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METAMORPHIC ROCKS
Lesson 1 - Page 7

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Contact metamorphism does not affect as large an area as regional metamorphism. It is associated with areas around a magma chamber as well as other smaller igneous structures like dikes or sills. Contact metamorphism zones can be a few centimeters to several kilometers, especially around large plutons. The rocks that are formed will depend on the country rock that the intrusion invades.

There are other conditions that form metamorphic rocks. Burial metamorphism is a special type of low grade metamorphism with low temperatures and pressures. Cataclastic metamorphism only occurs along fault zones, usually associated with subduction or transform zones. Conditions include high pressures under lower temperatures.

The formation of many metamorphic rocks is still debated. Observation of extreme pressure and temperature inside the crust and upper mantle and how they affect rocks is difficult. Some rocks are only slightly metamorphosed and given the term meta-igneous or meta-sedimentary.

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