Magma

Magma is a molten or semi-molten natural material from within the Earth's crust that forms igneous rock upon cooling. Magma is generated by the internal heat of the planet and is capable of intrusion into the crust, extrusion onto the surface as lava, and explosive eruptions, to form volcanoes.

Formation

Magma is produced when the Earth's mantle or crust melts. This can occur because of one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface.

Types

There are three major types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition. All three types of magma can be found at volcanoes and tectonic settings such as subduction zones and mid-ocean ridges.

Behavior

Magma behaves like a liquid and thus responds to pressure, temperature, and composition changes. The viscosity of magma is primarily determined by its temperature, composition, and crystal content.

Role in the Earth's crust and mantle

Magma plays a key role in the formation of the Earth's crust and mantle. The cooling of magma leads to the formation of igneous rock, which makes up a significant portion of the Earth's crust.

See also

• Lava
• Volcano
• Igneous rock
• Earth's crust
• Earth's mantle

Magma Resources
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