A new study reveals surprising clues to the start of subduction on earth

Subduction, a crucial geological process on earth, may have started hundreds of millions of years earlier than traditionally raw.

This surprising discovery comes from a new study published by researchers from the GFZ Helmholtz Center for Geosciences, as well as international colleagues, in Nature communications. The Potsdam (Germany), Grenoble (France) and Madison (USA) team presents revolutionary evidence that the subduction and the formation of continental crusts during the so-called Eon Hadean were already active and more vigorous than we thought before.

The Eon Hadean, extending from 4.6 to 4.0 billion years, remains the most enigmatic chapter in the history of the earth. He started with the formation of the planet, followed by a massive collision with a body the size of a March which led to the creation of the Moon and the complete fusion of the interior of the earth. The solidification of the crust of the earth began about 4.5 billion years ago, but what happened afterwards was long debated.

The dominant theory suggests that up to at least the end of the Hadéan, the earth was locked in a tectonic regime of the “stagnant” lid. In this model, our planet was covered by a rigid and motionless external shell, with convection processes occurring below in the mantle of the earth-by putting the subduction, that is to say the sinking down of the crust in the interior of the earth and the formation of continental crusts seen in the modern tectonics of the plates.

Now the researchers question this point of view.

In their new study, the team presents evidence that the subduction and formation of continental crusts were already active and more vigorous in the Hadean than we thought before. Using an innovative analytical technique, the Grenoble team has measured the isotopes of strontium and trace elements in fusion inclusions preserved in olivine crystals of 3.3 billion olivine. Meanwhile, the GFZ team used advanced geodynamic simulations to interpret these geochemical signals in terms of early land.

Their combined results suggest much more active early land, indicating that in -depth subduction and continent formation may have started hundreds of millions of years earlier than before.