Mantle

Mantle is a term used in various fields of study to refer to a layer lying below the surface of an object. In the context of Earth science, the mantle is the layer of the Earth that lies between the crust and the core. It is composed primarily of silicate rocks and is subdivided into two main parts: the upper mantle and the lower mantle. The boundary separating these regions is called the Mohorovičić discontinuity (Moho).

The mantle plays a crucial role in the tectonic and volcanic activity of the Earth. It is also the source of magma that feeds volcanoes. The mantle's temperature and pressure conditions enable the occurrence of certain types of chemical reactions that cannot occur under the conditions found at the Earth's surface.

Composition and Structure

The Earth's mantle is composed primarily of silicate rocks rich in magnesium and iron. The upper mantle, which extends from the Moho to a depth of about 410 kilometers, is composed mainly of peridotite, a rock that is dense and greenish in color. The lower mantle, which extends from a depth of 410 kilometers to the core-mantle boundary, is composed of silicate minerals that are stable under the high pressures and temperatures found at these depths.

The mantle is not a uniform layer. It is subdivided into several layers based on seismic evidence. The uppermost part of the mantle and the overlying crust form the lithosphere, a rigid layer that is broken into tectonic plates. Below the lithosphere is the asthenosphere, a region of the mantle that is partially molten and can flow like a liquid.

Role in Plate Tectonics and Volcanic Activity

The mantle plays a crucial role in the tectonic activity of the Earth. The convection currents in the mantle drive the movement of the tectonic plates. When these plates move, they can cause earthquakes and volcanic activity.

The mantle is also the source of magma that feeds volcanoes. When a tectonic plate is forced down into the mantle at a subduction zone, it heats up and partially melts. This melted rock can then rise to the surface and erupt as a volcano.

See Also

• Core (geology)
• Crust (geology)
• Plate tectonics
• Volcano

References

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