Igneous Rocks and Plate Boundaries. Intense igneous activity happens along divergent and some convergent plate boundaries. Divergent plate boundaries are where plates move away from each other. These create rift valleys (on the continents) and mid-ocean ridges (in the oceans).

What are the most important types of rock in the crust?

• Granite is great stuff! Not only is it my personal favorite, it is without a doubt the most common rock type on the continental land masses.
• Basalt is extrusive.
• As it turns out, most of the ocean floor is basalt, and most of the continents are granite.

Continental crust is mostly composed of different types of granites. Geologists often refer to the rocks of the continental crust as “sial.” Sial stands for silicate and aluminum, the most abundant minerals in continental crust.

Divergent plate boundaries

They float on top of the hot, deep layers of the earth where magma is found. The plates can either get closer together or drift apart, and this tectonic plate movement gives us the right conditions for the formation of igneous rocks, which are rocks that form from the cooling and solidifying of magma.

pumice

Because of the dominance of oxygen and silicon in the crust, igneous rocks are mostly made up of silicate minerals. These silicates can be generally divided into light and dark silicates. The dark silicates are also called ferromagnesian because of the presence of iron and magnesium in them.