The Earth’s surface is a collection of constantly moving tectonic plates, with new ones emerging as others are pulled down. This continuous cycle keeps our continents in motion and drives life on Earth.
A new study has discovered what happens when a plate disappears into the planet’s interior. Apparently the plates are significantly weakened as they sink but not so much that they break apart entirely.
The finding came after scientists put tectonic plates through a computer-generated model of destructive geological forces. The model showed that as the plate enters the mantle, it bends sharply downward, cracking its cold, brittle back. At the same time, the bending changes the fine grain structure of the rock on its underbelly, thus weakening it. The stresses pinch the plate along its weak points, leaving it mostly intact but segmented. The plate continues to be pulled under despite becoming folded and distorted.
When the researchers ran their simulations with a hotter interior, similar to the early Earth, the tectonic snake segments made it only a few miles into the mantle before breaking off. That means that subduction would have occurred intermittently, which raises the possibility that modern plate tectonics began only within the past billion years.