Scientists have found a clue to the origin of the moon in Australian rocks

A new study by Australian geologists sheds light on the earliest history of our planet and indirectly on the process that led to the appearance of the moon. Scientists analyzed strontium and calcium isotopes in Archaean rocks more than 3 billion years old and found that the Earth's mantle began to lose its primary composition much later than the estimated time of the giant collision that gave rise to the satellite. This was reported on November 7 in the journal Nature.

The researchers analyzed the isotopic composition of the plagioclase mineral found in Archaean anorthosites and leucogabbro aged from 3.7 to 2.8 billion years. These rocks have preserved unique information about the early mantle of the Earth. The oldest sample was taken from a complex in Western Australia and demonstrated a record low ratio of strontium isotopes — the most pristine ever recorded on Earth.

Scientists have found that this ratio is close to the values found in lunar rocks, which indicates a common origin of the isotopic systems of the Earth and the Moon after a giant collision about 4.5 billion years ago. However, signs of a depleted mantle — that is, a mantle from which the crust has already partially formed — appeared only after a billion years. As the authors noted, this means that the active formation of the continental crust began relatively late — after 3.5 billion years ago.

According to geochemists, the discovered isotope ratios help clarify not only the time frame for the growth of the continents, but also the moment when the Earth and the Moon finally exchanged matter and isotopes after the collision. Based on the results of the analysis, scientists have proposed a refined model of the isotopic evolution of the Earth, which for the first time directly coordinates data on the mantle, continents and the origin of the Moon.

Top Signal: A new quasi-moon and a deadly rescue squirrel

Izvestia has prepared a selection of the most interesting science news for the week

Earlier, on October 27, BBC Science Focus magazine reported the discovery by astronomers of an unusual quasi-moon 2025 PN7, which accompanies the Earth in motion through outer space. It was clarified that the object does not revolve around the planet directly, but only is nearby and follows it on its way around the Sun.

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