Earth's chemistry settled early but later collision likely delivered water for life

Earth's chemistry settled early but later collision likely delivered water for life
by Clarence Oxford
Los Angeles CA (SPX) Sep 01, 2025

Earths chemical make-up reached completion within the first three million years of the Solar Systems formation, according to a new study by the University of Berns Institute of Geological Sciences. However, this early Earth, known as the proto-Earth, lacked volatile elements such as water and carbon compounds that are essential for life.

The findings, published in Science Advances, suggest that a later planetary collision was critical for supplying these life-supporting materials. The research points to a massive impact with Theia, a planetary body thought to have formed further out in the Solar System where water and other volatiles were abundant.

"Our Solar System formed around 4,568 million years ago. Considering that it only took up to 3 million years to determine the chemical properties of the Earth, this is surprisingly fast," said lead author Dr. Pascal Kruttasch, who completed the work during his dissertation at Bern and is now an SNSF Postdoc.Mobility Fellow at Imperial College London.

The team combined isotope and elemental data from meteorites and terrestrial rocks with model calculations to reconstruct Earths formation. They used manganese-53 radioactive decay to chromium-53 as a high-precision chronometer, offering dating accuracy of less than a million years.

"These measurements were only possible because the University of Bern has internationally recognized expertise and infrastructure for the analysis of extraterrestrial materials and is a leader in the field of isotope geochemistry," said co-author Klaus Mezger, Professor Emeritus of Geochemistry at the University of Bern.

The study concludes that without the Theia impact, the proto-Earth would have remained a dry, rocky planet. "Thanks to our results, we know that the proto-Earth was initially a dry rocky planet. It can therefore be assumed that it was only the collision with Theia that brought volatile elements to Earth and ultimately made life possible there," Kruttasch explained.

Mezger emphasized that this underscores the rare circumstances behind Earths habitability. "The Earth does not owe its current life-friendliness to a continuous development, but probably to a chance event - the late impact of a foreign, water-rich body. This makes it clear that life-friendliness in the universe is anything but a matter of course," he said.

The researchers now aim to model the collision between proto-Earth and Theia more precisely, to explain both the physical and chemical features of the Earth-Moon system.

Research Report:Time of proto-Earth reservoir formation and volatile element depletion from 53Mn-53Cr chronometry