I am trying to understand how a dense basaltic lava is able to rise and punch through the continental crust, such as in mantle plumes or the Great East African Rift.
My understanding of plate tectonics is that continental crust is made from less dense silicates, where as oceanic crust is made from denser silicates.
The origin of continental crust is from the differentiation of Earth, where silicates rose to form the mantle and even lighter silicates rose, then cooled, to form the crust of early cratons.
If the mantle that forms oceanic crust is composed of dense silicates, how is it able to rise up and punch through the continental crust, pushing it apart to form ocean basins, as in areas of rifting or mantle plumes?
My intuition tells me a dense material should not be able to rise from depth and displace a lighter one.