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Structure of Earth. The mesosphere is labeled as Stiffer mantle in this diagram.. The lower mantle, historically also known as the mesosphere, represents approximately 56% of Earth's total volume, and is the region from 660 to 2900 km below Earth's surface; between the transition zone and the outer core. [1]
The source of heat that drives this motion is the decay of radioactive isotopes in Earth's crust and mantle combined with the initial heat from the planet's formation [27] (from the potential energy released by collapsing a large amount of matter into a gravity well, and the kinetic energy of accreted matter). Due to increasing pressure deeper ...
While it seems to be generated mostly by fluid and electric currents in the outer core, those currents are strongly affected by the presence of the solid inner core and by the heat that flows out of it. (Although made of iron, the core is not ferromagnetic, due to being above the Curie temperature.) [citation needed]
Mantle convection is the result of a thermal gradient: the lower mantle is hotter than the upper mantle, and is therefore less dense. This sets up two primary types of instabilities. In the first type, plumes rise from the lower mantle, and corresponding unstable regions of lithosphere drip back into the mantle.
The remaining heat flow at the surface would be due to basal heating of the crust from mantle convection. Heat fluxes are negatively correlated with rock age, [1] with the highest heat fluxes from the youngest rock at mid-ocean ridge spreading centers (zones of mantle upwelling), as observed in the global map of Earth heat flow. [1]
Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. [132] Earth's inner core may be rotating at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year, although both somewhat higher and much lower rates have also been proposed. [ 133 ]
Recently it has been proposed that a higher core cooling rate and lower mantle cooling rate can resolve the paradox in part. [6] [7] [8] However, the paradox remains unresolved. Also, recent geochemical experiments [9] have led to the proposal that radiogenic heat in the core is larger than previously thought. This revision, if true, would also ...
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.