We explain what the Earth's mantle is and its characteristics. Also, its function, composition and the definition of the Earth's core and crust.
What is the earth's mantle?
The earth's mantle is a layer of dense, hot rock located inside the planet Earthbetween the core and the Earth's crust. It has a thickness of 3,000 km and minerals such as silicates predominate.
It is a structure that does not have a uniform compositionbut it is mainly made up of materials that contain silica, oxygen, magnesium, iron, aluminum and other metals.
The temperatures in this area of the Earth vary depending on how close or far it is from the core. So, The area closest to the core can reach a temperature of around 3500 °Cwhile the areas furthest from the core can have temperatures around 600 °C.
The earth's mantle It has two defined layers: the upper mantle and the lower mantle. The upper mantle has a greater viscosity than the lower mantle, its interior moves very slowly and is responsible for the movement of tectonic plates.
See also: Volcanoes
Function of the earth's mantle
The Earth's mantle constitutes more than 80% of the volume of planet Earth and Its main function is to be thermal insulator and refractory of the earth's surface.
The movements of the upper mantle are constant and are produced by convective currents that move the Earth's tectonic plates. The movement of tectonic plates is vital for the geological development of the planet and the survival of the living beings that inhabit it, since it generates new surfaces.
Magma expelled from the mantle, in processes such as volcanism, forms a new crust where tectonic plates separate. These are processes that intervene in the carbon cycle, which is essential to regulate the Earth's temperature.
Ground command characteristics
Some of the main characteristics of the Earth's mantle are:
- It is the largest layer that makes up the Earth and occupies more than 80% of the planet.
- It is the layer that is between the surface or earth's crust and the core.
- It is made up of the lower mantle and the upper mantle.
- It has temperatures that exceed 600 °C.
- It extends from 8 km in oceanic areas, 30 km in continental areas and 70 km in mountainous areas.
- It is mainly made up of elements containing silicon, oxygen, magnesium and iron.
- It is made up of elements in a solid or viscous state.
- It is responsible for the movement of tectonic plates, due to the convection currents that occur within them.
- Its study is based on the materials that emerge on the Earth's surface as a result of phenomena such as volcanic activity and orogeny and with the study of seismic waves.
Composition and structure of the Earth's mantle
The Earth's mantle differs from the core and the Earth's crust by its composition. Although the composition of the mantle is not uniform, It is mainly made up of silicatesthat is, materials composed of oxygen and silicon that may also contain iron, calcium and aluminum.
There are two distinct layers of the Earth's mantle: the lower mantle and the upper mantle. Between both layers a particular acceleration of seismic waves occurs and its main characteristics are:
- Upper mantle. It begins at the Mohorovicic discontinuity, which is the transition zone between the Earth's crust and mantle, and is divided into two layers: the lithosphere and the asthenosphere. The upper mantle is a mostly solid structure made up of peridotite and chemical components such as silicon, oxygen, magnesium and iron. In the asthenosphere, compounds can flow, allowing the movement of tectonic plates. Temperatures in the upper mantle range from 200 to 900 °C and it is a structure that has a thickness of more than 600 km.
- inner mantle. It begins in the transition zone after the upper mantle and extends to the Gutenberg discontinuity. It has a thickness ranging from 700 km to 2900 km and has higher temperature and pressure than the upper mantle and the transition zone. It is a solid layer formed by elements composed of silicon and magnesium, such as the mineral perovskite. Most of the evidence known about this layer arises from investigations of the magma that emerges from the Earth after volcanic activity.
The core and crust of the earth
In addition to the Earth's mantle, planet Earth is made up of two other structures:
- the earth's crust. It is a thin layer that can range from 5 to 50 km thick, it is the outermost layer of the Earth and living beings live there. It is mainly made up of oxygen, silica and aluminum. The boundary between the crust and the mantle is named after its discoverer, the geophysicist, Andrija Mohorovicic, and its function is to separate materials of higher density (iron silicate, magnesium) from those of lower density (calcium, potassium or sodium).
- The core. It is a sphere with a radius of 3,400 km that constitutes the innermost part of the Earth and is composed mainly of iron. The transition zone between the core and the Earth's mantle is known as the Gutenberg discontinuity. Below this discontinuity is where the Earth's magnetic field originates. The core is divided into:
- Outer core. It is located between the mantle and the inner core and is in a liquid state.
- Inner core. It is the innermost layer of the Earth and is in a solid state.
References:
- “Plates Tectonics” in National Geographic.
- “Why are tectonic plates and their movements essential for life?” on BBC.
- “Mantle” in National Geographic.
- “What is seismology?” at National Geographic Institute.
- “The composition and structure of Earth” in Lumen Learning.
