2023-11-09 21:45:43
Recent research culminates a chain of discoveries that began in the 1980s, when geophysicists made an astonishing discovery: two enormous “lumps” were detected deep underground. One is under Africa and the other under the Pacific Ocean.
These clumps are technically called “large slow-speed provinces” because seismic waves travel through them more slowly than through other areas.
Each of these clumps is larger than the Moon, and research over the past decade has shown that they are most likely composed of different proportions of chemical elements than the surrounding mantle.
What is the origin of these two lumps?
It has long been unknown, but now a new study suggests that they are remains of an ancient planet that violently collided with Earth several billion years ago, in the same giant impact that caused the formation of our Moon.
The study was carried out by Qian Yuan’s team, formerly at Arizona State University (ASU) in the American city of Tempe and now at the California Institute of Technology (Caltech) in the United States.
For years, the idea has been accepted that in the remote past the Earth collided with another planet, smaller than it. It is also accepted that the Moon was created as a result of the colossal collision between the Earth and the aforementioned planet, which is called Theia and which was probably the size of Mars.
However, strangely, no trace of Theia has ever been discovered in the asteroid belt or in meteorites.
The new study explains the latter by suggesting that most of Theia was absorbed by the young Earth, forming the aforementioned gigantic clumps, while the residual remains of the impact coalesced into the Moon.
Artist’s recreation of Theia impacting the early Earth. (Illustration: Hernan Canellas / ASU)
The Moon appears to have within it materials representative of both the pre-impact Earth and Theia, but any remnants of Theia on Earth were thought to have been erased and homogenized by billions of years of dynamics (e.g., convection of the Moon). mantle) within the Earth, as argued by Steven Desch, a professor at Arizona State University and co-author of the new study. Now it seems clear that there are remains of Theia on Earth, and not exactly in small quantities.
This is the first study to defend the existence of “pieces” of Theia inside the Earth.
The study is titled “Moon-forming impactor as a source of Earth’s basal mantle anomalies.” And it has been published in the academic journal Nature. (Source: NCYT from Amazings)
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