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Metamorphism

Current Research In Metamorphism

Current research in the field of metamorphism ranges from studies of the chemical composition of single crystals within metamorphic rocks (garnet, for example) to the mysteries of metamorphic rocks that form at extremely high pressure, presumably deep within the Earth, and now exist at Earth's surface without changes in the minerals in the rocks as the pressure decreased during uplift to the surface. The effects of fluids on metamorphism continue to attract the attention of researchers.

Studies of the ratios of unstable isotopes (for example, uranium, rubidium, strontium, and argon) allow scientists to determine the times at which rocks metamorphosed. Such data are valuable in studies of regional metamorphism, particularly in areas that have experienced multiple episodes of metamorphism.

Economically important metamorphic minerals such as serpentine can affect health. In the past few years, asbestos removal has had significant impact on the cost of operating schools and other public buildings. In the confusion over illness associated with asbestos made from the amphibole mineral crocidolite, citizens demanded the removal of all asbestos, unaware that a less-hazardous form of asbestos, the serpentine mineral chrysotile, also was removed at great expense.

Research in the field of metamorphism continues to include traditional geological activities such as preparing maps of surface exposures of metamorphic rocks from field studies, observing thin slices of metamorphic rocks using microscopes, and assessing the time, temperature, and pressure at which metamorphism occurs. New technology, particularly lasers and x-ray tomography, allow scientists to examine rocks and single crystals in sufficient detail to understand how crystals grow during metamorphism and at what temperatures and pressures they grow.


Resources

Periodicals

Abelson, Phillip H. "The Asbestos Removal Fiasco." Science 247 (1990): 1017.

Lang, Helen M. "Metamorphic Petrology." Geotimes 40 (1995): 44-45.


Gretchen M. Gillis

KEY TERMS

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Diagenesis

—Compaction, cementation, and other processes that transform sediments into sedimentary rock at low temperatures.

Intrusion

—Movement of melted rock into solid rock. The heat from the melted material can cause contact metamorphism of the solid rock.

Isotopes

—Two molecules in which the number of atoms and the types of atoms are identical, but their arrangement in space is different, resulting in different chemical and physical properties. Uranium has three naturally occurring isotopes, uranium-238, uranium-235, and uranium-234.

Metamorphic facies

—A group of metamorphic minerals typically found together. Different metamorphic facies form at different temperatures and pressures.

Mineral

—A naturally occurring substance with a distinct chemical composition and structure. Quartz, magnetite, calcite, and garnet are minerals.

Regional metamorphism

—Widespread change in temperature and pressure that alters rock, usually associated with tectonic events.

Rock

—A naturally occurring solid mixture of minerals.

Tectonic event

—Episode of movement or deformation of the large plates of oceanic and continental crust that cover Earth. Mountain building and regional metamorphism can result from tectonic events.

Additional topics

Science EncyclopediaScience & Philosophy: Mathematics to Methanal trimerMetamorphism - Types Of Metamorphism, Current Research In Metamorphism