Science Olympiad Dynamic Planet Practice Test

During oceanic-oceanic convergence, what happens to the older and denser oceanic plate?

1. It rises to form new crust

2. It sinks into the mantle

3. It melts into a new ocean

4. It transforms into continental lithosphere

The correct answer is: It sinks into the mantle

During oceanic-oceanic convergence, the tectonic plates collide in a way that the older and denser oceanic plate is subducted into the mantle. This process occurs because, as oceanic plates age, they become cooler and denser. The denser plate is forced beneath the less dense plate, creating a subduction zone. As the subducted plate descends into the mantle, it can lead to various geological phenomena, including the formation of deep ocean trenches and volcanic arcs. The sinking plate can also release water and other materials back into the mantle, contributing to magma formation and leading to volcanic activity in the overriding plate. This interaction highlights the dynamic nature of oceanic plates and their role in shaping the Earth’s geology.