2 upvotes, 1 direct replies (showing 1)
View submission: Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science
I suppose this kind of begs another question though — why do we have this binary "crust density" grouping? Could you not get a portion of crust or tectonic plate which is somewhere in between the two, and behaves accordingly differently to both?
Comment by I_likeIceSheets at 20/07/2022 at 21:23 UTC
4 upvotes, 1 direct replies
It's not binary, just oceanic crust tends to be denser than continental crust. Oceans are deep so the magma from the mantle below goes through less silica-rich crust, so when new rock is formed it's pretty mafic and dense. On the continents, magma goes through thicker silica-rich crust, so when new rock is formed, it tends to be felsic and buoyant.
But there are also places on the continents (think of places like Nevada) where the crust is thin and new rock formed in basins are mafic or intermediate.