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Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) 'pertaining to building') [1] is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago.
Plate tectonics was a suitable explanation for seafloor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a major paradigm shift in geological thinking. It is estimated that along Earth's mid-ocean ridges every year 2.7 km 2 (1.0 sq mi) of new seafloor is formed by this process. [50]
The Vine–Matthews–Morley hypothesis, also known as the Morley–Vine–Matthews hypothesis, was the first key scientific test of the seafloor spreading theory of continental drift and plate tectonics. Its key impact was that it allowed the rates of plate motions at mid-ocean ridges to be computed.
Continental-continental divergent/constructive boundary Oceanic divergent boundary: mid-ocean ridge (cross-section/cut-away view). In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.
Despite their appearance, in these instances the fundamental plate-tectonic structure is still an oceanic trench. Some troughs look similar to oceanic trenches but possess other tectonic structures. One example is the Lesser Antilles Trough, which is the forearc basin of the Lesser Antilles subduction zone. [8]
The Wilson cycle theory is based upon the idea of an ongoing cycle of ocean closure, continental collision, and a formation of new ocean on the former suture zone.The Wilson Cycle can be described in six phases of tectonic plate motion: the separation of a continent (continental rift), formation of a young ocean at the seafloor, formation of ocean basins during continental drift, initiation of ...
The Azores triple junction is a geologic triple junction where the boundaries of three tectonic plates intersect: the North American plate, the Eurasian plate and the African plate, R-R-R. [9] The Boso triple junction offshore of Japan is a T-T-T triple junction between the Okhotsk microplate, Pacific plate and Philippine Sea plate.
The Pacific plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million km 2 (40 million sq mi), it is the largest tectonic plate. [2] The plate first came into existence as a microplate 190 million years ago, at the triple junction between the Farallon, Phoenix, and Izanagi plates. The Pacific plate subsequently grew ...