Fate of Sinking Tectonic Plates

[Tom.G]

TL;DR Summary

What happens when a plate disappears into the planet’s interior?

Just stumbled across this and thought it was interesting.

https://scitechdaily.com/fate-of-si...uzzled-scientists-now-theyve-found-an-answer/

But what happens when a plate disappears into the planet’s interior?
The question has long puzzled scientists because conventional wisdom said that sinking tectonic plates must remain intact to keep pulling on the portion behind it, but according to geophysical evidence, they are destroyed.Now, in a study published recently in Nature, scientists say they’ve found an answer that reconciles the two stories: Plates are significantly weakened as they sink but not so much that they break apart entirely.

The original is behind a paywall at: https://doi.org/10.1038/s41586-021-03937-x

Cheers,
Tom

 

[BillTre]

Pulling of subducting plates is the most common explanation I have heard for tectonic plate movement, however ...

I have also read somewhere (don't remember where) that another force driving the movement of tectonic plates is a pushing force from mid-ocean ridges. They are higher in elevation than surrounding areas and gravity pulls them away from the ridge and therefore pushes the oceanic crust outward toward its subduction region.

Additionally, I don't think that all tectonic plates are associated with a subduction zone (for example in the western Atlantic). So if they are moving, there should be some other reason for it.

Here is a recent article (behind Science paywall) that describes two kinds of subduction zones with fast and slow sinking subducting plates. The difference seems due to the relative temperature of plates and their surroundings. This results in a density difference and therefore drive different rates of sinking.

There could well be a variety of forces acting on plates in different ways.

 

[Astronuc]

A related thread - https://www.physicsforums.com/threads/future-of-tectonic-plates.1009325/A nice video discussing early phase in Earth history - before plate tectonics. At 2:16 in the video, an animation shows convection in the mantle. Subducting plates push down and melt, then the rock flows elsewhere.