However I stumbled upon a research article that cites "Most exposed continental crust that can be dated back to the Archaean eon (4 billion to 2.5 billion years ago) comprises of..." as summary of another article.
So there is a fraction of crust that survives this process and is several cycles old. Do we know the fraction of material in the crust that survived this process?
在这个“超大陆周期”中幸存下来的部分非常小,只能在少数几个露头的地方找到....一般是加拿大、格陵兰岛等地的内部克拉通的一部分。然而,即使在这些太古宙盾状岩石中,“原始地壳”的体积本身也非常小,很难找到,并且在化学方面存在争议。原始的地壳物质可以追溯到前构造(冥古宙)时期,它必须是由熔融物质冷却形成的,并且本身包含一种非常具体的化学特征,这是理论上的,但尚不确定。< / p >
Given how small that volume is, and how difficult it is to access many of these rocks, it's unlikely that anyone will pony up the money for a deep seismological survey of their extent at depth, so, a solid number for volume will not be forthcoming soon.
Basically oceanic crust is guaranteed to be reworked eventually, check the age of oceanic crust, while continental crust has a more random factor involved meaning some in the more stable regions of some continents has not been reworked. That is why they are only small scattered areas.