These are sometimes characterized as “conveyor-belts” because they are the one site on the planet where new oceanic lithosphere is constantly created. The places where we find mid-ocean ridges are called spreading centers. As this process evolves, a mid-ocean ridge forms above the rift on the floor of the new ocean because the cooling lava is hot and less dense (i.e., it takes up more space than cold material). Once continental lithosphere has thinned and become mafic, upwelling magma produces new oceanic lithosphere and a narrow ocean basin forms between the rifted continents (review video in previous sections). Mid-ocean ridges typically follow the long process of continental rifting. The reason these spreading centers along the ocean floor are essential for plate tectonics is that they represent a simple example of a divergent boundary. We have previously discussed the discovery of mid-ocean ridges as a key piece of evidence for the theory of plate tectonics. A divergent boundary may also form beneath the oceanic lithosphere, where mantle convection cells cause the plates to push apart and form a mid-ocean ridge.
0 Comments
Leave a Reply. |