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Define sea floor spreading and its significance for oceanic crust. Sea-floor spreading involves divergence of adjacent tectonic plates on the ocean bottom caused by convection currents in the mantle. New oceanic crust forms from cooling and crystallization of lava that flows out of this divergent plate boundary from Earth's interior.
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust , composed of troctolite , gabbro and ultramafic cumulates .
oceanic crust, the outermost layer of Earth’s lithosphere that is found under the oceans and formed at spreading centres on oceanic ridges, which occur at divergent plate boundaries. Oceanic crust is about 6 km (4 miles) thick. It is composed of several layers, not including the overlying sediment.
26 Απρ 2024 · The theory of plate tectonics states that Earth’s solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle. Oceanic and continental plates come together, spread apart, and interact at boundaries all over the planet.
It's relatively thin compared to the Earth's mantle and core, but it's the part we interact with directly. The crust is divided into two main types: continental crust, which is thicker and less dense, and oceanic crust, which is thinner and denser. How is oceanic crust different from continental crust.
As we discussed in Chapter 10, oceanic crust is formed at sea-floor spreading ridges from magma generated by decompression melting of hot upward-moving mantle rock (Figure 10.18). About 10% of the mantle rock melts under these conditions, producing mafic magma.
