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  2. Oceanic crust - Wikipedia

    en.wikipedia.org/wiki/Oceanic_crust

    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. [1] [2] The crust overlies the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere. Oceanic crust is primarily ...

  3. Ophiolite - Wikipedia

    en.wikipedia.org/wiki/Ophiolite

    Scientists have drilled only about 1.5 km into the 6- to 7-kilometer-thick oceanic crust, so scientific understanding of oceanic crust comes largely from comparing ophiolite structure to seismic soundings of in situ oceanic crust. Oceanic crust generally has a layered velocity structure that implies a layered rock series similar to that listed ...

  4. Sima (geology) - Wikipedia

    en.wikipedia.org/wiki/Sima_(geology)

    In geology, sima (/ ˈ s aɪ m ə /) is an antiquated [1] blended term for the lower layer of Earth's crust. This layer is made of rocks rich in magnesium silicate minerals. Typically, when the sima comes to the surface, it is basalt, so sometimes this layer is called the 'ocean layer' of the crust. The sima layer is also called the 'basal ...

  5. Mid-ocean ridge - Wikipedia

    en.wikipedia.org/wiki/Mid-ocean_ridge

    The overall shape of ridges results from Pratt isostasy: close to the ridge axis, there is a hot, low-density mantle supporting the oceanic crust. As the oceanic plate cools, away from the ridge axis, the oceanic mantle lithosphere (the colder, denser part of the mantle that, together with the crust, comprises the oceanic plates) thickens, and ...

  6. Earth's mantle - Wikipedia

    en.wikipedia.org/wiki/Earth's_mantle

    The mantle's composition has changed through the Earth's history due to the extraction of magma that solidified to form oceanic crust and continental crust. It has also been proposed in a 2018 study that an exotic form of water known as ice VII can form from supercritical water in the mantle when diamonds containing pressurized water bubbles ...

  7. Marine geology - Wikipedia

    en.wikipedia.org/wiki/Marine_geology

    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

  8. A geologist has found part of a lost ocean that existed long ...

    www.aol.com/article/2016/08/15/geologist-found...

    NASA/Goddard Space Flight Center The roughly 60,000-square-mile piece of crust has been hiding below the eastern Mediterranean Sea for about 340 million years (give or take 30 million years).

  9. Continental margin - Wikipedia

    en.wikipedia.org/wiki/Continental_margin

    The denser oceanic crust of one plate subducts below the less dense continental crust of another plate. Convergent active margins are the most common type of active margin. Transform active margins are more rare, and occur when an oceanic plate and a continental plate are moving parallel to each other in opposite directions.