Analysis of 3.3 billion-year-old olivine crystals suggests Earth's Hadean Eon featured intense subduction and early continent formation. This challenges the long-held stagnant lid hypothesis for the planet's infancy. Researchers combined geochemistry and geodynamic models to uncover this dynamic past.
The Hadean Eon, spanning from 4.6 to 4.0 billion years ago, began with Earth's formation and a massive collision that formed the Moon, leaving the interior molten. A solid crust emerged around 4.5 billion years ago, but the nature of subsequent tectonic activity has been debated. Traditionally, scientists envisioned a stagnant lid regime, where a rigid outer shell prevented subduction—the sinking of crust into the mantle—and delayed continental crust development until later eons.
A new study from the ERC Synergy Grant Project Monitoring Earth Evolution through Time (MEET) upends this view. Geochemists from Grenoble, France, and Madison, USA, examined strontium isotopes and trace elements in melt inclusions within 3.3-billion-year-old olivine crystals. These inclusions act as preserved snapshots of ancient magmas. Meanwhile, geodynamic modelers at the GFZ Helmholtz Centre for Geosciences in Potsdam, Germany, simulated how these geochemical signatures align with tectonic processes.
The results, published in Nature Communications, indicate that subduction was active and possibly more vigorous than in modern times during the Hadean. Continental crust growth likely started several hundred million years earlier than previously thought, pointing to a highly dynamic early Earth with widespread crust recycling and mantle convection driving surface changes.
This evidence comes from the journal article by Adrien Vezinet and colleagues, based on materials from GFZ Helmholtz-Zentrum für Geoforschung. The findings highlight how ancient minerals and computational models can rewrite our understanding of planetary evolution, emphasizing an active rather than quiescent start for Earth.