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Metamorphism

January 20, 2023

For other uses, see Metamorphism (disambiguation).

Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of 150 to 200 °C (300 to 400 °F), and often also at elevated pressure or in the presence of chemically active fluids, but the rock remains mostly solid during the transformation.[1] Metamorphism is distinct from weathering or diagenesis, which are changes that take place at or just beneath Earth's surface.[2]

Schematic representation of a metamorphic reaction. Abbreviations of minerals: act = actinolite; chl = chlorite; ep = epidote; gt = garnet; hbl = hornblende; plag = plagioclase. Two minerals represented in the figure do not participate in the reaction, they can be quartz and K-feldspar. This reaction takes place in nature when a mafic rock goes from amphibolite facies to greenschist facies.
A cross-polarized thin section image of a garnet-mica-schist from Salangen, Norway showing the strong strain fabric of schists. The black (isotropic) crystal is garnet, the pink-orange-yellow colored strands are muscovite mica, and the brown crystals are biotite mica. The grey and white crystals are quartz and (limited) feldspar.

Various forms of metamorphism exist, including regional, contact, hydrothermal, shock, and dynamic metamorphism. These differ in the characteristic temperatures, pressures, and rate at which they take place and in the extent to which reactive fluids are involved. Metamorphism occurring at increasing pressure and temperature conditions is known as prograde metamorphism, while decreasing temperature and pressure characterize retrograde metamorphism.

Metamorphic petrology is the study of metamorphism. Metamorphic petrologists rely heavily on statistical mechanics and experimental petrology to understand metamorphic processes.

Metamorphic processes

 
(Left) Randomly-orientated grains in a rock before metamorphism. (Right) Grains align orthogonal to the applied stress if a rock is subjected to stress during metamorphism

Metamorphism is the set of processes by which existing rock is transformed physically or chemically at elevated temperature, without actually melting to any great degree. The importance of heating in the formation of metamorphic rock was first recognized by the pioneering Scottish naturalist, James Hutton, who is often described as the father of modern geology. Hutton wrote in 1795 that some rock beds of the Scottish Highlands had originally been sedimentary rock, but had been transformed by great heat.[3]

Hutton also speculated that pressure was important in metamorphism. This hypothesis was tested by his friend, James Hall, who sealed chalk into a makeshift pressure vessel constructed from a cannon barrel and heated it in an iron foundry furnace. Hall found that this produced a material strongly resembling marble, rather than the usual quicklime produced by heating of chalk in the open air. French geologists subsequently added metasomatism, the circulation of fluids through buried rock, to the list of processes that help bring about metamorphism. However, metamorphism can take place without metasomatism (isochemical metamorphism) or at depths of just a few hundred meters where pressures are relatively low (for example, in contact metamorphism).[3]

Rock can be transformed without melting because heat causes atomic bonds to break, freeing the atoms to move and form new bonds with other atoms. Pore fluid present between mineral grains is an important medium through which atoms are exchanged.[4] This permits recrystallization of existing minerals or crystallization of new minerals with different crystalline structures or chemical compositions (neocrystallization).[1] The transformation converts the minerals in the protolith into forms that are more stable (closer to chemical equilibrium) under the conditions of pressure and temperature at which metamorphism takes place.[5][6]

Metamorphism is generally regarded to begin at temperatures of 100 to 200 °C (212 to 392 °F). This excludes diagenetic changes due to compaction and lithification, which result in the formation of sedimentary rocks.[7] The upper boundary of metamorphic conditions lies at the solidus of the rock, which is the temperature at which the rock begins to melt. At this point, the process becomes an igneous process.[8] The solidus temperature depends on the composition of the rock, the pressure, and whether the rock is saturated with water. Typical solidus temperatures range from 650 °C (1,202 °F) for wet granite at a few hundred megapascals (Mpa) of pressure[9] to about 1,080 °C (1,980 °F) for wet basalt at atmospheric pressure.[10] Migmatites are rocks formed at this upper limit, which contains pods and veins of material that has started to melt but has not fully segregated from the refractory residue.[11]

The metamorphic process can occur at almost any pressure, from near surface pressure (for contact metamorphism) to pressures in excess of 16 kbar (1500 Mpa).[12]

Recrystallization

 
Basalt hand sample showing fine texture
 
Amphibolite formed by metamorphism of basalt showing coarse texture

The change in the grain size and orientation in the rock during the process of metamorphism is called recrystallization. For instance, the small calcite crystals in the sedimentary rocks limestone and chalk change into larger crystals in the metamorphic rock marble.[13] In metamorphosed sandstone, recrystallization of the original quartz sand grains results in very compact quartzite, also known as metaquartzite, in which the often larger quartz crystals are interlocked.[14] Both high temperatures and pressures contribute to recrystallization. High temperatures allow the atoms and ions in solid crystals to migrate, thus reorganizing the crystals, while high pressures cause solution of the crystals within the rock at their points of contact (pressure solution) and redeposition in pore space.[15]

During recrystallization, the identity of the mineral does not change, only its texture. Recrystallization generally begins when temperatures reach above half the melting point of the mineral on the Kelvin scale.[16]

Pressure solution begins during diagenesis (the process of lithification of sediments into sedimentary rock) but is completed during early stages of metamorphism. For a sandstone protolith, the dividing line between diagenesis and metamorphism can be placed at the point where strained quartz grains begin to be replaced by new, unstrained, small quartz grains, producing a mortar texture that can be identified in thin sections under a polarizing microscope. With increasing grade of metamorphism, further recrystallization produces foam texture, characterized by polygonal grains meeting at triple junctions, and then porphyroblastic texture, characterized by coarse, irregular grains, including some larger grains (porphyroblasts.)[17]

 
A mylonite (through a petrographic microscope)

Metamorphic rocks are typically more coarsely crystalline than the protolith from which they formed. Atoms in the interior of a crystal are surrounded by a stable arrangement of neighboring atoms. This is partially missing at the surface of the crystal, producing a surface energy that makes the surface thermodynamically unstable. Recrystallization to coarser crystals reduces the surface area and so minimizes the surface energy.[18]

Although grain coarsening is a common result of metamorphism, rock that is intensely deformed may eliminate strain energy by recrystallizing as a fine-grained rock called mylonite. Certain kinds of rock, such as those rich in quartz, carbonate minerals, or olivine, are particularly prone to form mylonites, while feldspar and garnet are resistant to mylonitization.[19]

Phase change

 
 
Phase diagram of Al2SiO5
(nesosilicates)

Phase change metamorphism is the creating of a new mineral with the same chemical formula as a mineral of the protolith. This involves a rearrangement of the atoms in the crystals. An example is provided by the aluminium silicate minerals, kyanite, andalusite, and sillimanite. All three have the identical composition, Al2SiO5. Kyanite is stable at surface conditions. However, at atmospheric pressure, kyanite transforms to andalusite at a temperature of about 190 °C (374 °F). Andalusite, in turn, transforms to sillimanite when the temperature reaches about 800 °C (1,470 °F). At pressures above about 4 kbar (400 Mpa), kyanite transforms directly to sillimanite as the temperature increases.[20] A similar phase change is sometimes seen between calcite and aragonite, with calcite transforming to aragonite at elevated pressure and relatively low temperature.[21]

Neocrystallization

Neocrystallization involves the creation of new mineral crystals different from the protolith. Chemical reactions digest the minerals of the protolith which yields new minerals. This is a very slow process as it can also involve the diffusion of atoms through solid crystals.[22]

An example of a neocrystallization reaction is the reaction of fayalite with plagioclase at elevated pressure and temperature to form garnet. The reaction is:[23]

fayalite3 Fe
2SiO
4 + plagioclaseCaAl
2Si
2O
8 → garnet2 CaFe
2Al
2Si
3O
12

 

 

 

 

(Reaction 1)

Many complex high-temperature reactions may take place between minerals without them melting, and each mineral assemblage produced provides us with a clue as to the temperatures and pressures at the time of metamorphism. These reactions are possible because of rapid diffusion of atoms at elevated temperature. Pore fluid between mineral grains can be an important medium through which atoms are exchanged.[4]

A particularly important group of neocrystallization reactions are those that release volatiles such as water and carbon dioxide. During metamorphism of basalt to eclogite in subduction zones, hydrous minerals break down, producing copious quantities of water.[24] The water rises into the overlying mantle, where it lowers the melting temperature of the mantle rock, generating magma via flux melting.[25] The mantle-derived magmas can ultimately reach the Earth's surface, resulting in volcanic eruptions. The resulting arc volcanoes tend to produce dangerous eruptions, because their high water content makes them extremely explosive.[26]

Examples of dehydration reactions that release water include:[27]

hornblende7Ca2Mg3Al4Si6O22(OH)2 + quartz1010SiO2 → cummingtonite3Mg7Si8O22(OH)2 + anorthite14CaAl2Si2O8 + water4H2O

 

 

 

 

(Reaction 2)

muscovite2KAl2(AlSi3O10)(OH)2 + quartz2SiO2 → sillimanite2Al2SiO5 + potassium feldspar2KAlSi3O8 + water2H2O

 

 

 

 

(Reaction 3)

An example of a decarbonation reaction is:[28]

calciteCaCO3 + quartzSiO2 → wollastoniteCaSiO3 + carbon dioxideCO2

 

 

 

 

(Reaction 4)

Plastic deformation

In plastic deformation pressure is applied to the protolith, which causes it to shear or bend, but not break. In order for this to happen temperatures must be high enough that brittle fractures do not occur, but not so high that diffusion of crystals takes place.[22] As with pressure solution, the early stages of plastic deformation begin during diagenesis.[29]

Types

Regional

Regional metamorphism is a general term for metamorphism that affects entire regions of the Earth's crust.[30] It most often refers to dynamothermal metamorphism, which takes place in orogenic belts (regions where mountain building is taking place),[31] but also includes burial metamorphism, which results simply from rock being buried to great depths below the Earth's surface in a subsiding basin.[32][33]

Dynamothermal

 
A metamorphic rock, deformed during the Variscan orogeny, at Vall de Cardós, Lérida, Spain

To many geologists, regional metamorphism is practically synonymous with dynamothermal metamorphism.[30] This form of metamorphism takes place at convergent plate boundaries, where two continental plates or a continental plate and an island arc collide. The collision zone becomes a belt of mountain formation called an orogeny. The orogenic belt is characterized by thickening of the Earth's crust, during which the deeply buried crustal rock is subjected to high temperatures and pressures and is intensely deformed.[33][34] Subsequent erosion of the mountains exposes the roots of the orogenic belt as extensive outcrops of metamorphic rock,[35] characteristic of mountain chains.[33]

Metamorphic rock formed in these settings tends to shown well-developed foliation.[33] Foliation develops when a rock is being shortened along one axis during metamorphism. This causes crystals of platy minerals, such as mica and chlorite, to become rotated such that their short axes are parallel to the direction of shortening. This results in a banded, or foliated, rock, with the bands showing the colors of the minerals that formed them. Foliated rock often develops planes of cleavage. Slate is an example of a foliated metamorphic rock, originating from shale, and it typically shows well-developed cleavage that allows slate to be split into thin plates.[36]

The type of foliation that develops depends on the metamorphic grade. For instance, starting with a mudstone, the following sequence develops with increasing temperature: The mudstone is first converted to slate, which is a very fine-grained, foliated metamorphic rock, characteristic of very low grade metamorphism. Slate in turn is converted to phyllite, which is fine-grained and found in areas of low grade metamorphism. Schist is medium to coarse-grained and found in areas of medium grade metamorphism. High-grade metamorphism transforms the rock to gneiss, which is coarse to very coarse-grained.[37]

Rocks that were subjected to uniform pressure from all sides, or those that lack minerals with distinctive growth habits, will not be foliated. Marble lacks platy minerals and is generally not foliated, which allows its use as a material for sculpture and architecture.

Collisional orogenies are preceded by subduction of oceanic crust.[38] The conditions within the subducting slab as it plunges toward the mantle in a subduction zone produce their own distinctive regional metamorphic effects, characterized by paired metamorphic belts.[39]

The pioneering work of George Barrow on regional metamorphism in the Scottish Highlands showed that some regional metamorphism produces well-defined, mappable zones of increasing metamorphic grade. This Barrovian metamorphism is the most recognized metamorphic series in the world. However, Barrovian metamorphism is specific to pelitic rock, formed from mudstone or siltstone, and it is not unique even in pelitic rock. A different sequence in the northeast of Scotland defines Buchan metamorphism, which took place at lower pressure than the Barrovian.[40]

Burial

 
Sioux Quartzite, a product of burial metamorphism

Burial metamorphism takes place simply through rock being buried to great depths below the Earth's surface in a subsiding basin.[33] Here the rock subjected to high temperatures and the great pressure caused by the immense weight of the rock layers above. Burial metamorphism tends to produced low-grade metamorphic rock. This shows none of the effects of deformation and folding so characteristic of dynamothermal metamorphism.[41]

Examples of metamorphic rocks formed by burial metamorphism include some of the rocks of the Midcontinent Rift System of North America, such as the Sioux Quartzite,[42] and in the Hamersley Basin of Australia.[43]

Contact (thermal)

 
A metamorphic aureole in the Henry Mountains, Utah. The greyish rock on top is the igneous intrusion, consisting of porphyritic granodiorite from the Henry Mountains laccolith, and the pinkish rock on the bottom is the sedimentary country rock, a siltstone. In between, the metamorphosed siltstone is visible as both the dark layer (~5  cm thick) and the pale layer below it.
 

Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole,[44] the contact aureole, or simply the aureole.[45] Contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained[46][47] and extremely tough.[48]

Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact.[49] The size of the aureole depends on the heat of the intrusion, its size, and the temperature difference with the wall rocks. Dikes generally have small aureoles with minimal metamorphism, extending not more than one or two dike thicknesses into the surrounding rock,[50] whereas the aureoles around batholiths can be up to several kilometers wide.[51][52]

The metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole. This is usually related to the metamorphic temperatures of pelitic or aluminosilicate rocks and the minerals they form. The metamorphic grades of aureoles at shallow depth are albite-epidote hornfels, hornblende hornfels, pyroxene hornfels, and sillimanite hornfels, in increasing order of temperature of formation. However, the albite-epidote hornfels is often not formed, even though it is the lowest temperature grade.[53]

Magmatic fluids coming from the intrusive rock may also take part in the metamorphic reactions. An extensive addition of magmatic fluids can significantly modify the chemistry of the affected rocks. In this case the metamorphism grades into metasomatism. If the intruded rock is rich in carbonate the result is a skarn.[54] Fluorine-rich magmatic waters which leave a cooling granite may often form greisens within and adjacent to the contact of the granite.[55] Metasomatic altered aureoles can localize the deposition of metallic ore minerals and thus are of economic interest.[56][57]

Fenitization, or Na-metasomatism, is a distinctive form of contact metamorphism accompanied by metasomatism. It takes place around intrusions of a rare type of magma called a carbonatite that is highly enriched in carbonates and low in silica. Cooling bodies of carbonatite magma give off highly alkaline fluids rich in sodium as they solidify, and the hot, reactive fluid replaces much of the mineral content in the aureole with sodium-rich minerals.[58]

A special type of contact metamorphism, associated with fossil fuel fires, is known as pyrometamorphism.[59][60]

Hydrothermal

Hydrothermal metamorphism is the result of the interaction of a rock with a high-temperature fluid of variable composition. The difference in composition between an existing rock and the invading fluid triggers a set of metamorphic and metasomatic reactions. The hydrothermal fluid may be magmatic (originate in an intruding magma), circulating groundwater, or ocean water.[33] Convective circulation of hydrothermal fluids in the ocean floor basalts produces extensive hydrothermal metamorphism adjacent to spreading centers and other submarine volcanic areas. The fluids eventually escape through vents on the ocean floor known as black smokers.[61] The patterns of this hydrothermal alteration are used as a guide in the search for deposits of valuable metal ores.[62]

Shock

Main article: Shock metamorphism

Shock metamorphism occurs when an extraterrestrial object (a meteorite for instance) collides with the Earth's surface. Impact metamorphism is, therefore, characterized by ultrahigh pressure conditions and low temperature. The resulting minerals (such as SiO2 polymorphs coesite and stishovite) and textures are characteristic of these conditions.[63]

Dynamic

Dynamic metamorphism is associated with zones of high strain such as fault zones.[33] In these environments, mechanical deformation is more important than chemical reactions in transforming the rock. The minerals present in the rock often do not reflect conditions of chemical equilibrium, and the textures produced by dynamic metamorphism are more significant than the mineral makeup.[64]

There are three deformation mechanisms by which rock is mechanically deformed. These are cataclasis, the deformation of rock via the fracture and rotation of mineral grains;[65] plastic deformation of individual mineral crystals; and movement of individual atoms by diffusive processes.[66] The textures of dynamic metamorphic zones are dependent on the depth at which they were formed, as the temperature and confining pressure determine the deformation mechanisms which predominate.[67]

At the shallowest depths, a fault zone will be filled with various kinds of unconsolidated cataclastic rock, such as fault gouge or fault breccia. At greater depths, these are replaced by consolidated cataclastic rock, such as crush breccia, in which the larger rock fragments are cemented together by calcite or quartz. At depths greater than about 5 kilometers (3.1 mi), cataclasites appear; these are quite hard rocks consist of crushed rock fragments in a flinty matrix, which forms only at elevated temperature. At still greater depths, where temperatures exceed 300 °C (572 °F), plastic deformation takes over, and the fault zone is composed of mylonite. Mylonite is distinguished by its strong foliation, which is absent in most cataclastic rock.[68] It is distinguished from the surrounding rock by its finer grain size.[69]

There is considerable evidence that cataclasites form as much through plastic deformation and recrystallization as brittle fracture of grains, and that the rock may never fully lose cohesion during the process. Different minerals become ductile at different temperatures, with quartz being among the first to become ductile, and sheared rock composed of different minerals may simultaneously show both plastic deformation and brittle fracture.[70]

The strain rate also affects the way in which rocks deform. Ductile deformation is more likely at low strain rates (less than 10−14 sec−1) in the middle and lower crust, but high strain rates can cause brittle deformation. At the highest strain rates, the rock may be so strongly heated that it briefly melts, forming a glassy rock called pseudotachylite.[71][72] Pseudotachylites seem to be restricted to dry rock, such as granulite.[73]

Classification of metamorphic rocks

Main article: Metamorphic rock § Classification

Metamorphic rocks are classified by their protolith, if this can be determined from the properties of the rock itself. For example, if examination of a metamorphic rock shows that its protolith was basalt, it will be described as a metabasalt. When the protolith cannot be determined, the rock is classified by its mineral composition or its degree of foliation.[74][75][76]

Metamorphic grades

Metamorphic grade is an informal indication of the amount or degree of metamorphism.[77]

In the Barrovian sequence (described by George Barrow in zones of progressive metamorphism in Scotland), metamorphic grades are also classified by mineral assemblage based on the appearance of key minerals in rocks of pelitic (shaly, aluminous) origin:

Low grade ------------------- Intermediate --------------------- High grade

Greenschist ------------- Amphibolite ----------------------- Granulite
Slate --- Phyllite ---------- Schist ---------------------- Gneiss --- Migmatite
Chlorite zone
Biotite zone
Garnet zone
Staurolite zone
Kyanite zone
Sillimanite zone

A more complete indication of this intensity or degree is provided by the concept of metamorphic facies.[77]

Metamorphic facies

Main article: Metamorphic facies

Metamorphic facies are recognizable terranes or zones with an assemblage of key minerals that were in equilibrium under specific range of temperature and pressure during a metamorphic event. The facies are named after the metamorphic rock formed under those facies conditions from basalt.[78]

The particular mineral assemblage is somewhat dependent on the composition of that protolith, so that (for example) the amphibolite facies of a marble will not be identical with the amphibolite facies of a pellite. However, the facies are defined such that metamorphic rock with as broad a range of compositions as is practical can be assigned to a particular facies. The present definition of metamorphic facies is largely based on the work of the Finnish geologist, Pentti Eskola in 1921, with refinements based on subsequent experimental work. Eskola drew upon the zonal schemes, based on index minerals, that were pioneered by the British geologist, George Barrow.[12]

The metamorphic facies is not usually considered when classifying metamorphic rock based on protolith, mineral mode, or texture. However, a few metamorphic facies produce rock of such distinctive character that the facies name is used for the rock when more precise classification is not possible. The chief examples are amphibolite and eclogite. The British Geological Survey strongly discourages use of granulite as a classification for rock metamorphosed to the granulite facies. Instead, such rock will often be classified as a granofels.[75] However, this is not universally accepted.[76]

 
Temperatures and pressures of metamorphic facies
Temperature Pressure Facies
Low Low Zeolite
Lower Moderate Lower Moderate Prehnite-Pumpellyite
Moderate to High Low Hornfels
Low to Moderate Moderate to High Blueschist
Moderate → High Moderate Greenschist→Amphibolite→Granulite
Moderate to High High Eclogite

See diagram for more detail.

Prograde and retrograde

Metamorphism is further divided into prograde and retrograde metamorphism. Prograde metamorphism involves the change of mineral assemblages (paragenesis) with increasing temperature and (usually) pressure conditions. These are solid state dehydration reactions, and involve the loss of volatiles such as water or carbon dioxide. Prograde metamorphism results in rock characteristic of the maximum pressure and temperature experienced. Metamorphic rocks usually do not undergo further change when they are brought back to the surface.[79]

Retrograde metamorphism involves the reconstitution of a rock via revolatisation under decreasing temperatures (and usually pressures), allowing the mineral assemblages formed in prograde metamorphism to revert to those more stable at less extreme conditions. This is a relatively uncommon process, because volatiles produced during prograde metamorphism usually migrate out of the rock and are not available to recombine with the rock during cooling. Localized retrograde metamorphism can take place when fractures in the rock provide a pathway for groundwater to enter the cooling rock.[79]

Equilibrium mineral assemblages

 
Petrogenetic grid showing aluminium silicate-muscovite-quartz-K feldspar phase boundaries
 
ACF compatibility diagrams (aluminium-calcium-iron) showing phase equilibria in metamorphic mafic rocks at different P-T circumstances (metamorphic facies). Dots represent mineral phases, thin grey lines are equilibria between two phases. Mineral abbreviations: act = actinolite; cc = calcite; chl = chlorite; di = diopside; ep = epidote; glau = glaucophane; gt = garnet; hbl = hornblende; ky = kyanite; law = lawsonite; plag = plagioclase; om = omphacite; opx = orthopyroxene; zo = zoisite

Metamorphic processes act to bring the protolith closer to thermodynamic equilibrium, which is its state of maximum stability. For example, shear stress (nonhydrodynamic stress) is incompatible with thermodynamic equilibrium, so sheared rock will tend to deform in ways that relieve the shear stress.[80] The most stable assemblage of minerals for a rock of a given composition is that which minimizes the Gibbs free energy[81]

 

where:

In other words, a metamorphic reaction will take place only if it lowers the total Gibbs free energy of the protolith. Recrystallization to coarser crystals lowers the Gibbs free energy by reducing surface energy,[18] while phase changes and neocrystallization reduce the bulk Gibbs free energy. A reaction will begin at the temperature and pressure where the Gibbs free energy of the reagents becomes greater than that of the products.[82]

A mineral phase will generally be more stable if it has a lower internal energy, reflecting tighter binding between its atoms. Phases with a higher density (expressed as a lower molar volume V) are more stable at higher pressure, while minerals with a less ordered structure (expressed as a higher entropy S) are favored at high temperature. Thus andalusite is stable only at low pressure, since it has the lowest density of any aluminium silicate polymorph, while sillimanite is the stable form at higher temperatures, since it has the least ordered structure.[83]

The Gibbs free energy of a particular mineral at a specified temperature and pressure can be expressed by various analytic formulas. These are calibrated against experimentally measured properties and phase boundaries of mineral assemblages. The equilibrium mineral assemblage for a given bulk composition of rock at a specified temperature and pressure can then be calculated on a computer.[84][85]

However, it is often very useful to represent equilibrium mineral assemblages using various kinds of diagrams.[86] These include petrogenetic grids[87][88] and compatibility diagrams (compositional phase diagrams.)[89][90]

Petrogenetic grids

Main article: Petrogenetic grid

A petrogenetic grid is a geologic phase diagram that plots experimentally derived metamorphic reactions at their pressure and temperature conditions for a given rock composition. This allows metamorphic petrologists to determine the pressure and temperature conditions under which rocks metamorphose.[87][88] The Al2SiO5 nesosilicate phase diagram shown is a very simple petrogenetic grid for rocks that only have a composition consisting of aluminum (Al), silicon (Si), and oxygen (O). As the rock undergoes different temperatures and pressure, it could be any of the three given polymorphic minerals.[83] For a rock that contains multiple phases, the boundaries between many phase transformations may be plotted, though the petrogenetic grid quickly becomes complicated. For example, a petrogenetic grid might show both the aluminium silicate phase transitions and the transition from aluminum silicate plus potassium feldspar to muscovite plus quartz.[91]

Compatibility diagrams

Main article: Compatibility diagram

Whereas a petrogenetic grid shows phases for a single composition over a range of temperature and pressure, a compatibility diagram shows how the mineral assemblage varies with composition at a fixed temperature and pressure. Compatibility diagrams provide an excellent way to analyze how variations in the rock's composition affect the mineral paragenesis that develops in a rock at particular pressure and temperature conditions.[89][90] Because of the difficulty of depicting more than three components (as a ternary diagram), usually only the three most important components are plotted, though occasionally a compatibility diagram for four components is plotted as a projected tetrahedron.[92]

See also

Footnotes

  1. ^ a b Marshak 2009, p. 177.
  2. ^ Vernon 2008, p. 1.
  3. ^ a b Yardley 1989, pp. 1–5.
  4. ^ a b Yardley 1989, p. 5.
  5. ^ Yardley 1989, pp. 29–30.
  6. ^ Philpotts & Ague 2009, pp. 149, 420–425.
  7. ^ Bucher 2002, p. 4.
  8. ^ Nelson 2022.
  9. ^ Holland & Powell 2001.
  10. ^ Philpotts & Ague 2009, p. 252.
  11. ^ Philpotts & Ague 2009, p. 44.
  12. ^ a b Yardley 1989, pp. 49–51.
  13. ^ Yardley 1989, pp. 127, 154.
  14. ^ Jackson 1997, "metaquartzite".
  15. ^ Yardley 1989, pp. 154–158.
  16. ^ Gillen 1982, p. 31.
  17. ^ Howard 2005.
  18. ^ a b Yardley 1989, pp. 148–158.
  19. ^ Yardley 1989, p. 158.
  20. ^ Yardley 1989, pp. 32–33, 110, 130–131.
  21. ^ Yardley 1989, pp. 183–183.
  22. ^ a b Vernon 1976, p. 149.
  23. ^ Yardley 1989, pp. 110, 130–131.
  24. ^ Stern 2002, pp. 6–10.
  25. ^ Schmincke 2003, pp. 18, 113–126.
  26. ^ Stern 2002, pp. 27–28.
  27. ^ Yardley 1989, pp. 75, 102.
  28. ^ Yardley 1989, p. 127.
  29. ^ Boggs 2006, pp. 147–154.
  30. ^ a b Jackson 1997, "regional metamorphism".
  31. ^ Jackson 1997, "dynamothermal metamorphism".
  32. ^ Jackson 1997, "burial metamorphism".
  33. ^ a b c d e f g Yardley 1989, p. 12.
  34. ^ Kearey, Klepeis & Vine 2009, pp. 275–279.
  35. ^ Levin 2010, pp. 76–77, 82–83.
  36. ^ Yardley 1989, p. 22, 168-170.
  37. ^ Wicander & Munroe 2005, pp. 174–77.
  38. ^ Yuan et al. 2009, pp. 31–48.
  39. ^ Miyashiro 1973, pp. 368–369.
  40. ^ Philpotts & Ague 2009, p. 417.
  41. ^ Robinson et al. 2004, pp. 513–528.
  42. ^ Denison et al. 1987.
  43. ^ Smith, Perdrix & Parks 1982.
  44. ^ Marshak 2009, p. 187.
  45. ^ Jackson 1997, "aureole".
  46. ^ Yardley 1989, pp. 12, 26.
  47. ^ Blatt & Tracy 1996, pp. 367, 512.
  48. ^ Philpotts & Ague 2009, pp. 422, 428.
  49. ^ Yardley 1989, pp. 10–11.
  50. ^ Barker, Bone & Lewan 1998.
  51. ^ Yardley 1989, p. 43.
  52. ^ Philpotts & Ague 2009, p. 427.
  53. ^ Philpotts & Ague 2009, p. 422.
  54. ^ Yardley 1989, p. 126.
  55. ^ Rakovan 2007.
  56. ^ Buseck 1967.
  57. ^ Cooper et al. 1988.
  58. ^ Philpotts & Ague 2009, pp. 396–397.
  59. ^ Grapes 2011.
  60. ^ Sokol et al. 2005.
  61. ^ Marshak 2009, p. 190.
  62. ^ Philpotts & Ague 2009, pp. 70, 243, 346.
  63. ^ Yardley 1989, p. 13.
  64. ^ Mason 1990, pp. 94–106.
  65. ^ Jackson 1997, "cataclasis".
  66. ^ Brodie & Rutter 1985.
  67. ^ Fossen 2016, p. 185.
  68. ^ Fossen 2016, pp. 184–186.
  69. ^ Fossen 2016, p. 341.
  70. ^ Philpotts & Ague 2009, p. 441.
  71. ^ Philpotts & Ague 2009, p. 443.
  72. ^ Fossen 2016, p. 184.
  73. ^ Yardley 1989, p. 26.
  74. ^ Yardley 1989, pp. 21–27.
  75. ^ a b Robertson 1999.
  76. ^ a b Schmid et al. 2007.
  77. ^ a b Marshak 2009, p. 183.
  78. ^ Ghent 2020.
  79. ^ a b Blatt & Tracy 1996, p. 399.
  80. ^ Mitra 2004.
  81. ^ Philpotts & Ague 2009, p. 159.
  82. ^ Philpotts & Ague 2009, pp. 159–160.
  83. ^ a b Whitney 2002.
  84. ^ Holland & Powell 1998.
  85. ^ Philpotts & Ague 2009, pp. 161–162.
  86. ^ Philpotts & Ague 2009, pp. 447–470.
  87. ^ a b Yardley 1989, pp. 32–33, 52–55.
  88. ^ a b Philpotts & Ague 2009, pp. 424–425.
  89. ^ a b Yardley 1989, pp. 32–33.
  90. ^ a b Philpotts & Ague 2009, p. 447.
  91. ^ Philpotts & Ague 2009, p. 453.
  92. ^ Philpotts & Ague 2009, p. 454-455.

References

  • Barker, Charles E.; Bone, Yvonne; Lewan, Michael D. (September 1998). "Fluid inclusion and vitrinite-reflectance geothermometry compared to heat-flow models of maximum paleotemperature next to dikes, western onshore Gippsland Basin, Australia". International Journal of Coal Geology. 37 (1–2): 73–111. doi:10.1016/S0166-5162(98)00018-4.
  • Blatt, Harvey; Tracy, Robert J. (1996). Petrology : igneous, sedimentary, and metamorphic (2nd ed.). New York: W.H. Freeman. ISBN 0716724383.
  • Boggs, Sam (2006). Principles of sedimentology and stratigraphy (4th ed.). Upper Saddle River, N.J.: Pearson Prentice Hall. ISBN 0131547283.
  • Brodie, K. H.; Rutter, E. H. (1985). "On the Relationship between Deformation and Metamorphism, with Special Reference to the Behavior of Basic Rocks". Metamorphic Reactions. 4: 138–179. doi:10.1007/978-1-4612-5066-1_6.
  • Bucher, Kurt (2002). Petrogenesis of metamorphic rocks (7th completely rev. and updated ed.). Berlin: Springer. ISBN 9783540431305. Retrieved 2 February 2022.
  • Buseck, Peter R. (1 May 1967). "Contact metasomatism and ore deposition, Tem Piute, Nevada". Economic Geology. 62 (3): 331–353. doi:10.2113/gsecongeo.62.3.331.
  • Cooper, D. C.; Lee, M. K.; Fortey, N. J.; Cooper, A. H.; Rundle, C. C.; Webb, B. C.; Allen, P. M. (July 1988). "The Crummock Water aureole: a zone of metasomatism and source of ore metals in the English Lake District". Journal of the Geological Society. 145 (4): 523–540. doi:10.1144/gsjgs.145.4.0523.
  • Denison, R.E.; Bickford, M.E.; Lidiak, E.G.; Kisvarsanyi, E.B. (1987). "Geology and Geochronology of Precambrian Rocks in the Central Interior Region of the United States". Tulsa Geological Society Special Publication. 3 (`): 12–14. Retrieved 5 February 2022.
  • Eskola P., 1920, The Mineral Facies of Rocks, Norsk. Geol. Tidsskr., 6, 143–194
  • Fossen, Haakon (2016). Structural geology (Second ed.). Cambridge, United Kingdom: Cambridge University Press. p. 61. ISBN 9781107057647.
  • Ghent, Edward (1 July 2020). "Metamorphic facies: A review and some suggestions for changes". The Canadian Mineralogist. 58 (4): 437–444. doi:10.3749/canmin.1900078.
  • Gillen, Con (1982). Metamorphic geology : an introduction to tectonic and metamorphic processes. London: G. Allen & Unwin. ISBN 978-0045510580.
  • Grapes, R. H. (2011). Pyrometamorphism (2nd ed.). Berlin: Springer. ISBN 9783642155888.
  • Holland, T. J. B.; Powell, R. (1998). "An internally consistent thermodynamic data set for phases of petrological interest". Journal of Metamorphic Geology. 16 (3): 309–343. doi:10.1111/j.1525-1314.1998.00140.x.
  • Holland, Tim; Powell, Roger (2001). "Calculation of phase relations involving haplogranitic melts using an internally consistent thermodynamic dataset". Journal of Petrology. 42 (4): 673–683. Bibcode:2001JPet...42..673H. doi:10.1093/petrology/42.4.673.
  • Howard, Jeffrey L. (November 2005). "The Quartzite Problem Revisited". The Journal of Geology. 113 (6): 707–713. Bibcode:2005JG....113..707H. doi:10.1086/449328. S2CID 128463511.
  • Jackson, Julia A., ed. (1997). Glossary of geology (Fourth ed.). Alexandria, Virginia: American Geological Institute. ISBN 0922152349.
  • Kearey, P.; Klepeis, K.A.; Vine, F.J. (2009). Global tectonics (3rd ed.). Oxford: Wiley-Blackwell. pp. 184–188. ISBN 9781405107778.
  • Levin, Harold L. (2010). The earth through time (9th ed.). Hoboken, N.J.: J. Wiley. ISBN 978-0470387740.
  • Marshak, Stephen (2009). Essentials of Geology (3rd ed.). W. W. Norton & Company. ISBN 978-0393196566.
  • Mason, Roger (1990). "Dynamic metamorphism". Petrology of the metamorphic rocks. doi:10.1007/978-94-010-9603-4_4.
  • Mitra, Sachinath (2004). High-pressure geochemistry and mineral physics : basics for planetology and geo-material science. Amsterdam: Elsevier. p. 425. ISBN 9780080458229.
  • Miyashiro, Akiho (1973). Metamorphism and Metamorphic Belts. Dordrecht: Springer Netherlands. ISBN 9789401168366.</ref>
  • Nelson, Stephen A. "Types of Metamorphism". EENS 2120: Petrology. Tulane University. Retrieved 3 February 2022.
  • Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. ISBN 9780521880060.
  • Rakovan, John (2007). "Greisen" (PDF). Rocks and Minerals. 82: 157–159. Retrieved 6 February 2022.
  • Robertson, S. (1999). "BGS Rock Classification Scheme, Volume 2: Classification of metamorphic rocks" (PDF). British Geological Survey Research Report. RR 99-02. Retrieved 27 February 2021.
  • Robinson, D.; Bevins, R. E.; Aguirre, L.; Vergara, M. (1 January 2004). "A reappraisal of episodic burial metamorphism in the Andes of central Chile". Contributions to Mineralogy and Petrology. 146 (4): 513–528. Bibcode:2004CoMP..146..513R. doi:10.1007/s00410-003-0516-4. S2CID 140567746.
  • Schmid, R.; Fettes, D.; Harte, B.; Davis, E.; Desmons, J. (2007). "How to name a metamorphic rock.". Metamorphic Rocks: A Classification and Glossary of Terms: Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Metamorphic Rocks (PDF). Cambridge: Cambridge University Press. pp. 3–15. Retrieved 28 February 2021.
  • Schmincke, Hans-Ulrich (2003). Volcanism. Berlin: Springer. pp. 18, 113–126. ISBN 9783540436508.
  • Smith, R. E.; Perdrix, J. L.; Parks, T. C. (1 February 1982). "Burial Metamorphism in the Hamersley Basin, Western Australia". Journal of Petrology. 23 (1): 75–102. doi:10.1093/petrology/23.1.75.
  • Sokol, E.V.; Maksimova, N.V.; Nigmatulina, E.N.; Sharygin, V.V.; Kalugin, V.M. (2005). Combustion metamorphism (in Russian). Novosibirsk: Publishing House of the Siberian Branch of the Russian Academy of Sciences.
  • Stern, Robert J. (2002), "Subduction zones", Reviews of Geophysics, 40 (4): 6–10, Bibcode:2002RvGeo..40.1012S, doi:10.1029/2001RG000108
  • Vernon, R. H. (1976). Metamorphic processes : reactions and microstructure development. London: Murby. ISBN 978-0045520107.
  • Vernon, Ronald Holden (2008). Principles of Metamorphic Petrology. Cambridge University Press. ISBN 978-0521871785.
  • Whitney, D.L. (2002). "Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al2SiO5 polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey". American Mineralogist. 87 (4): 405–416. Bibcode:2002AmMin..87..405W. doi:10.2138/am-2002-0404. S2CID 131616262.
  • Wicander, R.; Munroe, J. (2005). Essentials of Geology. Cengage Learning. ISBN 978-0495013655.
  • Yardley, B. W. D. (1989). An introduction to metamorphic petrology. Harlow, Essex, England: Longman Scientific & Technical. ISBN 0582300967.
  • Yuan, S.; Pan, G.; Wang, L.; Jiang, X.; Yin, F.; Zhang, W.; Zhuo, J. (2009). "Accretionary Orogenesis in the Active Continental Margins". Earth Science Frontiers. 16 (3): 31–48. Bibcode:2009ESF....16...31Y. doi:10.1016/S1872-5791(08)60095-0.

Further reading

  • Winter J.D., 2001, An Introduction to Igneous and Metamorphic Petrology, Prentice-Hall ISBN 0-13-240342-0.

External links

  • Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks, 1. How to Name a Metamorphic Rock
  • Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks, 2. Types, Grade, and Facies of Metamorphism
  • Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks, 3. Structural terms including fault rock terms
  • Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks, 4. High P/T Metamorphic Rocks
  • James Madison University: Metamorphism
  • Barrovian Metamorphism: Brock Univ.
  • (MetPetDB) – Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute

January 20, 2023
metamorphism, other, uses, disambiguation, transformation, existing, rock, protolith, rock, with, different, mineral, composition, texture, takes, place, temperatures, excess, often, also, elevated, pressure, presence, chemically, active, fluids, rock, remains. For other uses see Metamorphism disambiguation Metamorphism is the transformation of existing rock the protolith to rock with a different mineral composition or texture Metamorphism takes place at temperatures in excess of 150 to 200 C 300 to 400 F and often also at elevated pressure or in the presence of chemically active fluids but the rock remains mostly solid during the transformation 1 Metamorphism is distinct from weathering or diagenesis which are changes that take place at or just beneath Earth s surface 2 Schematic representation of a metamorphic reaction Abbreviations of minerals act actinolite chl chlorite ep epidote gt garnet hbl hornblende plag plagioclase Two minerals represented in the figure do not participate in the reaction they can be quartz and K feldspar This reaction takes place in nature when a mafic rock goes from amphibolite facies to greenschist facies A cross polarized thin section image of a garnet mica schist from Salangen Norway showing the strong strain fabric of schists The black isotropic crystal is garnet the pink orange yellow colored strands are muscovite mica and the brown crystals are biotite mica The grey and white crystals are quartz and limited feldspar Various forms of metamorphism exist including regional contact hydrothermal shock and dynamic metamorphism These differ in the characteristic temperatures pressures and rate at which they take place and in the extent to which reactive fluids are involved Metamorphism occurring at increasing pressure and temperature conditions is known as prograde metamorphism while decreasing temperature and pressure characterize retrograde metamorphism Metamorphic petrology is the study of metamorphism Metamorphic petrologists rely heavily on statistical mechanics and experimental petrology to understand metamorphic processes Contents 1 Metamorphic processes 1 1 Recrystallization 1 2 Phase change 1 3 Neocrystallization 1 4 Plastic deformation 2 Types 2 1 Regional 2 1 1 Dynamothermal 2 1 2 Burial 2 2 Contact thermal 2 3 Hydrothermal 2 4 Shock 2 5 Dynamic 3 Classification of metamorphic rocks 3 1 Metamorphic grades 3 2 Metamorphic facies 3 3 Prograde and retrograde 4 Equilibrium mineral assemblages 4 1 Petrogenetic grids 4 2 Compatibility diagrams 5 See also 6 Footnotes 7 References 8 Further reading 9 External linksMetamorphic processes Edit Left Randomly orientated grains in a rock before metamorphism Right Grains align orthogonal to the applied stress if a rock is subjected to stress during metamorphism Metamorphism is the set of processes by which existing rock is transformed physically or chemically at elevated temperature without actually melting to any great degree The importance of heating in the formation of metamorphic rock was first recognized by the pioneering Scottish naturalist James Hutton who is often described as the father of modern geology Hutton wrote in 1795 that some rock beds of the Scottish Highlands had originally been sedimentary rock but had been transformed by great heat 3 Hutton also speculated that pressure was important in metamorphism This hypothesis was tested by his friend James Hall who sealed chalk into a makeshift pressure vessel constructed from a cannon barrel and heated it in an iron foundry furnace Hall found that this produced a material strongly resembling marble rather than the usual quicklime produced by heating of chalk in the open air French geologists subsequently added metasomatism the circulation of fluids through buried rock to the list of processes that help bring about metamorphism However metamorphism can take place without metasomatism isochemical metamorphism or at depths of just a few hundred meters where pressures are relatively low for example in contact metamorphism 3 Rock can be transformed without melting because heat causes atomic bonds to break freeing the atoms to move and form new bonds with other atoms Pore fluid present between mineral grains is an important medium through which atoms are exchanged 4 This permits recrystallization of existing minerals or crystallization of new minerals with different crystalline structures or chemical compositions neocrystallization 1 The transformation converts the minerals in the protolith into forms that are more stable closer to chemical equilibrium under the conditions of pressure and temperature at which metamorphism takes place 5 6 Metamorphism is generally regarded to begin at temperatures of 100 to 200 C 212 to 392 F This excludes diagenetic changes due to compaction and lithification which result in the formation of sedimentary rocks 7 The upper boundary of metamorphic conditions lies at the solidus of the rock which is the temperature at which the rock begins to melt At this point the process becomes an igneous process 8 The solidus temperature depends on the composition of the rock the pressure and whether the rock is saturated with water Typical solidus temperatures range from 650 C 1 202 F for wet granite at a few hundred megapascals Mpa of pressure 9 to about 1 080 C 1 980 F for wet basalt at atmospheric pressure 10 Migmatites are rocks formed at this upper limit which contains pods and veins of material that has started to melt but has not fully segregated from the refractory residue 11 The metamorphic process can occur at almost any pressure from near surface pressure for contact metamorphism to pressures in excess of 16 kbar 1500 Mpa 12 Recrystallization Edit Basalt hand sample showing fine texture Amphibolite formed by metamorphism of basalt showing coarse texture The change in the grain size and orientation in the rock during the process of metamorphism is called recrystallization For instance the small calcite crystals in the sedimentary rocks limestone and chalk change into larger crystals in the metamorphic rock marble 13 In metamorphosed sandstone recrystallization of the original quartz sand grains results in very compact quartzite also known as metaquartzite in which the often larger quartz crystals are interlocked 14 Both high temperatures and pressures contribute to recrystallization High temperatures allow the atoms and ions in solid crystals to migrate thus reorganizing the crystals while high pressures cause solution of the crystals within the rock at their points of contact pressure solution and redeposition in pore space 15 During recrystallization the identity of the mineral does not change only its texture Recrystallization generally begins when temperatures reach above half the melting point of the mineral on the Kelvin scale 16 Pressure solution begins during diagenesis the process of lithification of sediments into sedimentary rock but is completed during early stages of metamorphism For a sandstone protolith the dividing line between diagenesis and metamorphism can be placed at the point where strained quartz grains begin to be replaced by new unstrained small quartz grains producing a mortar texture that can be identified in thin sections under a polarizing microscope With increasing grade of metamorphism further recrystallization produces foam texture characterized by polygonal grains meeting at triple junctions and then porphyroblastic texture characterized by coarse irregular grains including some larger grains porphyroblasts 17 A mylonite through a petrographic microscope Metamorphic rocks are typically more coarsely crystalline than the protolith from which they formed Atoms in the interior of a crystal are surrounded by a stable arrangement of neighboring atoms This is partially missing at the surface of the crystal producing a surface energy that makes the surface thermodynamically unstable Recrystallization to coarser crystals reduces the surface area and so minimizes the surface energy 18 Although grain coarsening is a common result of metamorphism rock that is intensely deformed may eliminate strain energy by recrystallizing as a fine grained rock called mylonite Certain kinds of rock such as those rich in quartz carbonate minerals or olivine are particularly prone to form mylonites while feldspar and garnet are resistant to mylonitization 19 Phase change Edit Kyanite Andalusite Sillimanite Phase diagram of Al2SiO5 nesosilicates Phase change metamorphism is the creating of a new mineral with the same chemical formula as a mineral of the protolith This involves a rearrangement of the atoms in the crystals An example is provided by the aluminium silicate minerals kyanite andalusite and sillimanite All three have the identical composition Al2SiO5 Kyanite is stable at surface conditions However at atmospheric pressure kyanite transforms to andalusite at a temperature of about 190 C 374 F Andalusite in turn transforms to sillimanite when the temperature reaches about 800 C 1 470 F At pressures above about 4 kbar 400 Mpa kyanite transforms directly to sillimanite as the temperature increases 20 A similar phase change is sometimes seen between calcite and aragonite with calcite transforming to aragonite at elevated pressure and relatively low temperature 21 Neocrystallization Edit Neocrystallization involves the creation of new mineral crystals different from the protolith Chemical reactions digest the minerals of the protolith which yields new minerals This is a very slow process as it can also involve the diffusion of atoms through solid crystals 22 An example of a neocrystallization reaction is the reaction of fayalite with plagioclase at elevated pressure and temperature to form garnet The reaction is 23 fayalite 3 Fe2 SiO4 plagioclase CaAl2 Si2 O8 garnet 2 CaFe2 Al2 Si3 O12 Reaction 1 Many complex high temperature reactions may take place between minerals without them melting and each mineral assemblage produced provides us with a clue as to the temperatures and pressures at the time of metamorphism These reactions are possible because of rapid diffusion of atoms at elevated temperature Pore fluid between mineral grains can be an important medium through which atoms are exchanged 4 A particularly important group of neocrystallization reactions are those that release volatiles such as water and carbon dioxide During metamorphism of basalt to eclogite in subduction zones hydrous minerals break down producing copious quantities of water 24 The water rises into the overlying mantle where it lowers the melting temperature of the mantle rock generating magma via flux melting 25 The mantle derived magmas can ultimately reach the Earth s surface resulting in volcanic eruptions The resulting arc volcanoes tend to produce dangerous eruptions because their high water content makes them extremely explosive 26 Examples of dehydration reactions that release water include 27 hornblende 7Ca2Mg3Al4Si6O22 OH 2 quartz 1010SiO2 cummingtonite 3Mg7Si8O22 OH 2 anorthite 14CaAl2Si2O8 water 4H2O Reaction 2 muscovite 2KAl2 AlSi3O10 OH 2 quartz 2SiO2 sillimanite 2Al2SiO5 potassium feldspar 2KAlSi3O8 water 2H2O Reaction 3 An example of a decarbonation reaction is 28 calcite CaCO3 quartz SiO2 wollastonite CaSiO3 carbon dioxide CO2 Reaction 4 Plastic deformation Edit In plastic deformation pressure is applied to the protolith which causes it to shear or bend but not break In order for this to happen temperatures must be high enough that brittle fractures do not occur but not so high that diffusion of crystals takes place 22 As with pressure solution the early stages of plastic deformation begin during diagenesis 29 Types EditRegional Edit Regional metamorphism is a general term for metamorphism that affects entire regions of the Earth s crust 30 It most often refers to dynamothermal metamorphism which takes place in orogenic belts regions where mountain building is taking place 31 but also includes burial metamorphism which results simply from rock being buried to great depths below the Earth s surface in a subsiding basin 32 33 Dynamothermal Edit A metamorphic rock deformed during the Variscan orogeny at Vall de Cardos Lerida Spain To many geologists regional metamorphism is practically synonymous with dynamothermal metamorphism 30 This form of metamorphism takes place at convergent plate boundaries where two continental plates or a continental plate and an island arc collide The collision zone becomes a belt of mountain formation called an orogeny The orogenic belt is characterized by thickening of the Earth s crust during which the deeply buried crustal rock is subjected to high temperatures and pressures and is intensely deformed 33 34 Subsequent erosion of the mountains exposes the roots of the orogenic belt as extensive outcrops of metamorphic rock 35 characteristic of mountain chains 33 Metamorphic rock formed in these settings tends to shown well developed foliation 33 Foliation develops when a rock is being shortened along one axis during metamorphism This causes crystals of platy minerals such as mica and chlorite to become rotated such that their short axes are parallel to the direction of shortening This results in a banded or foliated rock with the bands showing the colors of the minerals that formed them Foliated rock often develops planes of cleavage Slate is an example of a foliated metamorphic rock originating from shale and it typically shows well developed cleavage that allows slate to be split into thin plates 36 The type of foliation that develops depends on the metamorphic grade For instance starting with a mudstone the following sequence develops with increasing temperature The mudstone is first converted to slate which is a very fine grained foliated metamorphic rock characteristic of very low grade metamorphism Slate in turn is converted to phyllite which is fine grained and found in areas of low grade metamorphism Schist is medium to coarse grained and found in areas of medium grade metamorphism High grade metamorphism transforms the rock to gneiss which is coarse to very coarse grained 37 Rocks that were subjected to uniform pressure from all sides or those that lack minerals with distinctive growth habits will not be foliated Marble lacks platy minerals and is generally not foliated which allows its use as a material for sculpture and architecture Collisional orogenies are preceded by subduction of oceanic crust 38 The conditions within the subducting slab as it plunges toward the mantle in a subduction zone produce their own distinctive regional metamorphic effects characterized by paired metamorphic belts 39 The pioneering work of George Barrow on regional metamorphism in the Scottish Highlands showed that some regional metamorphism produces well defined mappable zones of increasing metamorphic grade This Barrovian metamorphism is the most recognized metamorphic series in the world However Barrovian metamorphism is specific to pelitic rock formed from mudstone or siltstone and it is not unique even in pelitic rock A different sequence in the northeast of Scotland defines Buchan metamorphism which took place at lower pressure than the Barrovian 40 Burial Edit Sioux Quartzite a product of burial metamorphism Burial metamorphism takes place simply through rock being buried to great depths below the Earth s surface in a subsiding basin 33 Here the rock subjected to high temperatures and the great pressure caused by the immense weight of the rock layers above Burial metamorphism tends to produced low grade metamorphic rock This shows none of the effects of deformation and folding so characteristic of dynamothermal metamorphism 41 Examples of metamorphic rocks formed by burial metamorphism include some of the rocks of the Midcontinent Rift System of North America such as the Sioux Quartzite 42 and in the Hamersley Basin of Australia 43 Contact thermal Edit A metamorphic aureole in the Henry Mountains Utah The greyish rock on top is the igneous intrusion consisting of porphyritic granodiorite from the Henry Mountains laccolith and the pinkish rock on the bottom is the sedimentary country rock a siltstone In between the metamorphosed siltstone is visible as both the dark layer 5 cm thick and the pale layer below it Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole 44 the contact aureole or simply the aureole 45 Contact metamorphic rocks are usually known as hornfels Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine grained 46 47 and extremely tough 48 Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact 49 The size of the aureole depends on the heat of the intrusion its size and the temperature difference with the wall rocks Dikes generally have small aureoles with minimal metamorphism extending not more than one or two dike thicknesses into the surrounding rock 50 whereas the aureoles around batholiths can be up to several kilometers wide 51 52 The metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole This is usually related to the metamorphic temperatures of pelitic or aluminosilicate rocks and the minerals they form The metamorphic grades of aureoles at shallow depth are albite epidote hornfels hornblende hornfels pyroxene hornfels and sillimanite hornfels in increasing order of temperature of formation However the albite epidote hornfels is often not formed even though it is the lowest temperature grade 53 Magmatic fluids coming from the intrusive rock may also take part in the metamorphic reactions An extensive addition of magmatic fluids can significantly modify the chemistry of the affected rocks In this case the metamorphism grades into metasomatism If the intruded rock is rich in carbonate the result is a skarn 54 Fluorine rich magmatic waters which leave a cooling granite may often form greisens within and adjacent to the contact of the granite 55 Metasomatic altered aureoles can localize the deposition of metallic ore minerals and thus are of economic interest 56 57 Fenitization or Na metasomatism is a distinctive form of contact metamorphism accompanied by metasomatism It takes place around intrusions of a rare type of magma called a carbonatite that is highly enriched in carbonates and low in silica Cooling bodies of carbonatite magma give off highly alkaline fluids rich in sodium as they solidify and the hot reactive fluid replaces much of the mineral content in the aureole with sodium rich minerals 58 A special type of contact metamorphism associated with fossil fuel fires is known as pyrometamorphism 59 60 Hydrothermal Edit Hydrothermal metamorphism is the result of the interaction of a rock with a high temperature fluid of variable composition The difference in composition between an existing rock and the invading fluid triggers a set of metamorphic and metasomatic reactions The hydrothermal fluid may be magmatic originate in an intruding magma circulating groundwater or ocean water 33 Convective circulation of hydrothermal fluids in the ocean floor basalts produces extensive hydrothermal metamorphism adjacent to spreading centers and other submarine volcanic areas The fluids eventually escape through vents on the ocean floor known as black smokers 61 The patterns of this hydrothermal alteration are used as a guide in the search for deposits of valuable metal ores 62 Shock Edit Main article Shock metamorphism Shock metamorphism occurs when an extraterrestrial object a meteorite for instance collides with the Earth s surface Impact metamorphism is therefore characterized by ultrahigh pressure conditions and low temperature The resulting minerals such as SiO2 polymorphs coesite and stishovite and textures are characteristic of these conditions 63 Dynamic Edit Dynamic metamorphism is associated with zones of high strain such as fault zones 33 In these environments mechanical deformation is more important than chemical reactions in transforming the rock The minerals present in the rock often do not reflect conditions of chemical equilibrium and the textures produced by dynamic metamorphism are more significant than the mineral makeup 64 There are three deformation mechanisms by which rock is mechanically deformed These are cataclasis the deformation of rock via the fracture and rotation of mineral grains 65 plastic deformation of individual mineral crystals and movement of individual atoms by diffusive processes 66 The textures of dynamic metamorphic zones are dependent on the depth at which they were formed as the temperature and confining pressure determine the deformation mechanisms which predominate 67 At the shallowest depths a fault zone will be filled with various kinds of unconsolidated cataclastic rock such as fault gouge or fault breccia At greater depths these are replaced by consolidated cataclastic rock such as crush breccia in which the larger rock fragments are cemented together by calcite or quartz At depths greater than about 5 kilometers 3 1 mi cataclasites appear these are quite hard rocks consist of crushed rock fragments in a flinty matrix which forms only at elevated temperature At still greater depths where temperatures exceed 300 C 572 F plastic deformation takes over and the fault zone is composed of mylonite Mylonite is distinguished by its strong foliation which is absent in most cataclastic rock 68 It is distinguished from the surrounding rock by its finer grain size 69 There is considerable evidence that cataclasites form as much through plastic deformation and recrystallization as brittle fracture of grains and that the rock may never fully lose cohesion during the process Different minerals become ductile at different temperatures with quartz being among the first to become ductile and sheared rock composed of different minerals may simultaneously show both plastic deformation and brittle fracture 70 The strain rate also affects the way in which rocks deform Ductile deformation is more likely at low strain rates less than 10 14 sec 1 in the middle and lower crust but high strain rates can cause brittle deformation At the highest strain rates the rock may be so strongly heated that it briefly melts forming a glassy rock called pseudotachylite 71 72 Pseudotachylites seem to be restricted to dry rock such as granulite 73 Classification of metamorphic rocks EditMain article Metamorphic rock Classification Metamorphic rocks are classified by their protolith if this can be determined from the properties of the rock itself For example if examination of a metamorphic rock shows that its protolith was basalt it will be described as a metabasalt When the protolith cannot be determined the rock is classified by its mineral composition or its degree of foliation 74 75 76 Metamorphic grades Edit Metamorphic grade is an informal indication of the amount or degree of metamorphism 77 In the Barrovian sequence described by George Barrow in zones of progressive metamorphism in Scotland metamorphic grades are also classified by mineral assemblage based on the appearance of key minerals in rocks of pelitic shaly aluminous origin Low grade Intermediate High grade Greenschist Amphibolite Granulite Slate Phyllite Schist Gneiss Migmatite Chlorite zoneBiotite zoneGarnet zoneStaurolite zoneKyanite zoneSillimanite zone dd dd dd dd dd dd dd dd dd dd dd dd dd dd dd A more complete indication of this intensity or degree is provided by the concept of metamorphic facies 77 Metamorphic facies Edit Main article Metamorphic facies Metamorphic facies are recognizable terranes or zones with an assemblage of key minerals that were in equilibrium under specific range of temperature and pressure during a metamorphic event The facies are named after the metamorphic rock formed under those facies conditions from basalt 78 The particular mineral assemblage is somewhat dependent on the composition of that protolith so that for example the amphibolite facies of a marble will not be identical with the amphibolite facies of a pellite However the facies are defined such that metamorphic rock with as broad a range of compositions as is practical can be assigned to a particular facies The present definition of metamorphic facies is largely based on the work of the Finnish geologist Pentti Eskola in 1921 with refinements based on subsequent experimental work Eskola drew upon the zonal schemes based on index minerals that were pioneered by the British geologist George Barrow 12 The metamorphic facies is not usually considered when classifying metamorphic rock based on protolith mineral mode or texture However a few metamorphic facies produce rock of such distinctive character that the facies name is used for the rock when more precise classification is not possible The chief examples are amphibolite and eclogite The British Geological Survey strongly discourages use of granulite as a classification for rock metamorphosed to the granulite facies Instead such rock will often be classified as a granofels 75 However this is not universally accepted 76 Temperatures and pressures of metamorphic facies Temperature Pressure FaciesLow Low ZeoliteLower Moderate Lower Moderate Prehnite PumpellyiteModerate to High Low HornfelsLow to Moderate Moderate to High BlueschistModerate High Moderate Greenschist Amphibolite GranuliteModerate to High High EclogiteSee diagram for more detail Prograde and retrograde Edit Metamorphism is further divided into prograde and retrograde metamorphism Prograde metamorphism involves the change of mineral assemblages paragenesis with increasing temperature and usually pressure conditions These are solid state dehydration reactions and involve the loss of volatiles such as water or carbon dioxide Prograde metamorphism results in rock characteristic of the maximum pressure and temperature experienced Metamorphic rocks usually do not undergo further change when they are brought back to the surface 79 Retrograde metamorphism involves the reconstitution of a rock via revolatisation under decreasing temperatures and usually pressures allowing the mineral assemblages formed in prograde metamorphism to revert to those more stable at less extreme conditions This is a relatively uncommon process because volatiles produced during prograde metamorphism usually migrate out of the rock and are not available to recombine with the rock during cooling Localized retrograde metamorphism can take place when fractures in the rock provide a pathway for groundwater to enter the cooling rock 79 Equilibrium mineral assemblages Edit Petrogenetic grid showing aluminium silicate muscovite quartz K feldspar phase boundaries ACF compatibility diagrams aluminium calcium iron showing phase equilibria in metamorphic mafic rocks at different P T circumstances metamorphic facies Dots represent mineral phases thin grey lines are equilibria between two phases Mineral abbreviations act actinolite cc calcite chl chlorite di diopside ep epidote glau glaucophane gt garnet hbl hornblende ky kyanite law lawsonite plag plagioclase om omphacite opx orthopyroxene zo zoisite Metamorphic processes act to bring the protolith closer to thermodynamic equilibrium which is its state of maximum stability For example shear stress nonhydrodynamic stress is incompatible with thermodynamic equilibrium so sheared rock will tend to deform in ways that relieve the shear stress 80 The most stable assemblage of minerals for a rock of a given composition is that which minimizes the Gibbs free energy 81 G p T U p V T S displaystyle G p T U pV TS where U is the internal energy SI unit joule p is pressure SI unit pascal V is volume SI unit m3 T is the temperature SI unit kelvin S is the entropy SI unit joule per kelvin In other words a metamorphic reaction will take place only if it lowers the total Gibbs free energy of the protolith Recrystallization to coarser crystals lowers the Gibbs free energy by reducing surface energy 18 while phase changes and neocrystallization reduce the bulk Gibbs free energy A reaction will begin at the temperature and pressure where the Gibbs free energy of the reagents becomes greater than that of the products 82 A mineral phase will generally be more stable if it has a lower internal energy reflecting tighter binding between its atoms Phases with a higher density expressed as a lower molar volume V are more stable at higher pressure while minerals with a less ordered structure expressed as a higher entropy S are favored at high temperature Thus andalusite is stable only at low pressure since it has the lowest density of any aluminium silicate polymorph while sillimanite is the stable form at higher temperatures since it has the least ordered structure 83 The Gibbs free energy of a particular mineral at a specified temperature and pressure can be expressed by various analytic formulas These are calibrated against experimentally measured properties and phase boundaries of mineral assemblages The equilibrium mineral assemblage for a given bulk composition of rock at a specified temperature and pressure can then be calculated on a computer 84 85 However it is often very useful to represent equilibrium mineral assemblages using various kinds of diagrams 86 These include petrogenetic grids 87 88 and compatibility diagrams compositional phase diagrams 89 90 Petrogenetic grids Edit Main article Petrogenetic grid A petrogenetic grid is a geologic phase diagram that plots experimentally derived metamorphic reactions at their pressure and temperature conditions for a given rock composition This allows metamorphic petrologists to determine the pressure and temperature conditions under which rocks metamorphose 87 88 The Al2SiO5 nesosilicate phase diagram shown is a very simple petrogenetic grid for rocks that only have a composition consisting of aluminum Al silicon Si and oxygen O As the rock undergoes different temperatures and pressure it could be any of the three given polymorphic minerals 83 For a rock that contains multiple phases the boundaries between many phase transformations may be plotted though the petrogenetic grid quickly becomes complicated For example a petrogenetic grid might show both the aluminium silicate phase transitions and the transition from aluminum silicate plus potassium feldspar to muscovite plus quartz 91 Compatibility diagrams Edit Main article Compatibility diagram Whereas a petrogenetic grid shows phases for a single composition over a range of temperature and pressure a compatibility diagram shows how the mineral assemblage varies with composition at a fixed temperature and pressure Compatibility diagrams provide an excellent way to analyze how variations in the rock s composition affect the mineral paragenesis that develops in a rock at particular pressure and temperature conditions 89 90 Because of the difficulty of depicting more than three components as a ternary diagram usually only the three most important components are plotted though occasionally a compatibility diagram for four components is plotted as a projected tetrahedron 92 See also EditGeothermobarometry History of rock pressure and temperature Metamorphosis of snow Ultra high temperature metamorphism Crustal metamorphism with temperatures exceeding 900 CFootnotes Edit a b Marshak 2009 p 177 Vernon 2008 p 1 a b Yardley 1989 pp 1 5 a b Yardley 1989 p 5 Yardley 1989 pp 29 30 Philpotts amp Ague 2009 pp 149 420 425 Bucher 2002 p 4 Nelson 2022 Holland amp Powell 2001 Philpotts amp Ague 2009 p 252 Philpotts amp Ague 2009 p 44 a b Yardley 1989 pp 49 51 Yardley 1989 pp 127 154 Jackson 1997 metaquartzite Yardley 1989 pp 154 158 Gillen 1982 p 31 Howard 2005 a b Yardley 1989 pp 148 158 Yardley 1989 p 158 Yardley 1989 pp 32 33 110 130 131 Yardley 1989 pp 183 183 a b Vernon 1976 p 149 Yardley 1989 pp 110 130 131 Stern 2002 pp 6 10 Schmincke 2003 pp 18 113 126 Stern 2002 pp 27 28 Yardley 1989 pp 75 102 Yardley 1989 p 127 Boggs 2006 pp 147 154 a b Jackson 1997 regional metamorphism Jackson 1997 dynamothermal metamorphism Jackson 1997 burial metamorphism a b c d e f g Yardley 1989 p 12 Kearey Klepeis amp Vine 2009 pp 275 279 Levin 2010 pp 76 77 82 83 Yardley 1989 p 22 168 170 Wicander amp Munroe 2005 pp 174 77 Yuan et al 2009 pp 31 48 Miyashiro 1973 pp 368 369 Philpotts amp Ague 2009 p 417 Robinson et al 2004 pp 513 528 Denison et al 1987 Smith Perdrix amp Parks 1982 Marshak 2009 p 187 Jackson 1997 aureole Yardley 1989 pp 12 26 Blatt amp Tracy 1996 pp 367 512 Philpotts amp Ague 2009 pp 422 428 Yardley 1989 pp 10 11 Barker Bone amp Lewan 1998 Yardley 1989 p 43 Philpotts amp Ague 2009 p 427 Philpotts amp Ague 2009 p 422 Yardley 1989 p 126 Rakovan 2007 Buseck 1967 Cooper et al 1988 Philpotts amp Ague 2009 pp 396 397 Grapes 2011 Sokol et al 2005 Marshak 2009 p 190 Philpotts amp Ague 2009 pp 70 243 346 Yardley 1989 p 13 Mason 1990 pp 94 106 Jackson 1997 cataclasis Brodie amp Rutter 1985 Fossen 2016 p 185 Fossen 2016 pp 184 186 Fossen 2016 p 341 Philpotts amp Ague 2009 p 441 Philpotts amp Ague 2009 p 443 Fossen 2016 p 184 Yardley 1989 p 26 Yardley 1989 pp 21 27 a b Robertson 1999 a b Schmid et al 2007 a b Marshak 2009 p 183 Ghent 2020 a b Blatt amp Tracy 1996 p 399 Mitra 2004 Philpotts amp Ague 2009 p 159 Philpotts amp Ague 2009 pp 159 160 a b Whitney 2002 Holland amp Powell 1998 Philpotts amp Ague 2009 pp 161 162 Philpotts amp Ague 2009 pp 447 470 a b Yardley 1989 pp 32 33 52 55 a b Philpotts amp Ague 2009 pp 424 425 a b Yardley 1989 pp 32 33 a b Philpotts amp Ague 2009 p 447 Philpotts amp Ague 2009 p 453 Philpotts amp Ague 2009 p 454 455 References EditBarker Charles E Bone Yvonne Lewan Michael D September 1998 Fluid inclusion and vitrinite reflectance geothermometry compared to heat flow models of maximum paleotemperature next to dikes western onshore Gippsland Basin Australia International Journal of Coal Geology 37 1 2 73 111 doi 10 1016 S0166 5162 98 00018 4 Blatt Harvey Tracy Robert J 1996 Petrology igneous sedimentary and metamorphic 2nd ed New York W H Freeman ISBN 0716724383 Boggs Sam 2006 Principles of sedimentology and stratigraphy 4th ed Upper Saddle River N J Pearson Prentice Hall ISBN 0131547283 Brodie K H Rutter E H 1985 On the Relationship between Deformation and Metamorphism with Special Reference to the Behavior of Basic Rocks Metamorphic Reactions 4 138 179 doi 10 1007 978 1 4612 5066 1 6 Bucher Kurt 2002 Petrogenesis of metamorphic rocks 7th completely rev and updated ed Berlin Springer ISBN 9783540431305 Retrieved 2 February 2022 Buseck Peter R 1 May 1967 Contact metasomatism and ore deposition Tem Piute Nevada Economic Geology 62 3 331 353 doi 10 2113 gsecongeo 62 3 331 Cooper D C Lee M K Fortey N J Cooper A H Rundle C C Webb B C Allen P M July 1988 The Crummock Water aureole a zone of metasomatism and source of ore metals in the English Lake District Journal of the Geological Society 145 4 523 540 doi 10 1144 gsjgs 145 4 0523 Denison R E Bickford M E Lidiak E G Kisvarsanyi E B 1987 Geology and Geochronology of Precambrian Rocks in the Central Interior Region of the United States Tulsa Geological Society Special Publication 3 12 14 Retrieved 5 February 2022 Eskola P 1920 The Mineral Facies of Rocks Norsk Geol Tidsskr 6 143 194 Fossen Haakon 2016 Structural geology Second ed Cambridge United Kingdom Cambridge University Press p 61 ISBN 9781107057647 Ghent Edward 1 July 2020 Metamorphic facies A review and some suggestions for changes The Canadian Mineralogist 58 4 437 444 doi 10 3749 canmin 1900078 Gillen Con 1982 Metamorphic geology an introduction to tectonic and metamorphic processes London G Allen amp Unwin ISBN 978 0045510580 Grapes R H 2011 Pyrometamorphism 2nd ed Berlin Springer ISBN 9783642155888 Holland T J B Powell R 1998 An internally consistent thermodynamic data set for phases of petrological interest Journal of Metamorphic Geology 16 3 309 343 doi 10 1111 j 1525 1314 1998 00140 x Holland Tim Powell Roger 2001 Calculation of phase relations involving haplogranitic melts using an internally consistent thermodynamic dataset Journal of Petrology 42 4 673 683 Bibcode 2001JPet 42 673H doi 10 1093 petrology 42 4 673 Howard Jeffrey L November 2005 The Quartzite Problem Revisited The Journal of Geology 113 6 707 713 Bibcode 2005JG 113 707H doi 10 1086 449328 S2CID 128463511 Jackson Julia A ed 1997 Glossary of geology Fourth ed Alexandria Virginia American Geological Institute ISBN 0922152349 Kearey P Klepeis K A Vine F J 2009 Global tectonics 3rd ed Oxford Wiley Blackwell pp 184 188 ISBN 9781405107778 Levin Harold L 2010 The earth through time 9th ed Hoboken N J J Wiley ISBN 978 0470387740 Marshak Stephen 2009 Essentials of Geology 3rd ed W W Norton amp Company ISBN 978 0393196566 Mason Roger 1990 Dynamic metamorphism Petrology of the metamorphic rocks doi 10 1007 978 94 010 9603 4 4 Mitra Sachinath 2004 High pressure geochemistry and mineral physics basics for planetology and geo material science Amsterdam Elsevier p 425 ISBN 9780080458229 Miyashiro Akiho 1973 Metamorphism and Metamorphic Belts Dordrecht Springer Netherlands ISBN 9789401168366 lt ref gt Nelson Stephen A Types of Metamorphism EENS 2120 Petrology Tulane University Retrieved 3 February 2022 Philpotts Anthony R Ague Jay J 2009 Principles of igneous and metamorphic petrology 2nd ed Cambridge UK Cambridge University Press ISBN 9780521880060 Rakovan John 2007 Greisen PDF Rocks and Minerals 82 157 159 Retrieved 6 February 2022 Robertson S 1999 BGS Rock Classification Scheme Volume 2 Classification of metamorphic rocks PDF British Geological Survey Research Report RR 99 02 Retrieved 27 February 2021 Robinson D Bevins R E Aguirre L Vergara M 1 January 2004 A reappraisal of episodic burial metamorphism in the Andes of central Chile Contributions to Mineralogy and Petrology 146 4 513 528 Bibcode 2004CoMP 146 513R doi 10 1007 s00410 003 0516 4 S2CID 140567746 Schmid R Fettes D Harte B Davis E Desmons J 2007 How to name a metamorphic rock Metamorphic Rocks A Classification and Glossary of Terms Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Metamorphic Rocks PDF Cambridge Cambridge University Press pp 3 15 Retrieved 28 February 2021 Schmincke Hans Ulrich 2003 Volcanism Berlin Springer pp 18 113 126 ISBN 9783540436508 Smith R E Perdrix J L Parks T C 1 February 1982 Burial Metamorphism in the Hamersley Basin Western Australia Journal of Petrology 23 1 75 102 doi 10 1093 petrology 23 1 75 Sokol E V Maksimova N V Nigmatulina E N Sharygin V V Kalugin V M 2005 Combustion metamorphism in Russian Novosibirsk Publishing House of the Siberian Branch of the Russian Academy of Sciences Stern Robert J 2002 Subduction zones Reviews of Geophysics 40 4 6 10 Bibcode 2002RvGeo 40 1012S doi 10 1029 2001RG000108 Vernon R H 1976 Metamorphic processes reactions and microstructure development London Murby ISBN 978 0045520107 Vernon Ronald Holden 2008 Principles of Metamorphic Petrology Cambridge University Press ISBN 978 0521871785 Whitney D L 2002 Coexisting andalusite kyanite and sillimanite Sequential formation of three Al2SiO5 polymorphs during progressive metamorphism near the triple point Sivrihisar Turkey American Mineralogist 87 4 405 416 Bibcode 2002AmMin 87 405W doi 10 2138 am 2002 0404 S2CID 131616262 Wicander R Munroe J 2005 Essentials of Geology Cengage Learning ISBN 978 0495013655 Yardley B W D 1989 An introduction to metamorphic petrology Harlow Essex England Longman Scientific amp Technical ISBN 0582300967 Yuan S Pan G Wang L Jiang X Yin F Zhang W Zhuo J 2009 Accretionary Orogenesis in the Active Continental Margins Earth Science Frontiers 16 3 31 48 Bibcode 2009ESF 16 31Y doi 10 1016 S1872 5791 08 60095 0 Further reading EditWinter J D 2001 An Introduction to Igneous and Metamorphic Petrology Prentice Hall ISBN 0 13 240342 0 External links EditRecommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks 1 How to Name a Metamorphic Rock Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks 2 Types Grade and Facies of Metamorphism Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks 3 Structural terms including fault rock terms Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks 4 High P T Metamorphic Rocks James Madison University Metamorphism Barrovian Metamorphism Brock Univ Metamorphism of Carbonate Rocks University of Wisconsin Green Bay Metamorphic Petrology Database MetPetDB Department of Earth and Environmental Sciences Rensselaer Polytechnic Institute Retrieved from https en wikipedia org w index php title Metamorphism amp oldid 1118361081, wikipedia, wiki, book, books, library,

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