What is the process called when oceanic crust sinks beneath a deep-ocean trench at a convergent boundary?

What is the process called when oceanic crust sinks beneath a deep-ocean trench at a convergent boundary?

• A. Subduction
• B. Seafloor Spreading
• C. Accretion
• D. Orogeny

Answer: (A)

Subduction is the process at a convergent boundary where oceanic crust sinks beneath another plate. Because oceanic crust is dense, it dives down into the mantle, creating a deep-ocean trench as it goes. This sinking drives earthquakes and melts the overlying mantle due to fluids released from the subducting slab, which can lead to volcanic activity on the overriding plate. This is different from seafloor spreading, where new crust forms as magma rises at mid-ocean ridges; accretion refers to material added to a continent or island, and orogeny is mountain-building from plate collisions.

Subduction is the process at a convergent boundary where oceanic crust sinks beneath another plate. Because oceanic crust is dense, it dives down into the mantle, creating a deep-ocean trench as it goes. This sinking drives earthquakes and melts the overlying mantle due to fluids released from the subducting slab, which can lead to volcanic activity on the overriding plate. This is different from seafloor spreading, where new crust forms as magma rises at mid-ocean ridges; accretion refers to material added to a continent or island, and orogeny is mountain-building from plate collisions.