theia’s mantle ended up as two continent-sized lumps that now sit on top of the Earth’s core-mantle boundary.

Large Low-Velocity Provinces

Yuan argues that these lumps correspond to, and can explain, the existence of the two large low-velocity provinces (LLVPs), that were discovered decades ago: one below the Pacific and another below Africa and the eastern Atlantic.

This discovery was thanks to the observation that the vibrations emanating from earthquakes, known as seismic waves, travel through these regions slightly more slowly than through “normal” lower mantle.

Source: SciTechDaily