Contact Metamorphic Facies
Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay
Most of the interesting changes in contact metamorphism happen between 500 and 600 C. It is unusual for rocks to get much hotter even in contact with mafic magmas.
 | Ca 520. Hydrous phases dominate. Epidote forms. Pyrophyllite may be present but andalusite is also possible. |
Ca. 550 C
 | Andalusite is the aluminosilicate. Talc is replaced by amphiboles. On the calcic side, diopside and grossularite form. Anorthite forms instead of epidote. Cordierite forms. |
Ca. 570 C
 | All the amphiboles break down and are replaced by pyroxenes. Muscovite breaks down. The only hydrous phase left is biotite. |
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Created 25 November 2009, Last Update