Large meteorite impacts drove plate-tectonic processes on the early Earth

An international study led by researchers at Macquarie University has uncovered the ways in which giant meteorite impacts may have helped to kick-start our planet’s global tectonic processes and magnetic field. The study, being published in the premier journal Nature Geoscience, explores the effect of meteorite bombardment, in geodynamic simulations of the early Earth.

To date, there is still not clear evidence to show whether plate tectonics operated in Earth’s early history, with the first 500 million years of our planet’s life, called the Hadean, often being dubbed as Earth’s geological dark ages. The little crust that has been preserved from this elusive period, mostly single grains of a mineral called zircon, has been used to argue for early tectonic activity. However, this is at odds with geochemical data and geodynamic simulations, which suggest that the Earth may instead have had a motionless ‘lid’ on its surface in contrast to the actively moving combination of plates we see today.

“We know that meteorite impacts had a huge effect on the inner solar system at this time,” says Associate Professor O’Neill, “you only need to look at the Moon to see that. What isn’t clear was how our own impact history might have affected the planet’s evolution.”

O’Neill also notes that while the magnetic field for much of Earth’s ancient history has been quite low, but recent work has suggested field strengths up to present-day values existed between around 4.0-4.1 billion years ago.

Overall, the study adds evidence towards the fact that meteorite impacts likely had a role in the formation of the Earth that we know today.