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Plates that are not subducting are driven by gravity sliding off the elevated mid-ocean ridges a process called ridge push. [4] At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Hydrothermal vents are common at spreading centers. Older rocks will be found farther away from the ...
In 1947, a team of scientists led by Maurice Ewing confirmed the existence of a rise in the central Atlantic Ocean, and found that the floor of the seabed beneath the sediments was chemically and physically different from continental crust. [54] [55] As oceanographers continued to bathymeter the ocean basins, a system of mid-oceanic ridges was ...
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.
As volcanic activity produces new oceanic crust along the ridge, the two plates diverge from each other pulling up the new ocean floor from below the crust. [31] [32] [33] Along the ocean-continent border of the tectonic plates, the oceanic plates subduct underneath the continental plates, creating some of the deepest marine trenches in the world
Tectonic plates are able to move because of the relative density of oceanic lithosphere and the relative weakness of the asthenosphere. Dissipation of heat from the mantle is the original source of the energy required to drive plate tectonics through convection or large scale upwelling and doming. As a consequence, a powerful source generating ...
At a seafloor spreading ridge, plates move away from the ridge, which is a topographic high, and the newly formed crust cools as it moves away, increasing its density and contributing to the motion. At a subduction zone the relatively cold, dense oceanic crust sinks down into the mantle, forming the downward convecting limb of a mantle cell ...
Scientists believe they’ve discovered an ancient ocean floor comprising a new layer between Earth’s mantle and core.
The depth predicted by the square root of seafloor age found by the 1974 cooling mantle derivation [4] is too deep for seafloor older than 80 million years. [5] Depth is better explained by a cooling lithosphere plate model rather than the cooling mantle half-space. [5] The plate has a constant temperature at its base and spreading edge.