Temperature of Earth's mantle
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Earth's Mantle Temperature Profile: Key Depths and Gradients
Upper Mantle Temperatures and Discontinuities
Recent studies estimate the temperature at the 410-km discontinuity, a key boundary in the upper mantle, to be around 1805–1839 K (about 1532–1566°C) 15. At a shallower depth of 50 km, temperatures are estimated at 1617–1646 K (1344–1373°C) 15. These values are determined by analyzing mineral phase transitions, particularly the olivine-wadsleyite transition, and using adiabatic temperature gradients based on the properties of major mantle minerals 15.
Transition Zone and Lower Mantle Temperatures
Just above and below the 660-km discontinuity, which marks the boundary between the upper and lower mantle, temperatures are estimated at 1959–1994 K (1686–1721°C) and 1925–1960 K (1652–1687°C), respectively 15. These estimates are consistent with the adiabatic temperature profile, which suggests that the temperature gradient in the deeper mantle closely follows the adiabatic gradient, supporting the idea of solid-state convection as the main heat transport mechanism 35.
Deep Lower Mantle and Core-Mantle Boundary (CMB) Temperatures
At a depth of 2800 km, near the base of the mantle, temperatures are estimated to be 2530–2587 K (2257–2314°C) 15. The temperature at the core-mantle boundary is a subject of ongoing research, with estimates ranging from about 3570 K (3297°C) to 4000 K (3727°C) 26710. Some studies suggest the CMB temperature could be as low as 3570 ± 200 K, based on experimental measurements of the melting point of mantle rocks, while others estimate it to be closer to 3800–4000 K, using seismological and mineral physics modeling 6710. These values indicate a sharp thermal gradient of about 1500 K in the lowermost mantle 267.
Temperature Variability and Mantle Melting
The mantle is not uniformly hot; lateral temperature variations of 200–300 K are observed, especially near the core-mantle boundary, which helps explain seismic velocity differences in the D'' layer 710. The solidus (melting point) of the mantle at the core-mantle boundary is estimated to be around 3570 K, providing an upper limit for the temperature in this region . Most of the mantle, especially at depths greater than a few hundred kilometers, is close to its solidus temperature, which regulates the thermal structure and dynamics of the Earth's interior 36.
Long-Term Mantle Cooling
Over geological time, the Earth's mantle has cooled by about 150°C since 2.5 billion years ago, with the difference between the hottest and coolest regions of the mantle remaining relatively constant at around 170°C . This gradual cooling is linked to the evolution of plate tectonics and the stabilization of mantle temperatures .
Conclusion
The temperature of Earth's mantle increases with depth, from about 1600 K near the top to 2500–2600 K near the base, with the core-mantle boundary reaching 3570–4000 K. These temperatures are determined by mineral phase transitions, experimental melting data, and seismic observations. The mantle's temperature profile is crucial for understanding mantle convection, the generation of magmas, and the thermal evolution of the planet 123567910.
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