Suppose plate subduction. At about 2.3 cm per year. Slow and gradual.
Now imagine two freight trains on the same tracks in a hard rock cut with open air on the top . Rock on three sides.
Moving at the same 2.3 cm speed.
One is loaded with basalt. The other Granite.
Which train is going to dive underground. into the Subduction zone?
How does a small rock, ocean crust, brittle slide under a bigger rock. When the path of least resistance is simply to pile up.
The basalt train would pile up. As its mass is not as strong.
"How does a small rock, ocean crust, brittle slide under a bigger rock. When the path of least resistance is simply to pile up. "
This doesn't make any sense.
Imagine if I have two apples and I put them into a bowl of water. And let's say that one apple is slightly more dense than the other.
Part of each apple rises above the surface of the water.
If I run the apples into one another, one apple attempts to rise into the air, while the more dense apple sinks.
In the real world, oceanic lithosphere is chemically altered during subduction, resulting in an increased density, which essentially pulls oceanic lithosphere into the mantle.
It would be akin to the Apple that sinks, slightly increasing to a density greater than water and being pulled down in.
So, while the Apple that rises into the air can rise some amount, ultimately, the denser apple goes underwater, thus removing further displacement of the lighter apple into the air.
The lighter apple isn't going to go up into the air because the denser apple is predominantly sinking under water.
Just the same, the continental lithosphere isn't going up into the atmosphere because your oceanic lithosphere is being pulled into the mantle.
There is also the driving force behind the subducting lithosphere, which continues to push, further driving subduction along with the increasing densities pull.