The driving forces of plate tectonics has long been debated. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches. Seafloor spreading takes place at midocean ridges and produces basalt, the rock that makes up the oceanic crust. Anyway, if you can elaborate on your question a bit more to describe why your profs bought into slab pull, what you thought was lacking in the textbooks, and why ridge push interests you as a possibility, then ill release this. However, there is now a good agreement that slab pull is the main driving force of plate tectonics. In 1975 forsyth and uyeda used the inverse theory method to show that, of the many forces likely to be driving plate motion, slab pull was the strongest. The tectonic plates that make up the earths crust are in constant motion. It was once thought that mantle convection could drive plate motions. Lima explains how mantle convection and gravity through ridge push and slab pull help move tectonic plates. However, ridge push is still considered to be of significance, especially where there is little or no slab pull acting on the plate eg the antarctic plate mentioned above. In the current understanding of plate motion the movement is driven by the weight of cold, older, dense plate material sinking into the mantle at deep ocean trenches and. In this lesson, we explore the causes of plate movement, including thermal convection, ridge push and slab pull. Ridge push, also known as gravitational sliding, is the gravity pull on the lithosphere due to the higher elevation of the midocean ridges.
Ridge push or sliding plate force is a proposed mechanism for plate motion in plate tectonics. The slab pull drives oceanic plates to move away from oceanic spreading centers. What causes some plates to move faster than others. Mechanisms for plate motion geosciences libretexts. This animation of seafloor spreading and plate tectonic evolution of the planet since 200 million years ago is from noaas science on a sphere series. It shows how the continents moved apart and, in some cases, stitched back together. Answer the supercontinent cycle consists of fragmentation. Plate motion by alham ahmadzai transform a transform fault or transform boundary, is a type of fault whose relative motion is.
Slab pull and the seismotectonics of subducting lithosphere. How have slab pull and ridge push, both mainly gravity driven. Slab pull is the pull force exerted by a dense oceanic plate as it descends into the mantle at a. Slab pull is the pulling force exerted by a cold, dense oceanic plate plunging into the mantle due to its own weight. The history of the development of plate tectonics is centrally tied to the question of what drives plate motions. The pacific ocean floor moves much quicker than the atlantic because it has both slab pull and ridge push acting on it, while the atlantic only ha ridge push probably the weaker of the two forces. Lithospheric plates are part of a planetary scale thermal convection system.
Subduction, ridge push, slab pull flashcards quizlet. There have been two main models of ridge push proposed by geologists. Click the picture to see an animation that shows both seafloor spreading and magnetic reversals. Dynamic earth mantle convection this page from the university of leeds gives an introduction to the drivers of plate tectonics, including links to illustrations depicting ridge push slab pull, ridge bathymetry, mantle tomographic data, plumes, and other topics. The ridge push slab pull model also relies on mantle convection, but in this case it is not simply the traction from the convection cell that moves the plates.
Seafloor spreading animation earthguide online classroom. Slab pull demo how tectonic plates can pull on each other to speed subduction using paper clips duration. Midocean ridges reach a typical summit elevation of 2,700 meters below sealevel. Ridgepush forces are thought to be second in importance only to the forces of slab pull. At midocean ridges buoyant upwelling mantle comes close to the surface and partially melts to create new oceanic lithosphere. Compare and contrast ridgepush and slabpull answers. Answer the supercontinent cycle consists of fragmentation of a supercontinent from geo 111 at owens state community college. Several mechanisms have been proposed, mainly ridge push, mantle drag, and slab pull see this page from the british geological survey. A midocean ridge or midoceanic ridge is an underwater mountain range, formed by plate tectonics. Whats the difference between slab pull and subduction. They are the shallowest major features of the seafloor. Slab pull is caused by the weight of a subducting plate pulling the trailing slab into the subduction zone much like a tablecloth slipping off the table can pull articles off with it. Mantle convection currents, ridge push and slab pull are three of the forces that have been proposed as the main drivers of plate movement based on what drives the plates. Forces that cause what drives plate motion several mechanisms contribute to plate motion that include slab pull, ridge push, and slab suction.
Plates are extremely heavy so gravity acts upon them, pulling them apart. The creationists concluded that slab pull was the primary mechanism. Further developments of the theory suggested that some form of ridge push helped supplement convection in order to keep the plates moving, but in the 1990s, calculations indicated that slab pull, the force that a subducted section of plate exerts on the attached crust on the surface, was an order of magnitude stronger than ridge push. Slab pull happens at subduction zones where one plate is pulled down into the mantle. Slab pull is essentially the wieght of the a downgoing oceanic slab in a subduction zone. Interactions between the forces that drive and resist plate motions cause spatially and temporally localized. In this model, plates move through a combination of pull from the weight of the subducting edge of the plates, and through the outward pushing of an ocean ridge where magma is rising and forming new crust figure \\pageindex2\. Which of the following is a result of gravity in relation. Slab pull is created by the motion of one tectonic plate as it moves beneath another. Slab pull is is tectonic plate motion due to higher densities. This force is regarded as a secondary force and is referred to by some as ridge push. Slab pull is the dominant force driving plate motion, the other major one is ridge push sometimes called ridge slide. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
It means that it is the subducting plate which controls the velocity of the plates movement. Slab pull is thought to be a more significant gravitational force acting on plates. Plate tectonicswhat are the forces that drive plate. Ridge push is caused by the potential energy gradient from the high topography of the ridges.
The midatlantic ridge and east pacific rise are examples of midocean ridges. The energy source for plate tectonics is earths internal heat while the forces moving the plates are the ridge push and slab pull. Internet sites, videos, software, and demonstration aids internet sites 1. This is because it cools as it moves away from the ridge and the boundary between the solid lithosphere and slightly molten asthenosphere becomes deeper the. As the slab subducts under another plate either oceanic or continental gravity pulls the plate down into the mantle. Slab pull is caused by the negative buoyancy of the subducting plate.
What is a ridgepush, slabpull, shearing, and convection. K ey v ocabulary mantle convection ridge push slab pull 8. This has been the case since the failure of wegeners ideas about polflucht to explain continental drift to the seminal papers by elsasser, solomon and sleep, and forsyth and uyeda on slab pull and ridge push. Ridge push happens at spreading centers where plates are moving apart. Use the socrative site room 68277 to take a practice test on plate tectonics.
What is the differences between slab pull and ridge push. Drives motion of mantle convection through slab pull and ridge push. But in the pacific the mid ocean ridge is much smooth it more like hills. This synthesis links many seismic and tectonic processes at subduction zones, including great subduction earthquakes, to the sinking of subducted plate.
However, this idea has now changed with the main mechanism determined to be slab pull. Because midocean ridges lie at a higher elevation than the rest of the ocean floor, gravity causes the ridge to push on the lithosphere that lies farther from the ridge. Slab pull, slab trench suction and ridge push forces drive plate motion slab resistance, continental reistance, transform fault resistance and basal drag oppose plate motion when resisting forces become greater than the driving forces, collision between the plates will eventually cease. Slap pull, on the other hand, is the gravitational force acting on plates due tho the increased weight of the cold and old plate material. Another force, that for some plates exceeds ridgepush, is slab pull, where the weight of a subducting slab pulls the plate at the surface along. Alternatively, as shown in the diagram, convection currents under the.
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