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] As the crystal fraction makes up less than half of the volume, there is no rigid large-scale three-dimensional network as in solids.[2] As such, their rheological behavior mirrors that of absolute liquids.
Within a single crystal mush, there is grading to a higher solid fraction towards the margins of the pluton, while the liquid fraction increases towards the uppermost portions, forming a liquid lens at the top.[1] Furthermore, depending on depth of placement crystal mushes are likely to contain a larger portion of crystals at greater depth in the crust than at shallower depth, as melting occurs from the adiabatic decompression of the magma as it rises, this is particularly the case for mid-ocean ridges.[3]
Seismic investigation offers strong evidence for the existence of crystal mushes rather than fully liquid magmatic bodies.[1]
Crystal mushes can have a wide range of mineral and chemical compositions, from mafic (SiO2-poor, MgO-rich) to felsic (SiO2-rich, MgO-poor).
- ^ a b c Cooper, Kari M. (February 2017). "What Does a Magma Reservoir Look Like? The 'Crystal's-Eye' View". Elements. 13: 23–28. doi:10.2113/gselements.13.1.23.
- ^ Winter, John D. (2014). Principles of Igneous and Metamorphic Petrology. Essex: Pearson Education Limited. pp. 213, 217. ISBN 978-1-292-02153-9.
- ^ Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of Igneous and Metamorphic Petrology. Cambridge: Cambridge University Press. p. 16. ISBN 978-0-521-88006-0.
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