Metamorphism is a sub solidus process. what it means by sub solidus?

sub solidus means any point lie below the solidus line in phase diagram. Subsolidus represent that the material is in solid state..... Metamorphism is a process in which compositi...

solid state diffusion happens in metamorphism when a substance is undergone a stage where it's neither completely solid it has some property of fluid which helps in exchange of ion...