How much time is needed for plate tectonics to subdue everything?

[Marco Masi]

I read of fossile records as old as 3.8 billion years. How can this be? Since I thought that it takes about 500 mio. years for plate tectonics to force all the Earth crust into the subduction zones into the mantle. No evidence should be left. I'm confused...

 

[Bystander]

You really think tectonic activity is 100% efficient?

 

[davenn]

I read of fossile records as old as 3.8 billion years. How can this be? Since I thought that it takes about 500 mio. years for plate tectonics to force all the Earth crust into the subduction zones into the mantle. No evidence should be left. I'm confused...

you are coming from a mistaken understanding.
~ 95% of subduction is oceanic crust NOT continental crust

There are very few places around the world where continental crust is being subducted or anything similar to that. One of those places is the Indian sub-continent as it pushes into the Euro-Asian continent.
There is a mixture of subduction and just straight out collision.Dave

 

[BillTre]

Here is a recent little note about the oldest known piece of oceanic crust:
http://www.sciencemag.org/news/2016/08/mediterranean-sea-may-harbor-piece-oldest-ocean-crust
It is about 340 MY old.

 

[DrDu]

Even if the mean turnover time were of the order of 500 Ma, this is to a large extent a statistical process. I.e. there is lot of material which is subduced earlier and some material which is not subduced at all.