Magma of partial melting of the mantle, komatiite and picrite are produced. Magma develops within the mantle or crust where the temperature and pressure conditions favor the molten state. After its formation, magma buoyantly rises toward the Earth's surface. As it migrates through the crust, magma may collect and reside in magma chambers (though recent work suggests that magma may be stored in trans-crustal crystal-rich mush zones rather than dominantly liquid magma chambers ). Magma can remain in a chamber until it cools and crystallizes forming igneous rock, it erupts as a volcano, or moves into another magma chamber.There are two
Calc-alkaline magma series to increase as the melt is depleted of iron-poor crystals. (Magnesium-rich olivine solidifies at much higher temperatures than iron-rich olivine.) However, a calc-alkaline magma is oxidized enough to (simultaneously) precipitate significant amounts of the iron oxide magnetite, causing the iron content of the magma to remain more steady as it cools than with a tholeiitic magma. The difference between these two magma series can be seen on an AFM diagram, a ternary diagram showing the relative proportions of the oxides of NaO + KO (A), FeO + FeO (F), and MgO (M). As magmas cool, they precipitate out significantly more