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During cooling, crystals will form from the melt. Thus, the crystal/melt ratio increases, generating a magma, a crystal-mush, and finally a cumulate rock. A crystal mush is magma that contains a significant amount of crystals (up to 50% of the volume) suspended in the liquid phase (melt). [1]
For instance, a magma of gabbroic composition can produce a residual melt of granitic composition if early formed crystals are separated from the magma. [92] Gabbro may have a liquidus temperature near 1,200 °C, [ 93 ] and the derivative granite-composition melt may have a liquidus temperature as low as about 700 °C. [ 94 ]
While cooling, the magma evolves in composition because different minerals crystallize from the melt. 1: olivine crystallizes; 2: olivine and pyroxene crystallize; 3: pyroxene and plagioclase crystallize; 4: plagioclase crystallizes. At the bottom of the magma reservoir, a cumulate rock forms.
At the bottom of the magma reservoir, a cumulate rock forms. Cumulate rocks are the typical product of precipitation of solid crystals from a fractionating magma chamber. These accumulations typically occur on the floor of the magma chamber, although they are possible on the roofs if anorthite plagioclase is able to float free of a denser mafic ...
Assimilation can be broadly defined as a process where a mass of magma wholly or partially homogenizes with materials derived from the wall rock of the magma body. [1] Assimilation is a popular mechanism to partly explain the felsification of ultramafic and mafic magmas as they rise through the crust: a hot primitive melt intruding into a ...
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks.It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of magma or lava.
These rocks were repeatedly recycled by fractional melting, fractional crystallization and separation of magmas that refuse to mix. An example of such a process is Bowen's reaction series. [1] One of the few sources of direct information on mineralogy in this stage is mineral inclusions in zircon crystals, which date as far back as 4.4 Ga.
Intrusion of a felsic to intermediate magma body rich in volatiles. Contact metamorphism and minor metasomatism, skarn formation, occurs in favorable locations. [26] Continued crystallization of the magma and widespread release of volatiles as a hydrothermal fluid which causes widespread skarn formation and localized brecciation. [26]