What is Magma?

What is Magma?

• Magma is liquid rock found beneath Earth's surface, formed when rocks melt.
• It is less dense than solid rock, so it rises to the surface, where it's referred to as lava.
• Magma forms within the interior of Earth, mainly in the crust and upper mantle, due to heat and radioactive decay.
• It can vary in composition, containing dissolved gases like carbon dioxide and hydrogen sulfide.

Formation of Magma

• Magma forms through decompression of rising heat and material from mantle plumes or convection currents.
• Subduction of plate material colliding with another also creates the circumstances for solid rock to melt.
• Mantle plumes rise over long geological timeframes, eventually reaching the base of the lithosphere, where they spread out and melt.
• Decrease in pressure as mantle plume and convection current material rises allows for particles to spread out, melt, and form magma.

Characteristics of Magma

• Temperature range: 1060-1600°C (besides rare carbonatite magmas at 490°C).
• Viscosity and resistance to flow vary depending on the type of magma.
• Some magmas are more viscous, while others flow quickly.

Types of Magma

• Felsic magma: high silica content (>63%), low iron content, highly viscous, and relatively low temperature (800-1200°C).
• Mafic magma: lower silica content (<45%), higher iron content, less viscous, and higher temperature (1100-1600°C).
• Ultramafic magma: very low silica content, high iron content, and high temperature.

Difference between Magma and Lava

• Magma is liquid rock beneath Earth's surface.
• Lava is magma that has reached Earth's surface, where it cools and solidifies into rock.
• Igneous rocks form from the solidification of lava or magma.