Both, though plate tectonics are the ultimate limit. There's extraordinarily little primaeval crust extant on Earth. The Canadian Shield / Laurentine Plain is one of the largest, and is dated to 3.96 billion years, though the oldest is in Australia (Jack Hills region), with dates to 4.39 billion years via zircon crystals. (I believe that may geologically related to a region in southern Africa, with which it was originally joined, though cannot find a reference.)

The ocean floor is virtually completely newer material, little of it over a 200 million years old (about 5% of Earth's total age), due to subduction. Continental crust is lighter, floats on top of the heavier oceanic crust, and has at least a chance of survival.

https://www.thoughtco.com/how-old-is-the-ocean-floor-3960755

https://en.wikipedia.org/wiki/Canadian_Shield

https://en.wikipedia.org/wiki/Jack_Hills

https://www.geologyin.com/2015/11/44-billion-year-old-zircon...

https://www.geologyin.com/2016/03/the-oldest-mountain-on-ear...