asthenosphere
Image credit: Massey University
The uppermost layer of the mantle of a rocky planet, located below the lithosphere. On Earth, this zone of soft, easily deformed rock lies at depths of about 100 to 250 km.
asthenosphere Layer of Earth's interior, just below the lithosphere, over which the surface plates slide.
ASTHENOSPHERE
The asthenosphere is a part of the upper mantle that exhibits plastic (flowing) properties. It is located below the lithosphere (the crust and rigid upper mantle), between about 100 and 250 kilometers deep.
As the asthenosphere moves slowly, the crust on top of it also moves. In certain locations the crust can be broken apart due to the motion of the asthenosphere in differing directions.
asthenosphere (NASA Thesaurus) Layer or shell of the Earth below the lithosphere which is weak and in which isostatic adjustments take place, magmas may be generated, and seismic waves are strongly attenuated.
When oceanic crust runs into oceanic crust or into continental crust, the denser lithosphere material slides under the less dense lithosphere material and melts in the asthenosphere.
Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides.
The lithosphere essentially floats on the asthenosphere and is broken up into what are called tectonic plates.
The upper mantle is separated from the crust above by a seismic discontinuity, called the Moho, and from the lower mantle below by a zone of weakness known as the asthenosphere.
The theory of plate tectonics states that the lithosphere is divided into plates which interact with each other and float around the planed on the asthenosphere.
These and other minerals are refractory and crystalline at high temperatures; therefore, most settle out of rising magma, either forming new crustal material or never leaving the mantle. Part of the upper mantle called the asthenosphere might be ...
Beneath the lithosphere at ~72-250 km depth, is the low-velocity zone; also called the asthenosphere. A rapid increase of seismic velocities occurs at ~670; this corresponds to a mantle phase change.
The denser lithospheric plates (60 kilometres thick beneath the oceans and ranging from about 100-200 kilometres beneath the continents) ride on a weak, perhaps partially molten, layer of the upper mantle called the asthenosphere.
 See also: Lithosphere, Earth, Crust, Ocean, Mass
|
