Modern-style plate tectonics is running
Rock dragged 70 kilometres down and back up proves subduction worked the way it does today.
- When
- Known to
- ± 20 million years
- Era
- Neoarchean, Archean
Eclogite-facies rocks in a 2.52-billion-year-old ophiolitic mélange in the North China Craton record oceanic crust subducted to depths of 65 to 70 kilometres and returned to the surface. That combination of high pressure and relatively low temperature only occurs in cold, steep subduction — the modern regime. It pushes firm evidence for modern-style plate tectonics back 400 million years, to the close of the Archean.