What is the difference between the oceanic crust and continental crust and how does this influence plate boundary interactions?

Answer 1

When two plates move towards one another, they form either a subduction zone or a continental collision. This depends on the nature of the plates involved. In a subduction zone, the subducting plate, which is normally a plate with oceanic crust, moves beneath the other plate, which can be made of either oceanic or continental crust. During collisions between two continental plates, large mountain ranges, such as the Himalayas are formed.

Oceanic crust is a type of crust that is submerged in huge bodies of water, while continental crust is the type of crust beneath the continents.

Oceanic crust is thinner but denser, while the continental crust is thicker but lighter.

Whenever a continental crust and an oceanic crust meets and collides, they form a convergence zone. The oceanic crust sinks below the continental crust(subduction zone) because it is denser. As it sinks into the mantle, it becomes magma which soon rises up to the surface to stabilize the mantle, thus creating a volcano.

The continental crust, being the lighter one, does not sink. It may fold and form mountains.

The nature of a convergent boundary depends on the type of lithosphere in the plates that are colliding. Where a dense oceanic plate collides with a less-dense continental plate, the oceanic plate is typically thrust underneath because of the greater buoyancy of the continental lithosphere, forming a subduction zone. At the surface, the topographic expression is commonly an oceanic trench on the ocean side and a mountain range on the continental side. An example of a continental-oceanic subduction zone is the area along the western coast of South America where the oceanic Nazca Plate is being subducted beneath the continental South American Plate.