what is metamorphism process

Metamorphism is a process of mineral assemblage and texture variation that results from the physical-chemical changes of solid rocks, caused by factors such as crust movement, magma activity, or thermal fluid change in the earth. The metamorphism comprises recrystallization, metamorphic

crystallization, deformation, fragmentation, and alternation.

Full Answer

Where do most metamorphic processes take place?

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. The solidus temperature depends on the composition of the rock, the pressure, and whether the rock is saturated with water.

What does metamorphism result from?

Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.

What are the three types of metamorphism?

What are the four types of metamorphism?

• Type # 1. Contact Metamorphism:
• Type # 2. Regional Metamorphism:
• Type # 3. Hydro-Metamorphism:
• Type # 4. Hydro-Thermo-Metamorphism:

What is the metamorphic process?

Process of Metamorphism: The process of metamorphism does not melt the rocks, but instead transforms them into denser, more compact rocks. New minerals are created either by rearrangement of mineral components or by reactions with fluids that enter the rocks. Pressure or temperature can even change previously metamorphosed rocks into new types.

What are the three processes of metamorphism?

The three types of metamorphism are Contact, Regional, and Dynamic metamorphism. Contact Metamorphism occurs when magma comes in contact with an already existing body of rock. When this happens the existing rocks temperature rises and also becomes infiltrated with fluid from the magma.

What is metamorphic process give example?

Metamorphosis is a biological process which involves sudden and abrupt changes in the body structure of the animal by cell growth and differentiation. It is generally observed in amphibians and insects. Examples: frogs and butterflies.

What are the two processes of metamorphism?

Equally as significant are changes in chemical environment that result in two metamorphic processes: (1) mechanical dislocation where a rock is deformed, especially as a consequence of differential stress; and (2) chemical recrystallization where a mineral assemblage becomes out of equilibrium due to temperature and ...

What is the best definition of metamorphism?

Definition of metamorphism : a change in the constitution of rock specifically : a pronounced change effected by pressure, heat, and water that results in a more compact and more highly crystalline condition.

What causes metamorphism?

Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.

What is metamorphosis and its types?

Complete and incomplete metamorphosis are two types of growth forms in insects. The complete metamorphosis occurs through four stages: egg, larva, pupa, and adult. The incomplete metamorphosis occurs through three stages: egg, nymph, and adult. The pupa stage is not developed during incomplete metamorphosis.

What is the importance of metamorphism?

valuable, because metamorphic minerals and rocks have economic value. For example, slate and marble are building materials, garnets are used as gemstones and abrasives, talc is used in cosmetics, paints, and lubricants, and asbestos is used for insulation and fireproofing.

What is the most common form of metamorphism?

Large amounts of granitic intrusions are also associated with regional metamorphic rocks. The most common regional metamorphic rocks are slates, schists and gneisses.

Where does metamorphism take place?

Contact metamorphism takes place around magma bodies in the upper part of the crust, which are also most common above convergent boundaries. Geologists classify metamorphic rocks based on some key minerals—such as chlorite, garnet, andalusite, and sillimanite—that form at specific temperatures and pressures.

What process creates metamorphic rock?

The conditions required to form a metamorphic rock are very specific. The existing rock must be exposed to high heat, high pressure, or to a hot, mineral-rich fluid. Usually, all three of these circumstances are met.

How metamorphic rocks are formed step by step?

0:000:43How do metamorphic rocks form - YouTubeYouTubeStart of suggested clipEnd of suggested clipAs a result of tectonic plate movement both sedimentary rocks and igneous rocks could be pushed deepMoreAs a result of tectonic plate movement both sedimentary rocks and igneous rocks could be pushed deep beneath the earth's surface tongues of magma pushing upwards heat the rock strongly.

Which is metamorphic process apex?

Answer and Explanation: Metamorphic process apex refers to the highest level of metamorphosis a rock will undergo to the point that it will no longer change into another kind of metamorphic rock. Metamorphic forces end where the combined heat and pressure melts the rock into what will cool and become an igneous rock.

What is a metamorphic sentence?

Metamorphic sentence example. metamorphic. The central plateau consists almost entirely of metamorphic rocks with extensive tracts of granite in Unyamwezi.

What is metamorphism in geology?

Metamorphism. Metamorphism is a process of mineral assemblage and texture variation that results from the physical-chemical changes of solid rocks, caused by factors such as crust movement, magma activity, or thermal fluid change in the earth. From: Unconventional Petroleum Geology, 2013. Download as PDF. About this page.

What is burial metamorphism?

Burial metamorphism (Coombs, 1961) is a type of very low-grade metamorphism, which results from partial to complete recrystallization of deeply buried sedimentary and volcanic rocks at depths and temperatures in excess of 10 km and 200–300 °C respectively and along low to medium- P / T ratios ( Spear, 1993; Smulikowski et al., 2007; Bucher and Grapes, 2011 ). Although of regional extent, the geological setting of burial metamorphism characteristically lacks orogenesis, synchronous magmatism and deviatoric stress. The resultant rocks largely preserve original rock fabrics and display incomplete mineral transformations. The metamorphic minerals are commonly restricted to veins, vesicles, interstices and alteration zones. At deeper levels of burial metamorphism, there is circulation of hot hydrous fluids at an elevated geothermal gradient and the metamorphism overlaps with hydrothermal metamorphism.

What is metamorphism in subduction zones?

Metamorphism in subduction zones transforms crustal rocks into given mineral assemblages under given pressure (P)-temperature (T) conditions. This gives rise to metamorphic rocks with different peak thermobaric ratios, which can be translated into metamorphic thermal gradients. As a consequence, regional metamorphism along convergent plate boundaries is classified into three types. The first is low T/P Alpine type at low thermal gradients, resulting in blueschist to eclogites facies series at high to ultrahigh pressure. The second is moderate T/P Barrovian type at moderate thermal gradients, leading to amphibolite to granulite facies series at medium to high pressures. The third is high T/P Buchan type at high thermal gradients, giving rise to amphibolite to granulite facies series at medium through high to ultrahigh temperatures. As such, three metamorphic facies series can be produced within different P/T fields, providing a genetic link to dynamic regimes at convergent plate boundaries. Whereas compressional heating is responsible for prograde Alpine and Barrovian type metamorphism at lower thermal gradients during subduction, extensional heating is responsible for Buchan type metamorphism at elevated thermal gradients during rifting. This yields contrasting thermal gradients for bimodal metamorphism in ongoing and fossil subduction zones. Consequently, their products show different relationships in space to different types of orogen. Whereas paired metamorphic belts are separated from each other along accretionary orogens, polymetamorphic products are superimposed on each other along collisional orogens. Therefore, the change of thermal gradients with time is a key to the understanding of regional metamorphism at convergent plate boundaries.

What are the factors that affect the magnetization of sedimentary rocks?

A wide variety of factors affect the magnetization of metamorphosed sedimentary rocks. The iron content of sediments, which is generally higher for pellites than for psammites, and the redox conditions during deposition and diagenesis will largely determine the capacity of sedimentary rocks to develop secondary magnetite during metamorphism ( McIntrye, 1980 ). Significant chemical input by exhalative metal-bearing solutions, including iron, also enhances likelihood for magnetite formation during subsequent metamorphism. Magnetite formation also depends on the oxidation state during metamorphism, which should be intermediate between that which favors ilmenite and that which favors hematite. Magnetite can be produced from high-grade metamorphism of hematite-bearing sediments ( Clark, 1997 ). Finally, metamorphism of organic-rich sediments usually produces graphitic rocks that lack magnetite but may include magnetic pyrrhotite. In the end, magnetic anomaly patterns observed over metasedimentary rocks reflect both sedimentary-facies variations as well as metamorphic conditions ( McIntrye, 1980 ).

What is the product of the existing rock?

The product of the existing rock (igneous and sedimentary rocks) suffering metamorphism is called metamorphic rock (Winkler, 1975) whose chemical composition is related not only to original rock, but also to metamorphism.

How does metamorphism affect sedimentary rocks?

The changes brought about include the formation of new minerals, increase in grain size, and modification of rock structure or texture, all of which depend on the original rock’s composition and the intensity of the metamorphism.

What are the main agents of metamorphism?

The principal agents of metamorphism are temperature, pressure, infiltrating fluids and deformation. Metamorphic processes occur well beneath the earth's surface, so they cannot be observed directly. It is generally accepted that some metamorphic rocks can be created by simple burial to sufficient depth, but that most metamorphic rocks now exposed at the surface were affected by some additional process such as mountain-building (orogeny), alteration by an adjacent igneous body, intense deformation, etc. In the field, differential uplift and erosion may produce a surface exposure that cuts across an initial gradient in temperature and pressure with depth that accompanied initial metamorphism. A series of metamorphic rocks may thus be revealed that were exposed to differing grades of metamorphism. One might then walk across rocks ranging from unmetamorphosed into progressively higher metamorphic grades. Characteristic metamorphic index minerals may be used to distinguish zones of progressively higher grade across such a transect. The pre-metamorphic parent rock is called the protolith. Metamorphic rocks are classified on the basis of mineralogy and texture. The protolith, temperature and pressure of metamorphic equilibration, and effects of deformation are the principal controls governing the resulting rock and its name. A proper study of metamorphic rocks allows interpretation of the physical conditions developed at a geographic area during one or more metamorphic events. Understanding the relations between the metamorphic rocks and the protoliths of each further allows a researcher to infer such things as sedimentary environments that existed prior to metamorphism. When combined with age dating and structural analysis the geologic history of various areas can be interpreted.

How does metamorphism occur?

Three types of metamorphism may occur depending on the relative effect of mechanical and chemical changes. Dynamic metamorphism, or cataclasis, results mainly from mechanical deformation with little long-term temperature change. Textures produced by such adjustments range from breccias composed of angular, shattered rock fragments to very fine-grained, granulated or powdered rocks with obvious foliationand lineation. Large, pre-existing mineral grains may be deformed as a result of stress. Contact metamorphismoccurs primarily as a consequence of increases in temperature when differential stress is minor. A common phenomenon is the effect produced adjacentto igneous intrusions where several metamorphic zones represented by changing mineral assemblages reflect the temperature gradient from the high-temperature intrusion to the low-temperature host rocks; these zones are concentric to the intrusion. Because the volume affected is small, the pressure is near constant. Resulting rocks have equidimensional grains because of a lack of stress and are usually fine-grained due to the short duration of metamorphism. Regional metamorphismresults from the general increase, usually correlated, of temperature and pressure over a large area. Grades or intensities of metamorphism are represented by different mineral assemblages that either give relative values of temperature or absolute values when calibratedagainst laboratory experiments. Regional metamorphism can be subdivided into different pressure-temperature conditions based on observed sequences of mineral assemblages. It may include an extreme condition, where partial meltingoccurs, called anatexis.

What is regional metamorphism?

Regional metamorphism can be subdivided into different pressure-temperature conditions based on observed sequences of mineral assemblages. It may include an extreme condition, where partial meltingoccurs, called anatexis. Other types of metamorphism can occur. They are retrograde metamorphism, the response of mineral assemblages to decreasing ...

What are the most important agents of metamorphism?

Changes produced by surface conditions such as compactionare usually excluded. The most important agents of metamorphism include temperature, pressure, and fluids.

What is the term for new minerals formed at the expense of earlier ones?

mineral: Occurrence and formation. >metamorphic, in which new minerals form at the expense of earlier ones owing to the effects of changing—usually increasing—temperature or pressure or both on some existing rock type, and (4) hydrothermal, in which minerals are chemically precipitated from hot solutions within Earth.

Why do rocks have equidimensional grains?

Resulting rocks have equidimensional grains because of a lack of stress and are usually fine-grained due to the short duration of metamorphism. Regional metamorphismresults from the general increase, usually correlated, of temperature and pressure over a large area.

How does contact metamorphism differ from dynamic metamorphism?

Contact metamorphism occurs as zones a few hundred metres wide around large igneous intrusions while dynamic metamorphism is restricted to fault and thrust zones only a few tens of metres thick. All three types of metamorphism can overlap.

What are the three main types of metamorphism?

The three main types of metamorphism are: Contact (also known as thermal) metamorphism: this is produced by high temperature, low pressure, low strain and variable fluid pressure.

What is metamorphic rock?

Metamorphic rocks are pre-existing rocks whose mineral composition and/or texture has been changed by processes within the Earth. Discover more. You have reached the end of the main content. Go back to start of main content.

How can minerals be identified?

Minerals can be identified by the shape of their crystals: called crystallography. External crystallography measures the outside properties of crystals such as length of crystal surfaces and the angles between these surfaces.

What are the factors that cause metamorphic changes?

The important factors that produce metamorphic changes are. pressure deep within the crust. temperature. strain (shape and volume changes as a result of stress during deformation) fluid activity (pressure due to fluids in pore spaces within the original rocks) Toggle Caption.

What is the rock cycle?

The rock cycle is a collection of processes which shape the surface of the Earth. Rocks are constantly recycled by burial, melting, uplift and erosion. During metamorphic processes, few components (e.g. fluorine, boron), other than water, enter or leave rocks. No overall chemical changes occur; instead, the original chemical constituents are just ...

What is the importance of gem deposits?

Since the 1950s, several discoveries have led to a new understanding of how the Earth works. Gem deposits are a very important group of mineral deposits, forming in a variety of geological environments and occurring in rocks of all ages from thousands of millions to recent times.

What is the process of metamorphism?

6.2: Metamorphic Processes. Metamorphism occurs when solid rock changes in composition and/or texture without the mineral crystals melting , which is how igneous rock is generated. Metamorphic source rocks, the rocks that experience the metamorphism, are called the parent rock or protolith, from proto – meaning first, and lithos- meaning rock.

How does metamorphism occur?

Metamorphism occurs when solid rock changes in composition and/or texture without the mineral crystals melting, which is how igneous rock is generated. Metamorphic source rocks, the rocks that experience the metamorphism, are called the parent rock or protolith, from proto – meaning first, and lithos- meaning rock. Most metamorphic processes take place deep underground, inside the earth’s crust. During metamorphism, protolith chemistry is mildly changed by increased temperature (heat), a type of pressure called confining pressure, and/or chemically reactive fluids. Rock texture is changed by heat, confining pressure, and a type of pressure called directed stress.

What are the minerals that are produced by fluids-activated metamorphism?

For example, the mining districts in the Cottonwood Canyons and Mineral Basin of northern Utah produce valuable ores such as argentite (silver sulfide), galena (lead sulfide), and chalcopyrite (copper-iron sulfide), as well as the native element gold [ 2 ] . These mineral deposits were created from the interaction between a granitic intrusion called the Little Cottonwood Stock and country-rock consisting of mostly limestone and dolostone. Hot, circulating fluids expelled by the crystallizing granite reacted with and dissolved the surrounding limestone and dolostone, precipitating out new minerals created by the chemical reaction. Hydrothermal alteration of mafic mantle rock, such as olivine and basalt, creates the metamorphic rock serpentinite, a member of the serpentine subgroup of minerals. This metamorphic process happens at mid-ocean spreading centers where newly formed oceanic crust interacts with seawater.

What are the three metamorphic agents?

These reactive fluids are made of mostly water (H 2 O) and carbon dioxide (CO 2 ), and smaller amounts of potassium (K), sodium (Na), iron (Fe), magnesium (Mg), calcium (Ca), and aluminum (Al). These fluids react with minerals in the protolith, changing its chemical equilibrium and mineral composition, in a process similar to the reactions driven by heat and pressure. In addition to using elements found in the protolith, the chemical reaction may incorporate substances contributed by the fluids to create new minerals. In general, this style of metamorphism, in which fluids play an important role, is called hydrothermal metamorphism or hydrothermal alteration. Water actively participates in chemical reactions and allows extra mobility of the components in hydrothermal alteration.

How does pressure affect metamorphic rocks?

The pressure that affects metamorphic rocks can be grouped into confining pressure and directed stress. Stress is a scientific term indicating a force. Strain is the result of this stress, including metamorphic changes within minerals.

What temperature does metamorphism occur?

Heat-driven metamorphism begins at temperatures as cold as 200˚C and can continue to occur at temperatures as high as 700°C-1,100°C [ 3; 4; 5 ].

How does hydrothermal alterations occur?

This happens when seawater circulates down through fractures in the fresh, still-hot basalt, reacting with and removing mineral ions from it. The dissolved minerals are usually ions that do not fit snugly in the silicate crystal structure, such as copper. The mineral-laden water emerges from the seafloor via hydrothermal vents called black smokers, named after the dark-colored precipitates produced when the hot vent water meets cold seawater. (see Chapter 4, Igneous Rock and Volcanic Processes) Ancient black smokers were an important source of copper ore for the inhabitants of Cyprus (Cypriots) as early as 4,000 BCE, and later by the Romans [ 8 ].

What does metamorphism mean in science?

In fact, if we look at the word metamorphism, we see that it comes from the word 'morph,' which means to be transformed or changed. So, metamorphic rocks are previously formed rocks that have been transformed by exposure to heat and/or pressure. paywall_metamorphism-of-rocks-definition-process-influencing-factors. 5:11.

What is the metamorphic process by which the chemical composition of a rock is changed by fluids and heat?

This is seen when shale that contains clay minerals change to produce the new mineral garnet. Metasomatism is the metamorphic process by which the chemical composition of a rock is changed by fluids and heat. This is seen in the creation of anthracite coal. Learning Outcomes.

What is the process of changing the shape of a rock?

There are different metamorphic processes that are responsible for the changes that we see in these rocks. Recrystallization is the most common and is defined as the metamorphic process by which crystals are packed together creating a new crystal structure. Recrystallization requires a lot of heat and pressure, and the process changes the mineral's size and shape, yet the basic composition remains unchanged.

How does metamorphism affect crystals?

The pressure involved in metamorphism may come from the rock being deeply buried and this creates such intense pressure that crystals within the rock can grow together or collapse and rearrange into new mineral crystals. We also see that metamorphic rocks may be influenced by a third factor: the chemically active fluids that circulate around the newly forming rock and introduce different ions, which cause new and different mineral crystals to grow.

What is metamorphic rock?

Metamorphic rocks are previously formed rocks that have been transformed by exposure to heat and/or pressure. Along with heat and pressure we see that chemically active fluids are also one of the influencing factors that can transform pre-existing rock into metamorphic rock.

Why are metamorphic rocks the unlucky rocks of the world?

Metamorphic rocks are the unlucky rocks of the world because they got to their current state after being tortured by intense heat and pressure. In fact, if we look at the word metamorphism, we see that it comes from the word 'morph,' which means to be transformed or changed.

What is the term for a rock that is changed by fluids and heat?

This is the metamorphic process by which the chemical composition of a rock is changed by fluids and heat. It may help you to recall this term if you remember that 'soma' can refer to a hallucinogenic or mind-altering beverage that was used as an offering to the Hindu gods.

How is metamorphic rock formed?

Metamorphic rock, estimated to be as old as 3.8 billion years, located near Isua at Qorqut Sound, Greenland. rock formed by the cooling of magma or lava. molten rock, or magma, that erupts from volcanoes or fissures in the Earth's surface. molten, or partially melted, rock beneath the Earth's surface.

Why do metamorphic rocks break down?

This happens due to geologic uplift and the erosion of the rock and soil above them. At the surface, metamorphic rocks will be exposed to weathering processes and may break down into sediment. These sediments could then be compressed to form sedimentary rocks, which would start the entire cycle anew.

How did igneous and sedimentary rocks form?

Igneous rocks formed when liquid magma or lava —magma that has emerged onto the surface of the Earth —cooled and hardened.

What are the conditions required to form a metamorphic rock?

The conditions required to form a metamorphic rock are very specific. The existing rock must be exposed to high heat, high pressure, or to a hot, mineral-rich fluid. Usually, all three of these circumstances are met.

What is the relationship between the three rock types?

Noun. movement and interaction of the Earth's plates. rock cycle. Noun. processes that explain the relationship between the three rock types: igneous, sedimentary, and metamorphic. Any rock type can become any other. sedimentary rock. Noun. rock formed from fragments of other rocks or the remains of plants or animals.

Why does limestone turn into marble?

Limestone, a sedimentary rock, will change into the metamorphic rock marble if the right conditions are met. Although metamorphic rocks typically form deep in the planet’s crust, they are often exposed on the surface of the Earth. This happens due to geologic uplift and the erosion of the rock and soil above them.

What is the name of the rock that forms when granite is subjected to intense heat and pressure?

When granite is subjected to intense heat and pressure, it changes into a metamorphic rock called gneiss. Slate is another common metamorphic rock that forms from shale. Limestone, a sedimentary rock, will change into the metamorphic rock marble if the right conditions are met.