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Caroline plate – Minor oceanic tectonic plate north of New Guinea – 1,700,000 km 2 (660,000 sq mi) Cocos plate – Young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America – 2,900,000 km 2 (1,100,000 sq mi) Indian plate – Minor plate that separated from Gondwana – 11,900,000 km 2 (4,600,000 sq mi)
Oceanic crust is formed at sea-floor spreading centers. Continental crust is formed through arc volcanism and accretion of terranes through plate tectonic processes. Oceanic crust is denser than continental crust because it has less silicon and more of the heavier elements than continental crust.
Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction. [citation needed]
Some lithospheric plates consist of both continental and oceanic lithosphere. In some instances, initial convergence with another plate will destroy oceanic lithosphere, leading to convergence of two continental plates. Neither continental plate will subduct. It is likely that the plate may break along the boundary of continental and oceanic crust.
Tectonic plates are composed of the oceanic lithosphere and the thicker continental lithosphere, each topped by its own kind of crust. Along convergent plate boundaries , the process of subduction carries the edge of one plate down under the other plate and into the mantle .
Oceanic-Oceanic plate subduction zones comprise roughly 40% of all subduction zone margins on the planet. The ocean-ocean plate relationship can lead to subduction zones between oceanic and continental plates, therefore highlighting how important it is to understand this subduction setting.
The continental crust on the downgoing plate is deeply subducted as part of the downgoing plate during collision, defined as buoyant crust entering a subduction zone. An unknown proportion of subducted continental crust returns to the surface as ultra-high pressure (UHP) metamorphic terranes, which contain metamorphic coesite and/or diamond plus or minus unusual silicon-rich garnets and/or ...
It runs along an oceanic-continental boundary, where the oceanic Nazca plate subducts beneath the continental South American plate. Oceanic trenches are 50 to 100 kilometers (30 to 60 mi) wide and have an asymmetric V-shape, with the steeper slope (8 to 20 degrees) on the inner (overriding) side of the trench and the gentler slope (around 5 ...