The process of oceanic crust being subducted under continental crust is primarily due to differences in density and composition between the two types of crust.
Oceanic crust is generally denser and thinner than continental crust. It is primarily composed of basaltic rock, which is heavier than the granitic rocks that make up the continental crust. As tectonic plates interact, the denser oceanic plate tends to sink beneath the lighter continental plate in a process known as subduction.
This subduction occurs at convergent plate boundaries where the two plates collide. The oceanic crust is forced downward into the mantle, a layer of the Earth beneath the crust. As the oceanic plate descends, it can create features such as deep ocean trenches and volcanic arcs along the edges of the continental plate.
Additionally, the movement of tectonic plates and the resulting subduction can lead to significant geological events, including earthquakes and volcanic eruptions, making this process vital to understanding Earth’s geology and tectonic activity.