Study Traces Plate Tectonics to 2.5 Billion Years Ago From 1,200 Rock Samples
Updated
Updated · The Conversation · Nov 11
Study Traces Plate Tectonics to 2.5 Billion Years Ago From 1,200 Rock Samples
3 articles · Updated · The Conversation · Nov 11
Summary
Chemical signatures in more than 1,200 rocks suggest Earth’s plate tectonics began about 2.5 billion years ago, marking a major shift in how the planet built continental crust.
Rocks older than 2.5 billion years repeatedly carry a fingerprint from crust formed roughly 4 billion years ago, but that signal disappears abruptly in younger rocks.
Researchers say the vanishing pattern points to a transition from remelting the same ancient crust to mixing recycled crust with fresh mantle material—the process seen today along plate boundaries.
The proposed turning point aligns with other changes from the same era, including shifts in rock chemistry, crust structure and the formation of Earth’s first supercontinent.
Because plate collisions and erosion erase much of the early geological record, the team says these preserved chemical traces offer a rare clue to when Earth’s tectonic engine switched on.