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The mantle within about 200 km (120 mi) above the core–mantle boundary appears to have distinctly different seismic properties than the mantle at slightly shallower depths; this unusual mantle region just above the core is called D″ ("D double-prime"), a nomenclature introduced over 50 years ago by the geophysicist Keith Bullen. [26]
The silicate mantle of the Earth's moon is approximately 1300–1400 km thick, and is the source of mare basalts. [4] The lunar mantle might be exposed in the South Pole-Aitken basin or the Crisium basin. [4] The lunar mantle contains a seismic discontinuity at ~500 kilometers (310 miles) depth, most likely related to a change in composition. [4]
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 ...
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 ...
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.
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 ...
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.
The transition zone is located between the upper mantle and the lower mantle between a depth of 410 km (250 mi) and 670 km (420 mi).. This is thought to occur as a result of the rearrangement of grains in olivine to form a denser crystal structure as a result of the increase in pressure with increasing depth. [6]