Forced thrust or shear force strength is the proposed propulsion force for plate movements in plate tectonics that occur in the mountains in the middle of the sea as a result of rigid lithosphere that glide under the hot asthenosphere and lifted under the mountains in the middle of the ocean. Although called ridge push, the term is somewhat misleading; in fact this is the strength of the body that works across the oceanic plates, not just on the ridge, as a result of the pull of gravity. The name comes from the previous model of tectonic plates where the boost of the ridge is primarily thought to be derived from upwelling magma in the central mountains pushing or propping the plates apart.
Video Ridge push
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Ridge push is the result of the gravitational force acting on, the lithosphere of the young ocean raised around the mountains in the middle of the sea, causing it to slide downward with the higher but weaker asthenosphere and pushing on the lithosphere material farther away from the mountains.
The seaweed algae is a long chain of undersea volcanoes that occur at divergent plate boundaries in the oceans, where new oceanic crust is formed by upwelling mantle material as a result of tectonic plate spreading and relatively shallow decompression melting (above ~ 60 km). The upwelling coat and the fresh crust are hotter and less dense than the surrounding crust and mantle, but cool and contract with age until it reaches equilibrium with an older crust around 90 Ma. This results in an isostatic response that causes the youngest areas closest to plate boundaries to rise above older areas and gradually drown with age, resulting in a morphology of the ridge in the middle of the ocean. The greater heat on the ridge also weakens the rock closer to the surface, increasing the boundary between the weak and weak lithosphere, the ductal asthenosphere to create elevated features and a similar angle under the ridge.
The features that this generates generate a bulge push; The gravity that attracts the lithosphere on the ridge in the middle of the sea is largely opposed by the normal forces of the underlying rock, but the rest acts to push the lithosphere down the asthenosphere and away from the ridge. Because the asthenosphere is weak, the push ridge and other driving forces are sufficient to damage it and allow the lithosphere to shift upwards, opposed by obstacles in the Litosphere-Astenosphere boundary and resistance to subduction at the boundaries of the converging plate. Ridge push is mostly active in lithosphere younger than 90 Ma, after which it has been cool enough to achieve thermal equilibrium with older material and the slope of the Litosphere-Astenosphere limit to zero effectively.
Maps Ridge push
History
Initial Idea (1912-1962)
Despite its current status as one of the driving forces of plate tectonics, the ridge's drive is not included in any of Alfred Wegener's proposals in 1912-1930 about continental drift, produced before the discovery of the mountains in the oceans and lacking any concrete mechanism. the process may have occurred. Even after the development of audible acoustic depth and the discovery of global oceans in the 1930s, the idea of ​​dispersive forces acting on the ridge was not mentioned in the scientific literature until Harry Hess's proposal of seafloor spread in 1960, which included pushing the forces in the mountains in the middle sea ​​as a result of upwelling magmas clamping the lithosphere apart.
Gravity Model (1964-Present)
In 1964 and 1965, Egon Orowan proposed the first gravitational mechanism to spread in the mountains in the middle of the sea, postulated that the dispersion could be derived from the principles of isostation. In Orowan's suggestion, the pressure inside and immediately below the high ridge is greater than the pressure on the oceanic crust on either side because of the greater rock weight on it, forcing the material away from the ridge, while the low density of the ridge material is relative to the surrounding crust will gradually compensate for a larger volume of rock to the depth of isostatic compensation. A similar model was proposed by Lliboutry in 1969, Parsons and Richer in 1980, and others. In 1969, Hales proposed a model in which the elevated lithosphere of the mountains in the middle of the ocean slid down the high ridge, and in 1970 Jacoby proposed that the less dense materials and isostation of Orowan and other proposals resulted in removal resulting in glide similar to the Proposal hales. The term "ridge of thrust force" was created by Forsyth and Uyeda in 1975.
Significance
Early tectonic plate models, such as the Harry Hess seabed model, assume that plate motion and mountain activity and subduction zones in the middle of the ocean are the result of current convection in mantles dragging the crust and supplying fresh, hot magma in the mountains in the middle of the ocean. Further developments of the theory suggest that some forms of ridge impulse help complete the convection to keep the plate moving, but in the 1990s, the calculations showed that the tensile plate, the force to which the sub-plate portion was applied to the crust was attached to the surface. , is an order of magnitude stronger than a ridge impulse. In 1996, slab pull was generally regarded as the dominant mechanism of tectonic plate propulsion. Modern studies, however, show that the pull effect of the slab is largely negated by forces that resist the mantle, limiting only 2-3 times the effective strength of the ridge thrust force in most plates, and the coat's convection may be too slow to drag between the lithosphere and the asthenosphere to explains the observed plate movement. This restores the boost of the ridge as one of the dominant factors in plate motion.
Fighting Forces
Ridge push is mainly opposed by plate drag, which is the drag force of the rigid lithosphere that travels over the weak and brittle asthenosphere. The model estimates that the ridge impulse may be just enough to overcome the drag plate and maintain plate movement in most areas. The pull slab is also opposed by resistance to lithospheric subduction into the mantle at the boundaries of the converging plate.
Leading Qualification
Research by Rezene Mahatsente suggests that driving pressures caused by ridge impulses will be lost due to faults and earthquakes in plates containing large amounts of unbound water, but they conclude that the ridge impulse is still a significant driving force in existing plates due to earthquake rarity earth intraplate in the ocean.
In plates with very small or small subduction plates, the driving ridge may be the main driving force in plate motion. According to Stefanick and Jurdy, the backstroke force acting on the South American plate is about 5 times the tensile strength of the plates acting on the subduction margin due to the small size of the subduction plate at Scotia and Caribean margins. The Nazca plate also experiences a relatively small pull of the slab, more or less the same as its back impulse, due to the young plates (not more than 50 million years) and therefore less dense, with less tendency to sink into the mantle. This also causes the subducted Nazca plate to subduct flat plate, one of the few places in the world where it currently occurs.
References
Source of the article : Wikipedia
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