This makes plate convergence responsible for nearly all volcanic activity on Earth. Here we should also note that Pacific Ring of Fire, where subduction is taking place at numerous trenches that border the continental shores, has 450 volcanoes, more than 75% of all the volcanoes on Earth. The most visible example is Andes Mountains off the west coast of the U.S. Continental volcanic arcs are chains of volcanoes found on the margin of the continent above a subduction zone at ocean-continent boundaries. At ocean-continent boundaries, the resulting body of volcanoes is called a continental volcanic arc. Thus Volcanoes are common on Ocean-Continent Boundary also. When the oceanic plate is subducted under the continental plate, it leads to the generation of new magma, which upwells and forms volcanoes on the non-subducting plate, or the continental plate. When an oceanic plate collides with a continental plate, the oceanic plate is always pulled under and subducted because it is denser than the continental plate. Ocean-Continental Convergent BoundaryĬonvergence of an oceanic plate with a continental plate is similar to ocean-ocean convergence and often results in the volcanic. All of them have developed parallel to the direction of subduction. Examples of such arcs are Japan, the Philippines, the Tonga Islands, the Aleutian Islands, and the West Indies Islands etc. Thus, Island volcanic arcs are a chain of islands and mountains that form on the overriding or non-subducting oceanic plate. An island volcanic arc may include islands that develop in the sea from the build-up of volcanic rocks. Island Volcanic ArcĪt ocean-ocean convergent boundaries, the resulting body of many volcanoes is called an island volcanic arc. Areas of ocean-ocean convergence are characterized by ocean trenches, seafloor volcanoes, and volcanic islands. Therefore it easily rises and erupts on the seafloor, ultimately building a volcano or a volcanic island in the sea. Please note that when one oceanic plate is subducted under the other, the resulting new magma is less dense than the surrounding rock. Such boundary would be called an Ocean-ocean convergent plate boundary. It descends into the asthenosphere, or upper mantle, where it will lead to the generation of new magma. When two oceanic plates meet and collide against each other, the denser of the two plates is pulled under the other and is subducted. There are following types of Convergent Boundaries: Ocean-Ocean Convergent Plate Boundary The convergent plate boundaries are also responsible for nearly 75% of Earth’s volcanoes. Comparison: Divergent and Convergent Plate Boundaries.Transform Plate Boundaries: where plates slide past one another.Divergent Plate boundaries: where plates move away from each other.Convergent Plate Boundaries: where plates move toward each other.There are three types of plate boundaries: Plate interiors have much fewer earthquakes. The plate boundaries can be identified because they are zones along which maximum earthquakes occur. While the continents do indeed appear to drift, they do so only because they are part of larger plates that float and move horizontally on the upper mantle asthenosphere. The above discussed Lithospheric Plates are composed of lithosphere, about 100 km thick, that “float” on the plastic asthenosphere. The recent studies show that they may be different parts of two different plates. The Austral-Indian plate is mostly oceanic lithosphere but contains two cores of continental lithosphere– Australia and peninsular India.The continent of Antarctica forms a central core of continental lithosphere completely surrounded by oceanic lithosphere. This means that the other plates are moving away from the pole. The Antarctic plate is almost completely enclosed by a spreading plate boundary.The great Pacific plate occupies much of the Pacific Ocean basin and consists almost entirely of oceanic lithosphere.It is a mix of continental and oceanic lithosphere. African Plate is also known as the Nubia Plate.Most part of the Eurasian plate is continental lithosphere, but it is fringed on the west and north by a belt of oceanic lithosphere.American plate includes most of the continental lithosphere of North and South America.Some important notable observations about these plates are as follows: The below graphics shows these Lithospheric Plates. Apart from those, there are some lesser plates and sub plates also. Pacific, American, Eurasian, African, Austral-Indian, and Antarctic. The Earth’s surface is composed of six major lithospheric plates’ viz.
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