Tectonic plate theory

Plate tectonics The theory that posits crustal plate movement is caused by seafloor spreading and subduction. 

Plate tectonics A theory that states that the Earth s lithosphere is divided into several sections or plates that collide, separate, or slide past each other over geologic time. 

Tectonic plate A section of the Earth s lithosphere (the crusts and underlying rigid upper mantle) that slowly moves on the underlying plastic asthenosphere. The Earth s lithosphere is divided into about 15 tectonic plates. Some plates consist entirely of oceanic crust, while others have substantial continental crust. The movement of tectonic plates over time is described by the theory of plate tectonics. 

Forty years ago, our understanding of how the Earth works was revolutionized by the theory of Plate Tectonics. This theory, however, only described the workings of the solid Earth, with a particular emphasis on the origin of ocean basins and active mountain belts. In contrast, Earth System Science is about much... 

Data obtained from many sources led scientists to develop the theory of plate tectonics. This theory is the most current model that explains not only the movement of the continents, but also the changes in the earth s crust caused by internal forces. 

The observations described above are explained by the theory of plate tectonics. This theory views Earth s solid siuface as consisting of several rigid plates that move relative to each other. These plates drift at an average rate of several centimeters per year atop a relatively weak, partially molten layer that is part of... 

Many properties and characteristics of the Earth are determined by plate tectonics, according to the theory of which the lithosphere is not a closed shell instead it consists of about a dozen large, rigid plates. These are constantly in motion—on a geological timescale. Each of the plates moves as an independent unit and swims on the softer, but more dense, asthenosphere (Press and Siever, 1995). 

Until the arrival of the theories of plate tectonics and seafloor spreading in the 1960s, the Earth s mantle was generally believed to consist... 

Tackley P. J. (2000) Mantle convection and plate tectonics toward an integrated physical and chemical theory. Science 288, 2002-2007. 

Quantitative studies of mantle mixing evolved from early laboratory and numerical experiments that linked plate tectonics with convection in the planetary mantle (McKenzie, 1969 Richter, 1973 McKenzie et al., 1974 Richter and Parsons, 1975). The finite strain theory for the development of seismic anisotropy can be used to describe the deformation and subsequent mixing of mantle... 

Theories that attempt to explain the formation of the specific structures of the Earth are at least as numerous as those for the formation of the universe. Although the details of these theories differ, there is general agreement that the Earth was much hotter during its early life, and that the materials fractionated into gaseous, liquid, and solid states at that time. As the surface of the Earth cooled, the lighter materials in the crust solidified and still float on a molten inner layer, according to the plate tectonics... 

Earthquakes and volcanic activity are commonly associated with trenches, hi fact, the trenches that encircle the Pacific Ocean are sometimes called the Ring of Fire because of the volcanic activity located there. According to the plate tectonic theory, trenches form at sites where one lithospheric plate is forced beneath another, or subducted, as a result of seafloor spreading elsewhere. Friction between the two plates is responsible for the associated earthquakes and volcanic activity. 

In accord with plate tectonic theory. Earth s crust and upper mantle, or lithosphere, consists of about 20 large segments, known as plates, that are about 60 mi (100 km) thick and thousands of miles wide. These plates slide back and forth on top of a lower layer of material known as the asthenosphere. The plates collide with each other head on, slide back and forth against each other, and pull apart from each other. Significant geological events, such as volcanoes and earthquakes, are produced. 

Of course in order to satisfactorily refute a scientific theory it is important to provide a better explanation of the facts. In the case of mantle plumes it is suggested that plate tectonic processes can explain all the features ascribed to mantle plumes. In the case of hot spots this may be achieved by combining a source of melt in the upper mantle with either a propagating fracture zone or with continental margin-edge driven convection in the shallow mantle (Foulger Natland, 2003). 

The theory of plate tectonics provides a succinct modern example of the transformation of a scientific field toward a conceptual structure that includes the six concepts emphasized in this chapter. 

Another example of a paradigm shift is the acceptance of plate tectonics as the explanation for large-scale movements in the Earth s crust. Advances in seismic imaging and observation techniques allowed for the collection of sufficient data to establish plate tectonics as a legitimate geological theory. 

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