Scientists collected rock from the Isua Supracrustal belt, a region in southwest Greenland where exposed rocks are between 3.7 billion and 3.8 billion years old. The belt contains the oldest rock on Earth, which is relatively undisturbed by plate tectonics, heat and chemical changes, according to Science Magazine.
The chemical traces of the early magma oceans are even older than the rocks themselves, estimated to be about 4.5 billion years ago, when an object the size of Mars hit Earth, dropping a large chunk of rock that later became the Moon, according to the new study report.
“When celestial bodies the size of Earth and Mars collide, nearly large-scale melting of the entire planet is an inevitable consequence of that,” lead author Helen Williams, Professor of Geochemistry at the University of Cambridge, told Live Science.
And as the molten rock cooled and crystallized, the Earth gradually became like the blue marble we know today, he claims.
“But although most scientists accept the theory of Earth melting, the big challenge is that it is very difficult to find … geological evidence for something that happened early in our history,” Williams said.
The new study, published March 12 in the journal Science Advances, shows Isua belt rocks still have chemical “fingerprints” left by these ancient cooling processes.
Williams began looking for these “fingerprints” after he and co-author Hanika Rizo, a professor at Carleton University in Canada, met at the fall meeting of the American Geophysical Union (AGU), an annual event that in pre-pandemic times attracted tens of thousands of scientists. from all over the world.
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