The molten rocks present in the interior of the earth’s mantle is known as magma. The interior temperature of the earth is very high, which melts the rocks present in the mantle. The molten rocks when extrude through the vent of the volcano are known as lava. In other words lava before ejection is known as magma.
Like solid rocks, magma is a mixture of minerals and rocks, However, a small amount of gases and liquids is mixed with the magma.
Types of Magma:
- Basaltic Magma: Most basaltic magma is believed to originate in partially molten asthenosphere at depths exceeding 200 kilometers. Since magma is lighter is lighter than the surrounding rocks, it has a tendency to rise.
- Andesitic magma: Andesitic magma, which is of intermediate composition is believed to originate mainly by the process of differentiation of basaltic magma. However, the close association of andesitic magma with the subduction zone indicates that it may have formed due to melting of the lithosphere. Lithosphere contains layers of sediments over basalt. It can yield a magma of andesitic composition on partial melting.The volcanic Andes Mountains of South America are thought to ha ve formed in this way.
- Rhyolitic Magma: Rhyolitic lavas erupt only from volcanoes located on continental crust. This magma is believed to have formed due to remelting of the continental crust.