Scientists discover remnants of 4.5 billion-year-old proto-earth in the depths of earth

In a study recently published in the journal Nature Geoscience, scientists have identified ancient rocks deep inside the Earth's crust. They were chemical clues of this proto-Earth, the primordial planet that existed before the formation of the moon. This finding challenges the previous idea that an immense collision remelted and re-invented the Earth's chemical composition.

The study found clues in the ancient rocks from Greenland, Canada and Hawaii. The study poses immense potential, giving a window to look at the building blocks of primordial Earth and its neighbouring world.

"This is maybe the first direct evidence that we've preserved the proto-Earth materials," said Nicol Nile, an assistant professor of Earth and planetary sciences at MIT.

Scientists identified a rare chemical fingerprint, in the rock samples collected from Greenland, Canada, and Hawaii. These rocks have a certain kind of potassium imbalance, specifically, the potassium-40 isotope, when compared to most of the material found on Earth today. Potassium naturally occurs in three isotopes- potassium-39, potassium-40 and potassium-41, which are slightly different versions of the same element with different numbers of neutrons. Scientists use advanced mass spectrometry and trace the anomaly back to 4.5 million years ago.

4.5 billion years ago, the Earth was a giant hot, molten sphere of Lava formed from a swirling cloud of gas and dust. After 100 million years or so, a Mars-size asteroid collided with the Earth in an event so violent that it remelted and remixed the chemical composition of the Earth. The discovery challenges the existing theory of the reinvention of Earth following the great impact and suggests that some parts of the proto-Earth survived.

"We see a piece of the very ancient Earth, even before the giant impact," Nie said in the statement. "This is amazing because we would expect this very early signature to be slowly erased through Earth's evolution."

The chemical signature of proto-Earth material does not precisely match any known meteorite, necessarily implying that original materials that formed our planet may still be missing from geological collections.