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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.
16 Νοε 2018 · Oceanic crust is created at mid-ocean ridges as plates diverge and magma rises from the upper mantle and crust. As the crust moves away from the ridge, it cools and becomes denser while sediment builds on top. The youngest crust is at the ridges and gets progressively older further away.
1 Ιαν 2018 · Oceanic crust is the outermost solid layer of the lithospheric tectonic plates under the oceans that covers much of the Earth’s surface. It has a distinctive basaltic composition characterized by rocks that have relatively low concentrations of potassium and other highly incompatible trace elements (those typically excluded from minerals that ...
Oceanic crust is created as magma rises to fill the gap between diverging tectonic plates and is consumed in subduction zones. It is geologically young, with a mean age of 60.
24 Απρ 2024 · The age of the oceanic crust has been determined by systematic mapping variations in the strength of the Earth’s magnetic field across the sea floor and comparing the results with our understanding of the record of Earth’s magnetic field reversal chronology for the past few hundred million years.
• Describe the various components of oceanic crust: pillow basalts, sheeted dykes, gabbro bodies, layered gabbro, and layered ultramafic rock. • Describe the age distribution of oceanic crust, and explain why all of it is relatively young.
18.2 The Geology of the Oceanic 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 10.4.3). About 10% of the mantle rock melts under these conditions, producing mafic magma.
