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An upper mantle body is a geological region where upper mantle rocks outcrop on the surface of the Earth (including the ocean floor). Upper mantle outcrops include: upper mantle made at constructive plate boundaries, but preserved in ophiolites, for example Isabela ophiolite in the Philippines [1] upper mantle above subduction zones, so called ...
At a subduction zone the relatively cold, dense oceanic crust sinks down into the mantle, forming the downward convecting limb of a mantle cell, which is the strongest driver of plate motion. The relative importance and interaction of other proposed factors such as active convection, upwelling inside the mantle, and tidal drag of the Moon is ...
A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density.
Subduction zone physics: Sinking of the oceanic lithosphere (sediments, crust, mantle), by the contrast of density between the cold and old lithosphere and the hot asthenospheric mantle wedge, is the strongest force (but not the only one) needed to drive plate motion and is the dominant mode of mantle convection.
Additionally, it contains mantle rock that interacts with seawater in a process known as “serpentinization,” which alters the rock’s structure and gives it a green, marble-like appearance.
On Earth, the Rayleigh number for convection within Earth's mantle is estimated to be of order 10 7, which indicates vigorous convection. This value corresponds to whole mantle convection (i.e. convection extending from the Earth's surface to the border with the core). On a global scale, surface expression of this convection is the tectonic ...
Consequently, old crust must be destroyed, so opposite a spreading center, there is usually a subduction zone: a trench where an ocean plate is sinking back into the mantle. This constant process of creating a new ocean crust and destroying the old ocean crust means that the oldest ocean crust on Earth today is only about 200 million years old ...
Scientists believe they’ve discovered an ancient ocean floor comprising a new layer between Earth’s mantle and core.