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The asthenosphere is a part of the upper mantle just below the lithosphere that is involved in plate tectonic movement and isostatic adjustments. It is composed of peridotite, a rock containing mostly the minerals olivine and pyroxene. [2] The lithosphere-asthenosphere boundary is conventionally taken at the 1,300 °C (2,370 °F) isotherm.
The lithosphere–asthenosphere boundary (referred to as the LAB by geophysicists) represents a mechanical difference between layers in Earth's inner structure. Earth's inner structure can be described both chemically ( crust , mantle , and core ) and mechanically.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
Mechanically, it can be divided into lithosphere, asthenosphere, mesospheric mantle, outer core, and the inner core. Chemically, Earth can be divided into the crust, upper mantle, lower mantle, outer core, and inner core. [6] The geologic component layers of Earth are at increasing depths below the surface. [6]: 146
Below the asthenosphere, the mantle is again relatively rigid. The Earth's mantle is divided into three major layers defined by sudden changes in seismic velocity: [ 6 ] the upper mantle (starting at the Moho, or base of the crust around 7 to 35 km [4.3 to 21.7 mi] downward to 410 km [250 mi]) [ 7 ]
As delamination continues, more asthenosphere rises to replace the lower lithosphere as it sinks. This process causes three different changes to occur which can have an effect on the delamination process. [1] If the viscosity of the upwelling asthenosphere is greater than that of the mantle lithosphere, delamination will stop.
Geology portal; Asthenosphere – Highly viscous, ductile, and mechanically weak region of Earth's mantle; Continent – Large geographical region identified by convention; Craton – Old and stable part of the continental lithosphere Platform – A continental area covered by relatively flat or gently tilted, mainly sedimentary strata
In geology, the low-velocity zone (LVZ) occurs close to the boundary between the lithosphere and the asthenosphere in the upper mantle. It is characterized by unusually low seismic shear wave velocity compared to the surrounding depth intervals. This range of depths also corresponds to anomalously high electrical conductivity.