Temperature of earth's layers
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Temperature of Earth's Layers
Understanding the temperature distribution within the Earth's layers is crucial for comprehending various geological and geophysical processes. This article synthesizes findings from multiple research studies to provide a comprehensive overview of the temperature profiles across different layers of the Earth.
Surface Layers Temperature
Temperature Monitoring in Perm
Studies conducted in Perm, Russia, have provided detailed insights into the temperature variations in the surface layers of the Earth. Monitoring at two sites with different geological conditions—clay soils in a dense urban area and sandy soils in an unfinished part of the city—revealed significant findings. At the first site, the temperature at a depth of 19 meters ranged from +12°C to 10°C, while at the second site, the temperature remained constant at +6-7°C down to a depth of 37 meters. Seasonal temperature fluctuations were observed up to a depth of 10 meters, influenced by the outside air temperature 12.
Crust and Mantle Temperature
Mohorovičić Discontinuity
The Mohorovičić Discontinuity, or Moho, marks the boundary between the Earth's crust and mantle. This layer, located 30-50 km below the continents and about 10 km below ocean basins, exhibits temperatures ranging from 500°C to 600°C at the base of the continental crust and 150°C to 200°C in the sub-oceanic regions. The Moho is also characterized by high compressive stress and a density of about 4.0 g/cm³ .
Mantle Temperature Profile
The mantle's temperature profile is complex, with significant variations at different depths. The temperature at the core-mantle boundary (CMB) is estimated to be around 3500-4500 K, with a thermal boundary layer at the base of the mantle showing a temperature decrease of approximately 880 K across a thickness of 180 km. The upper mantle exhibits a superadiabatic temperature drop of up to 600 K, while the lower mantle shows drops of around 650 K at both the top and bottom layers 458.
Core Temperature
Inner Core and Core-Mantle Boundary
The temperature at the inner core boundary (ICB) is estimated to be around 5000 K, with an adiabatic extrapolation to the CMB giving a temperature of approximately 3800 K. The initial temperature of the Earth's core, based on models of mantle convection and core growth, is estimated to have been around 4200 K, leading to a present-day temperature of about 3820 K at the CMB 45.
Heat Flow and Thermal Regime
The Earth's thermal regime is influenced by heat flow from the core to the mantle, estimated at 7.5×10¹² W. The thermal relaxation times for the upper and lower mantle are approximately 10⁸ years and 1.5×10⁹ years, respectively. These thermal boundary layers are crucial for understanding the dynamics of mantle convection and the geomagnetic properties of the Earth's core 48.
Conclusion
The temperature distribution within the Earth's layers varies significantly, from the surface layers influenced by seasonal changes to the high temperatures at the core-mantle boundary. Understanding these temperature profiles is essential for studying geological processes, mantle convection, and the Earth's magnetic field. The synthesis of research findings provides a clearer picture of the thermal state of the Earth's interior, highlighting the complexity and variability of temperatures across different layers.
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