Fate of Sinking Tectonic Plates

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In summary, scientists have found that sinking tectonic plates do not break apart entirely, but are weakened significantly. This reconciles the two stories that conventional wisdom said needed to remain intact - that sinking plates must pull on the portion behind it.
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What happens when a plate disappears into the planet’s interior?
Just stumbled across this and thought it was interesting.


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

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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.

Screen Shot 2021-12-15 at 9.36.27 AM.png

There could well be a variety of forces acting on plates in different ways.
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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.
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1. What causes tectonic plates to sink?

Tectonic plates sink due to the process of subduction, where one plate is forced underneath another plate due to differences in density. This can occur when an oceanic plate collides with a continental plate, or when two oceanic plates collide.

2. How does the sinking of tectonic plates affect the Earth's surface?

The sinking of tectonic plates can result in the formation of mountain ranges, deep ocean trenches, and volcanic activity. It also plays a critical role in the movement of continents and the creation of new land masses.

3. Can tectonic plates resurface after sinking?

Yes, tectonic plates can resurface through the process of uplift, where the sinking plate is pushed back towards the Earth's surface. This can occur due to changes in the Earth's mantle or the collision of tectonic plates.

4. What happens to the oceanic crust when a tectonic plate sinks?

When an oceanic plate sinks, the oceanic crust is also subducted and eventually melts into the Earth's mantle. This process recycles old oceanic crust and creates new oceanic crust at mid-ocean ridges.

5. How does the fate of sinking tectonic plates impact the Earth's climate?

The sinking of tectonic plates can affect the Earth's climate through the release of carbon dioxide and other gases from volcanic activity. These gases can contribute to the greenhouse effect and impact global temperatures. Additionally, the movement of tectonic plates can also impact ocean currents and weather patterns.

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