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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.
Geothermal gradient. Temperature profile of inner Earth, schematic view (estimated). The red dashed line shows the minimum temperature for the respective mantle rock to melt. The geothermal gradient remains below the melting temperature of the rock, except in the asthenosphere. Sharp rises occur in the uppermost mantle and at the core–mantle ...
Subduction. Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle.
Earthquakes are primarily constrained to occur within the old, cold, lithosphere to temperatures of up to ~650 °C. [3] This criterion works particularly well in oceanic lithosphere, where it is reasonably simple to estimate the temperature at depth based upon the age of the rocks. [4] The LAB is most shallow when using this definition.
Mantle convection. Simplified model of mantle convection: [1] Whole-mantle convection. Mantle convection is the very slow creep of Earth's solid silicate mantle as convection currents carry heat from the interior to the planet's surface. [2][3] Mantle convection causes tectonic plates to move around the Earth's surface. [4]
As the slab sinks deeper into the mantle, it releases water from dehydration of hydrous minerals in the oceanic crust. This water reduces the melting temperature of rocks in the asthenosphere and causes partial melting. Partial melt will travel up through the asthenosphere, eventually, reach the surface, and form volcanic island arcs.
The internal structure of Earth are the layers of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere, and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core. Scientific understanding of the internal ...
A thermocline (also known as the thermal layer or the metalimnion in lakes) is a distinct layer based on temperature within a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) with a high gradient of distinct temperature differences associated with depth. In the ocean, the thermocline divides the upper mixed ...