GEOLOGY

Detailed explanation-1: -In particular, ocean trenches are a feature of convergent plate boundaries, where two or more tectonic plates meet. At many convergent plate boundaries, dense lithosphere melts or slides beneath less-dense lithosphere in a process called subduction, creating a trench.

Detailed explanation-2: -As with oceanic-continental convergence, when two oceanic plates converge, one is usually subducted under the other, and in the process a trench is formed. The Marianas Trench (paralleling the Mariana Islands), for example, marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate.

Detailed explanation-3: -Oceanic-Oceanic Convergent Boundary An oceanic-oceanic convergent boundary describes a collision between two plates composed of oceanic lithosphere. Even though this boundary involves the same type of lithosphere, one of the plates will still subduct beneath the other.

Detailed explanation-4: -Examples of ocean-ocean convergent zones are subduction of the Pacific Plate south of Alaska (creating the Aleutian Islands) and under the Philippine Plate, where it creates the Marianas Trench, the deepest part of the ocean.

Detailed explanation-5: -Divergent plate boundaries in the ocean create mid-ocean ridges. This is where new seafloor is created by upwelling magma. Divergent plate boundaries rift a continent apart. Eventually a new ocean will form between the two continents.