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Convergent boundaries, where 2 plates are moving toward each other, are of three types, depending upon the type of crust existing on either next of the border — oceanic or continental. The species are ocean-ocean, ocean-continent, and also continent-continent.

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At one ocean-ocean convergent boundary, one of the plates (oceanic crust and also lithospheric mantle) is pushed, or subducted, under the various other (Figure (PageIndex1)). Regularly it is the older and colder plate that is denser and subducts beneath the younger and warmer plate. Over there is typically an s trench follow me the boundary together the late bends downwards. The subducted lithosphere descends into the warm mantle at a fairly shallow edge close come the subduction zone, however at steeper angle farther under (up to about 45°). The significant volume of water in ~ the subducting product is released together the subducting late is heated. The mixes with the overlying mantle, and also the enhancement of water come the hot mantle lowers the crust’s melting suggest and leads to the formation of magma (flux melting). The magma, i m sorry is lighter 보다 the surrounding mantle material, rises with the mantle and also the overlying oceanic crust to the s floor whereby it creates a chain of volcanic islands recognized as one island arc. A tires island arc creates into a chain of relatively huge islands (such together Japan or Indonesia) as more and more volcanic product is extruded and sedimentary rocks accumulate about the islands. Earthquakes occur relatively deep below the seafloor, whereby the subducting crust moves versus the overriding crust.

Figure (PageIndex1) A trench and volcanic island created from one ocean-ocean convergent zone (Steven Earle, “Physical cg-tower.comlogy”).

Examples of ocean-ocean convergent zones space subduction that the Pacific Plate southern of Alaska (creating the Aleutian Islands) and also under the Philippine Plate, wherein it creates the Marianas Trench, the deepest part of the ocean.

At one ocean-continent convergent boundary, the denser oceanic bowl is driven under the less thick continental bowl in the very same manner together at an ocean-ocean boundary. Sediment the has collected on the seafloor is thrust up into an accretionary wedge, and compression leads to thrusting in ~ the continental plate (Figure (PageIndex2)). The magma produced nearby to the subduction ar rises to the base of the continent crust and also leads to partial melt of the crustal rock. The result magma ascends through the crust, producing a hill chain with plenty of volcanoes. Similar to an ocean-ocean boundary, the subducting tardy can create a deep trench running parallel to the coastline.

Figure (PageIndex2) A trench and also volcanic mountains developed from an ocean-continent convergent ar (Steven Earle, “Physical cg-tower.comlogy”).

Examples of ocean-continent convergent borders are subduction that the Nazca bowl under south America (which has developed the Andes Mountains and also the Peru Trench) and also subduction of the Juan de Fuca key under north America (creating the Cascade Range).

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A continent-continent collision occurs once a continent or big island that has been moved along with subducting oceanic late collides with one more continent (Figure (PageIndex3)). The colliding continental product will no be subducted since it is also light (i.e., due to the fact that it is composed mostly of light continent rocks), yet the root of the oceanic plate will at some point break off and sink right into the mantle. Over there is tremendous deformation the the pre-existing continent rocks, forcing the product upwards and creating mountains.