A Chemical Fingerprint in Ancient Rocks Suggests Plate Tectonics Began 2.5 Billion Years Ago

Ancient rocks hold clues to the origins of Earth's plate tectonics, which could explain why our planet is so different from its neighbors. Plate tectonics helps regulate Earth's climate, magnetic field, and supports long-term habitability for complex life. However, the exact timeline of when this process began has been unclear. A new study analyzed chemical fingerprints in over 1,000 rocks and found evidence suggesting plate tectonics began around 2.5 billion years ago.

This marks a significant change in how Earth builds its continents, as the fingerprints of very ancient crust, which existed around four billion years ago, were no longer present in the younger rocks studied. The findings suggest that before 2.5 billion years ago, the same ancient continental material was repeatedly melted and remelted to create new crust, but after this point, the planet started producing crust from a mix of old and new sources.

This shift coincided with other major changes on Earth, such as alterations in rock chemistry, crust thickness, and composition, as well as the formation of Earth's first supercontinent. While the exact trigger for the beginning of plate tectonics remains unknown, this study provides valuable insight into when and how this fundamental geological process began.