Oceanic Foundation
Description: Oceanic plate – Oceanic plate collision, Oceanic plate – Continental plate collision, Convergence (oceanic crust), Convergent boundaries, Convergent (Oceanic-Oceanic), plate tectonics, Converging of Continental and Oceanic Plate #convergentPlateBoundary
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Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate . The crust overlies the solidified and uppermost layer of the mantle . The crust and the solid mantle layer together comprise oceanic lithosphere .
Oceanic crust is the result of erupted mantle material originating from below the plate, cooled and in most instances, modified chemically by seawater. This occurs mostly at mid-ocean ridges, but also at scattered hotspots, and also in rare but powerful occurrences known as flood basalt eruptions. It is primarily composed of mafic rocks, or sima , which is rich in iron and magnesium. It is thinner than continental crust , or sial , generally less than 10 kilometers thick; however it is denser, having a mean
Although a complete section of oceanic crust has not yet been drilled, geologists have several pieces of evidence that help them understand the ocean floor. Estimations of composition are based on analyses of ophiolites (sections of oceanic crust that are preserved on the continents), comparisons of the seismic structure of the oceanic crust with laboratory determinations of seismic velocities in known rock types, and samples recovered from the ocean floor by submersibles , dredging (especially from ridge c
Oceanic Foundation