A continent – continent convergent plate boundary does not have a subduction zone. Explain!
The correct answer and explanation is :
A continent-continent convergent plate boundary does not have a subduction zone because both continents have similar densities and buoyancies, making it difficult for one to be forced beneath the other. Let me break this down further.
At convergent boundaries, tectonic plates move toward each other, and typically, one plate is forced beneath the other in a process known as subduction. This occurs when a dense, oceanic plate meets a less dense, continental plate. The denser oceanic plate is subducted, or forced downward, into the mantle, leading to the formation of deep ocean trenches and volcanic activity.
However, in the case of continent-continent convergence, the situation is different. Both plates are primarily composed of continental crust, which is relatively buoyant and light compared to oceanic crust. When two continental plates collide, neither is dense enough to sink into the mantle. As a result, the plates buckle, fold, and crumple at the boundary. This creates mountain ranges rather than subduction zones. The Himalayas (formed by the collision of the Indian Plate and the Eurasian Plate) are a prime example of this type of boundary interaction.
Additionally, the thickness and rigidity of continental crust make it more resistant to subduction. As the plates push against each other, the crust is instead pushed upward, forming mountain chains, or it can be subjected to intense compression and thrust faulting.
Because there is no subduction of one plate beneath the other, volcanic activity is generally absent at continent-continent boundaries, in contrast to subduction zones, where volcanoes are common due to the melting of subducted material.
In conclusion, the lack of a subduction zone at continent-continent convergent boundaries is due to the similar buoyancy and composition of the plates involved, which causes the crust to compress and uplift rather than subduct.