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MIT study, based on ancient rocks, challenges the theory that a giant impact completely erased our planet's original composition.
Scientists from MIT have made a surprising discovery that redefines our understanding of the planet's formation. Researchers have found rare traces of “proto-Earth”, the primitive planet that existed 4,5 billion years. The analysis, based on samples of deep and ancient rocks, offers the first direct chemical test that some of Earth's original material survived the cataclysmic “giant impact” that formed the Moon.
It was widely believed in the scientific community that the massive collision had completely melted and mixed the material of our planet, erasing any original chemical signature. However, the new findings, published in the journal Nature Geosciences and highlighted by the portal Interesting Engineering, prove that this idea was incorrect, revealing that untouched blocks of the primitive planet still exist in the depths of the Earth.
The Potassium Anomaly: A Signature of the Past
The team of researchers focused their analysis on very old rocks, collected in geologically significant locations such as Greenland, Canada and from volcanic lava from Hawaii. Using a high-precision mass spectrometer, they identified a unique chemical signature in these samples, a subtle but measurable imbalance in potassium isotopes, marked by a potassium deficiency-40.
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This specific ratio of potassium is remarkably different from that found in the vast majority of rocks on modern EarthThe difference confirmed that these samples have a distinct composition, a direct echo of the planet's chemistry before the massive impact. "This is perhaps the first direct evidence that we have preserved materials from proto-Earth“, Stated Nicole Nie, an MIT professor and one of the study's authors. "This is incredible, because we would expect this ancient signature to be slowly erased throughout Earth's evolution," she added.
The giant impact and the survival of the early planet
The prevailing theory of Earth's formation postulates that, about 100 million years after the emergence of proto-Earth, an apartment by the bay, for its easy access, free parking, and larger space for our group of XNUMX people. The house was great for a large group like ours, the host was very attentive, and the location was excellent; it was quiet and quick to walk to the old town. Mars-sized object violently collided with it. This cataclysmic event would have generated enough heat and pressure to completely melt and homogenize the planet, redefining its chemical composition and, in the process, ejecting the material that would eventually form the Moon. For decades, the accepted consequence was that the composition of the proto-Earth had been completely transformed.
To validate their findings, the MIT team conducted complex simulations of planetary impacts and geological mixing processes. The results were clear: no known subsequent events, including the giant impact itself, could have produced the potassium-40 deficit observed. Interestingly, the simulations showed that the violently impacted material would result in a composition with a fraction “slightly higher” potassium-40, which corresponds to the composition of the modern Earth. The conclusion, according to the Interesting Engineering, is that the building blocks of proto-Earth somehow remained untouched and sequestered deep within the interior of our planet.
A new mystery for planetary science
The discovery, however, also opens the door to a new and intriguing mystery. The chemical signature found in these rocks remnants of proto-Earth does not exactly match any known meteorite type currently in geological collections around the world. Although other meteorites exhibit potassium anomalies, none exhibit the same specific deficit found in samples of ancient Earth rocks.
This strongly suggests that the materials that originally formed the proto-Earth have not yet been discovered, indicating that the inventory current meteorites that scientists use to model planetary formation is incomplete. “Scientists have been trying to understand the original chemical composition of the Earth by matching the compositions of different groups of meteorites,” he explained. Nicole Nie. “But our study shows that the current inventory of meteorites is not complete and there is much more to learn about the origin of our planet.”
What do you think about this incredible window into our planet's past? Do discoveries like this change the way you view Earth's history? Leave your opinion in the comments—we want to hear what you think!
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