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Why are metamorphic rocks formed by contact metamorphism usually not as dense as those formed by regional metamorphism?
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∙ 14y ago
Contact metamorphism does not cause profound compaction, which is the reduction in size of the spaces between mineral particles due to increases in pressure. Regional metamorphism causes compaction and possibly recrystallization, increasing the density of the rock.
Wiki User
∙ 14y ago
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Why are metamorphic rocksformed by contact metamorphism usually not as dense as those formed by regional metamorphism?
Because contact metamorphism usually occurs because of an increase in temperature. In contrary, regional metamorphism is usually the result of compression. Compression makes a rock more dense.
Why are metamorphic rocks formed by contact metamorphism usually not as dense as those formed by reg?
Because in contact the rock actually comes in contact with magma, this joins with the rock, so when it cools and become igneous rock, it's denser. In regular, or regional, the rock is formed from intense heat and pressure, but does not actually come in contact with magma.
which rock is only formed by regional metamorphasim?
The heat generated by the magma chamber has changed these sedimentary rocks into the metamorphic rocks marble, quartzite, and hornfels. Regional Metamorphism occurs over a much larger area. This metamorphism produces rocks such as gneiss and schist.
What happens each time a metamorphic rock is exposed to extreme heat and pressure?
Metamorphic Rock Metamorphism means to change form; this is exactly what metamorphic rocks do. This paper will take a look at the Earth's rock cycle to examine exactly where the metamorphic rock fits into it. It will also look at how metamorphic rocks are formed and the relationship between metamorphic rocks and igneous rock and sedimentary rocks. This paper will examine the geological characteristics and materials of metamorphic rocks, and examine some examples of metamorphic rocks and will describe mineral composition of some examples and explain its economic uses. The Rock Cycle The rock cycle helps people to understand the starting point of the igneous, sedimentary, and metamorphic rocks. In addition to explaining how each of the rocks are connected through the process. The rock cycle explains to us how the Earth assists in changing one type of rock into another type of rock. The process begins when magma, found from beneath the Earth's surface or from a volcano, cools and crystallizes. This process forms rocks called igneous rocks. When an igneous rock is exposed to weathering and erosion and compacted by the weight of the groundwater, which is otherwise known as lithification, it creates a sedimentary rock. When sedimentary rocks are buried deep within the Earth and evolve into mountains or are exposed to extreme pressure and intense heat it will then turn into the last cycle of rock, the metamorphic rock. Metamorphic rocks can even evolve from other metamorphic rocks. How Metamorphic Rocks Are Formed Within the Rock Cycle Metamorphic rocks are created when they are exposed to extreme heat, pressure, and chemicals. Rocks are usually exposed to extreme heat, pressure, and chemicals at the same time. Metamorphism occurs in one of two situations, contact metamorphism or regional metamorphism. Contact metamorphism occurs when a rocks experience a rise in temperature when it is exposed to magma. Heat is the most important source of metamorphism because... [continues]
What type of rock would result from the metamorphism of granite?
Granite is Igneous rock. It crystallizes from hot melt (magma). Metamorphic rocks can be found associated with granite as result of their contact with country (surrounding) rocks. This will be a contact metamorphism. Metamorphism of granite it self results into granitic gneisses which are coarse foliated rocks.
Why are metamorphic rocksformed by contact metamorphism usually not as dense as those formed by regional metamorphism?
Because contact metamorphism usually occurs because of an increase in temperature. In contrary, regional metamorphism is usually the result of compression. Compression makes a rock more dense.
What are two ways that can poduce metamorphic rocks?
Two ways in which metamorphic rocks are 1) contact metamorphism (thermal) where magma comes in direct contact with surrounding igneous rock and changes it due to high temperatures and usually low pressure. 2) Regional metamorphism (dynamothermal) ,high pressures and low temperature eg mountain ranges. or 3) Cataclastic metamorphism, heat as a result of friction due to two plate meeting or passing each other.
What is the most common type of metamorphism?
The most common type of land metamorphism is Regional metamorphism. The most common rocks are slates, schists, and gneisses. This occurs within the folds of mountain belts and cratonic areas.
Where does contact (prograde) occur?
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. Contact metamorphic rocks are usually known ashornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained.
Why are metamorphic rocks formed by contact metamorphism usually not as dense as those formed by reg?
Because in contact the rock actually comes in contact with magma, this joins with the rock, so when it cools and become igneous rock, it's denser. In regular, or regional, the rock is formed from intense heat and pressure, but does not actually come in contact with magma.
which rock is only formed by regional metamorphasim?
The heat generated by the magma chamber has changed these sedimentary rocks into the metamorphic rocks marble, quartzite, and hornfels. Regional Metamorphism occurs over a much larger area. This metamorphism produces rocks such as gneiss and schist.
What is an example of a metamorphic rock?
One of the most popular metamorphic rocks is marble. Originally limestone, marble is generally created through regional metamorphism, which is when pressure and heat from where magma is pushing up through the Earth's crust effect rocks which are close by, but not actually touching the magma. Contact metamorphism changes the rocks that do actually touch the magma, this is how shale is usually metamorphosed into gneiss.
How does an igneous rock change to metamorphic?
Meta-igneous. Metamorphism of igneous rocks can form a wide range of metamorphic rocks, depending on the mineralogy of the igneous protolith and the P-T conditions of the metamorphism.
What rocks are Metamorphic rock?
== == Rocks that have undergone a change in mineral structure or composition, without melting, through heat and/or pressure are metamorphic rocks. Examples are slate, anthracite, and gneiss.How does contact (prograde) occur? the changes in mineral assemblage and mineral composition that occur during burial and heating are referred to as prograde metamorphism.Where does contact (prograde) occur? 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. Contact metamorphic rocks are usually known ashornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained.Why does contact (prograde) occur? 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.[5] Contact metamorphic rocks are usually known ashornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained.Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact. 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 whereas large ultramafic intrusions can have significantly thick and well-developed contact metamorphism.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 ofpelitic or alumonisilicate rocks and the minerals they form.The metamorphic grades of aureoles are andalusite hornfels, sillimanite hornfels, pyroxene hornfels.Magmatic fluids coming from the intrusive rock may also take part in the metamorphic reactions. 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. Fluorine-rich magmatic waters which leave a cooling granite may often form greisens within and adjacent to the contact of the granite. Metasomatic altered aureoles can localize the deposition of metallic oreminerals and thus are of economic interest.Prograde and retrograde metamorphism[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.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 must be present.Garnets with Mn-rich cores and Mn-poorer rims record growth zoning that represents the change from the lower-T conditions at which the garnet core grew to the higher-T conditions at which the garnet rim grew (i.e., prograde metamorphism involving increasing temperature and pressure). Mn is preferentially partitioned into garnet relative to most other common minerals, so Mn is sequestered in early-formed garnet, depleting the local environment of the growing garnet in Mn.(b) Minerals that show major element growth zoning probably did not experience very high metamorphic temperatures. At high temperature (> 700 C) and sufficient duration, zoning may be homogenized as intracrystalline diffusion becomes more effective at eliminating compositional variation. An unzoned mineral that is typically zoned at low-medium metamorphic grades has either experienced high temperature conditions or was never zoned (owing to a simple reaction history at limited P-T or to growth entirely at high-T).
What does metamorphic rocks mean?
== == Rocks that have undergone a change in mineral structure or composition, without melting, through heat and/or pressure are metamorphic rocks. Examples are slate, anthracite, and gneiss.How does contact (prograde) occur? the changes in mineral assemblage and mineral composition that occur during burial and heating are referred to as prograde metamorphism.Where does contact (prograde) occur? 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. Contact metamorphic rocks are usually known ashornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained.Why does contact (prograde) occur? 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.[5] Contact metamorphic rocks are usually known ashornfels. Rocks formed by contact metamorphism may not present signs of strong deformation and are often fine-grained.Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact. 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 whereas large ultramafic intrusions can have significantly thick and well-developed contact metamorphism.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 ofpelitic or alumonisilicate rocks and the minerals they form.The metamorphic grades of aureoles are andalusite hornfels, sillimanite hornfels, pyroxene hornfels.Magmatic fluids coming from the intrusive rock may also take part in the metamorphic reactions. 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. Fluorine-rich magmatic waters which leave a cooling granite may often form greisens within and adjacent to the contact of the granite. Metasomatic altered aureoles can localize the deposition of metallic oreminerals and thus are of economic interest.Prograde and retrograde metamorphism[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.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 must be present.Garnets with Mn-rich cores and Mn-poorer rims record growth zoning that represents the change from the lower-T conditions at which the garnet core grew to the higher-T conditions at which the garnet rim grew (i.e., prograde metamorphism involving increasing temperature and pressure). Mn is preferentially partitioned into garnet relative to most other common minerals, so Mn is sequestered in early-formed garnet, depleting the local environment of the growing garnet in Mn.(b) Minerals that show major element growth zoning probably did not experience very high metamorphic temperatures. At high temperature (> 700 C) and sufficient duration, zoning may be homogenized as intracrystalline diffusion becomes more effective at eliminating compositional variation. An unzoned mineral that is typically zoned at low-medium metamorphic grades has either experienced high temperature conditions or was never zoned (owing to a simple reaction history at limited P-T or to growth entirely at high-T).
What happens each time a metamorphic rock is exposed to extreme heat and pressure?
Metamorphic Rock Metamorphism means to change form; this is exactly what metamorphic rocks do. This paper will take a look at the Earth's rock cycle to examine exactly where the metamorphic rock fits into it. It will also look at how metamorphic rocks are formed and the relationship between metamorphic rocks and igneous rock and sedimentary rocks. This paper will examine the geological characteristics and materials of metamorphic rocks, and examine some examples of metamorphic rocks and will describe mineral composition of some examples and explain its economic uses. The Rock Cycle The rock cycle helps people to understand the starting point of the igneous, sedimentary, and metamorphic rocks. In addition to explaining how each of the rocks are connected through the process. The rock cycle explains to us how the Earth assists in changing one type of rock into another type of rock. The process begins when magma, found from beneath the Earth's surface or from a volcano, cools and crystallizes. This process forms rocks called igneous rocks. When an igneous rock is exposed to weathering and erosion and compacted by the weight of the groundwater, which is otherwise known as lithification, it creates a sedimentary rock. When sedimentary rocks are buried deep within the Earth and evolve into mountains or are exposed to extreme pressure and intense heat it will then turn into the last cycle of rock, the metamorphic rock. Metamorphic rocks can even evolve from other metamorphic rocks. How Metamorphic Rocks Are Formed Within the Rock Cycle Metamorphic rocks are created when they are exposed to extreme heat, pressure, and chemicals. Rocks are usually exposed to extreme heat, pressure, and chemicals at the same time. Metamorphism occurs in one of two situations, contact metamorphism or regional metamorphism. Contact metamorphism occurs when a rocks experience a rise in temperature when it is exposed to magma. Heat is the most important source of metamorphism because... [continues]
What type of rock would result from the metamorphism of granite?
Granite is Igneous rock. It crystallizes from hot melt (magma). Metamorphic rocks can be found associated with granite as result of their contact with country (surrounding) rocks. This will be a contact metamorphism. Metamorphism of granite it self results into granitic gneisses which are coarse foliated rocks.
