Asthenosphere

The asthenosphere is the upper zone of our terrestrial mantle. Located below the lithosphere , approximately 30 to 130 kilometers deep. It is formed or composed of materials in solid and semi-molten state that allow continental drift or the phenomenon caused by the masses of the continents when moving and isostasy. On it tectonic plates are mobilized. This is the region that has the highest viscosity rate and is mechanically very weak relative to the upper layer of the Earth. The asthenosphere is responsible for collecting the heat from the mesosphere and projecting it towards the lithosphere through a convection system, which can be compared to the boiling process of water.

Characteristics of the asthenosphere

The asthenosphere is composed of semi-molten and solid materials at the same time. Above it floats the lithosphere , which is a rigid layer that is composed of the outer part of the mantle and the earth’s crust, thus allowing the movement of the tectonic plates . Another characteristic of the asthenosphere is that it is responsible for promoting the renewal and expansion of the ocean floor . This is because in its composition we find a very important component called basalt , which is an igneous rock that, through an extrusion process, flows through the ocean ridges. It is a part of the upper mantle of the earth and is located just below the lithosphere, which is directly involved with the movement of tectonic plates and isostatic adjustment processes . Although it is a very hot layer, the pressure that exists in it makes it stay like plastic and its density is relatively very low. Earth’s seismic waves pass through it as it is also a low-speed zone. Due to their conditions in terms of temperature and pressure in the asthenosphere, rocks become ductile and move slowly, measuring thousands of kilometers. The radiating heat flows into the earth.

Composition of the asthenosphere

The asthenosphere is made up of rock material. It is made up of iron and magnesium silicates . This chemical composition is almost identical to that of the lower layer of the earth or the mesosphere. In contrast, lithospheric rocks contain more silica , but less aluminum, sodium, and potassium. It is then basically composed of sedimentary rocks , ferromagnetic minerals, magmatic material, radioactive materials and metamorphic rocks .

Function

One of the important functions of the asthenosphere occurs within it. Within it, a phenomenon called convection currents occurs . This means that the materials that are in the lower areas get hotter, and when they heat up, they tend to rise towards the higher areas of the asthenosphere. In the same way, the materials in the higher areas are cooled, and for this reason, these materials will go down. This causes that the materials are in continuous movement, causing an important effect in the movement of the tectonic plates . When the continental plates begin to move, as a consequence of the convection currents of the asthenosphere, geological phenomena such as thetectonic faults , or displacements between masses of the earth’s crust, or earthquakes could even occur (when the friction or collision of two plates is strong). Another important function is that it contains the magma that volcanoes expel when they erupt.

Importance of the asthenosphere

The asthenosphere is a layer of great geological importance for the Earth’s mantle. It is responsible for the creation of new crust on the earth, which means that new earth will be produced. This occurs in ocean ridges, where convection pushes the asthenosphere to the surface. Its importance also lies in the tectonic plates that are located in it since it collaborates with the movement of the continental masses with respect to each other, due to plate tectonics. The convection currents that originate in this layer are of the utmost importance since they are what define the different movements of the plates. It is also responsible for the creation of new crust on earth.