The mantle, a layer of Earth between the crust and the outer core, is primarily caused by heat escaping from the Earth's interior. This heat drives mantle convection.
Sources of Heat in the Mantle
The heat driving mantle convection originates from two main sources:
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Residual Heat from Earth's Formation: A significant portion of the heat within the Earth is left over from its formation billions of years ago. This "primordial heat" is gradually being released.
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Radioactive Decay: The decay of unstable isotopes, such as Uranium-238, Thorium-232, and Potassium-40, generates heat within the Earth's interior. These isotopes are distributed throughout the mantle and core.
How Heat Drives the Mantle
The heat from these sources causes:
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Internal Heating: The radioactive decay occurs throughout the mantle's volume, resulting in internal heating.
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Heating at the Core-Mantle Boundary: Heat also rises from the core-mantle boundary, where the core's extreme heat transfers to the lower mantle.
These processes cause the mantle material to heat up. Hotter, less dense mantle material rises, while cooler, denser material sinks. This continuous cycle of rising and sinking is called mantle convection. This convection is a major driving force for plate tectonics and many geological processes on Earth's surface.
