Metamorphism

Metamorphism

1. Instituted of Geology
6th Semester (Morning)
Submitted by: Raja Saad Qamar
Roll No: 37
Submitted To: Mam Shazia
Subject: sedimentation and sedimentary basin

2. 22

3. METAMORPHISMMETAMORPHISM

Metamorphism is consisting of two words Metamorphism is consisting of two words

Meta means “change” Meta means “change”

Morph means “shape”Morph means “shape”

So metamorphism is basically a change in So metamorphism is basically a change in
shape of pre exsisting rocksshape of pre exsisting rocks

Metamorphism is a sub surface processMetamorphism is a sub surface process

The bulk composition of rock remain same The bulk composition of rock remain same
in this processin this process
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4. MetamorphismMetamorphism

Metamorphism can occur along a range of heat Metamorphism can occur along a range of heat
and pressure intensities from and pressure intensities from low-low- to to high-grade high-grade
metamorphismmetamorphism. .

Low-grade metamorphismLow-grade metamorphism involves lower involves lower
temperature and compressional forces that temperature and compressional forces that
result in less overall change to the parent rock. result in less overall change to the parent rock.
In many cases, after low-grade metamorphic In many cases, after low-grade metamorphic
changes the parent rock , structure may still be changes the parent rock , structure may still be
easily distinguishable . such parental rock easily distinguishable . such parental rock
structure are called structure are called relict structurerelict structure

High-grade metamorphismHigh-grade metamorphism results in a total results in a total
transformation of the parent rock into a new transformation of the parent rock into a new
rock whereby its original parent-rock source is rock whereby its original parent-rock source is
difficult to identify. difficult to identify.
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5. What are Rocks?What are Rocks?

Most rocks are an aggregate of minerals ( few rocks are Most rocks are an aggregate of minerals ( few rocks are
composed of non-mineral matter)composed of non-mineral matter)

There are three major rock types: There are three major rock types:

1. Igneous1. Igneous

2. Metamorphic2. Metamorphic

3. Sedimentary3. Sedimentary
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6. The Rock CycleThe Rock Cycle
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7. The Role of Parent Rocks in The Role of Parent Rocks in
MetamorphismMetamorphism

Parent rocks provide the minerals and ion sources that are Parent rocks provide the minerals and ion sources that are
transformed into new minerals and rocks.transformed into new minerals and rocks.

In most cases the new metamorphic rock has the same chemical In most cases the new metamorphic rock has the same chemical
composition as the parent rock that they formed from. composition as the parent rock that they formed from.
SandstoneSandstone QuartziteQuartzite
SedimentarySedimentary MetamorphicMetamorphic
GraniteGranite GneissGneiss
IgneousIgneous MetamorphicMetamorphic
LimestoneLimestone MarbleMarble
SedimentarySedimentary MetamorphicMetamorphic
Examples of parent rocks and their metamorphic products:Examples of parent rocks and their metamorphic products:
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8. What is a metamorphic rock?What is a metamorphic rock?
The term "metamorphic" means "to change form." The term "metamorphic" means "to change form."
Any rock (igneous, sedimentary, or metamorphic) can become a Any rock (igneous, sedimentary, or metamorphic) can become a
metamorphicmetamorphic rock. If rocks are effected by high temperatures rock. If rocks are effected by high temperatures
and pressures and chemical active fluid, they form new minerals and pressures and chemical active fluid, they form new minerals
and textures all without melting. If melting occurs, magma is and textures all without melting. If melting occurs, magma is
formed, starting the rock cycle all over again. formed, starting the rock cycle all over again.

9. Types of pressure affected the Types of pressure affected the
process of metamorphismprocess of metamorphism

Directed pressureDirected pressure
the pressure which effects the pressure which effects
the rock in parallel direction due to which the rock in parallel direction due to which
foliation occurs in rocks foliation occurs in rocks
Uniform pressureUniform pressure
the pressure which effects the pressure which effects
the rocks in all direction and make the the rocks in all direction and make the
rock evengrained and equidimentionalrock evengrained and equidimentional
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10. Types of Metamorphic rocks in
the basis of composition
• Contact
- caused by igneous activity
• Dynamic

- associated with faults & earthquake zones
• Regional
- caused by tremendous pressures
associated with tectonic plate activity
• Contact
- caused by igneous activity
• Dynamic
- associated with faults & earthquake zones
• Regional
- caused by tremendous pressures
associated with tectonic plate activity

11. Contact MetamorphismContact Metamorphism
• Igneous Intrusions
- size and type of magma important
> mafic magma hotter than felsic
- heat decreases away from magma
> forms a zone of altered country rocks called
• Igneous Intrusions
- size and type of magma important
> mafic magma hotter than felsic
- heat decreases away from magma
> forms a zone of altered country rocks called Aureoles
Sometimes creates a metamorphic rock called a
hornfels -in essence a “cooked” rock

13. Dynamic MetamorphismDynamic Metamorphism
•
• associated with Fault Zones
- Places where the Earth's crust ruptured
- Rock pulverized
> heat and pressure come from movement along the
Fault
• resultant rock is known as a Mylonite
• Cataclastic Metamorphism
• associated with Fault Zones
- Places where the Earth's crust ruptured
- Rock pulverized
> heat and pressure come from movement along the
Fault
• resultant rock is known as a Mylonite

14. Regional MetamorphismRegional Metamorphism
• Most common form of metamorphism
• caused by large scale forces
- lithospheric plate collision
• covers very large areas
- metamorphic belts or zones
- Zones are characterized byIndex Minerals
> form under specific temperatures and pressures
> metamorphic facies
• commonly associated with
-
• Most common form of metamorphism
• caused by large scale forces
- lithospheric plate collision
• covers very large areas
- metamorphic belts or zones
- Zones are characterized byIndex Minerals
> form under specific temperatures and pressures
> metamorphic facies
• commonly associated with
- Shields and Mountains: areas of crystalline rocks

15. Metamorphic Rock TypesMetamorphic Rock Types
There are two types of metamorphic rocks.There are two types of metamorphic rocks.
Each is classified according to its texture.Each is classified according to its texture.

FoliatedFoliated

Non foliatedNon foliated

16. FOLIATED METAMORPHIC FOLIATED METAMORPHIC
ROCKSROCKS
FOLIATEDFOLIATED metamorphic rocks are those in which the minerals metamorphic rocks are those in which the minerals
have been flattened and pushed down into parallel layers. The have been flattened and pushed down into parallel layers. The
bands in foliated metamorphic rock look like pages in a book.bands in foliated metamorphic rock look like pages in a book.
Examples of foliated rocks are slate, shale, and gneiss.Examples of foliated rocks are slate, shale, and gneiss.

17. Foliated Metamorphic Rocks
slateslate
schistschist gneissgneiss
phyllitephyllite
MM Rocks that could form as a shale (sedimentary) parent rock is
exposed to increasing directed pressure and temperature
MM Rocks that could form as a shale (sedimentary) parent rock is
exposed to increasing directed pressure and temperature

18. Foliated Metamorphic RocksFoliated Metamorphic Rocks

SlateSlate

Phyllite Phyllite

SchistSchist

GneissGneiss
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South Carolina’s Piedmont is composed South Carolina’s Piedmont is composed
primarily of foliated metamorphic rocks. In primarily of foliated metamorphic rocks. In
many locations different metamorphic rock many locations different metamorphic rock
types occur in close proximity. Many of the types occur in close proximity. Many of the
metamorphic rocks in this region are folded and metamorphic rocks in this region are folded and
faulted, making for very exciting geology.faulted, making for very exciting geology.
Photo: SCGS
Photo: SCGS

19. Foliated Rocks: Foliated Rocks: SlateSlate

Slate is a fine-grained rock composed of mica flakes and quartz Slate is a fine-grained rock composed of mica flakes and quartz
grains that enable the rock to break into thin slabs of rock, along grains that enable the rock to break into thin slabs of rock, along
planes of slaty cleavage.planes of slaty cleavage.

Slate forms in low-grade metamorphic environments from a parent Slate forms in low-grade metamorphic environments from a parent
rock of either shale, mudstone, or siltstone.rock of either shale, mudstone, or siltstone.

Slate is commonly thought of as black, but it can also be red when it Slate is commonly thought of as black, but it can also be red when it
contains iron oxide minerals, or green when it contains chlorite. contains iron oxide minerals, or green when it contains chlorite.
Weathered slate may even appear light brown in the example below. Weathered slate may even appear light brown in the example below.
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Photo: SCGS
This example of slate is part of the Carolina This example of slate is part of the Carolina
Slate belt which traverses through the Slate belt which traverses through the
Piedmont of South Carolina. This image Piedmont of South Carolina. This image
also provides a good example of the slaty also provides a good example of the slaty
cleavage that has also been folded.cleavage that has also been folded.

20. Foliated Rocks: Foliated Rocks: PhyllitePhyllite

Phyllite is a low- to moderate-grade metamorphic rock that contains Phyllite is a low- to moderate-grade metamorphic rock that contains
aligned platy mica minerals and has slaty cleavage.aligned platy mica minerals and has slaty cleavage.

The individual crystals are fine grained and generally consist of The individual crystals are fine grained and generally consist of
muscovite, white mica, and chlorite (green rocks).muscovite, white mica, and chlorite (green rocks).

Phyllite has a satiny appearance and waxy texture.Phyllite has a satiny appearance and waxy texture.

Phyllite is a metamorphic form of shale, mudstone, and siltstone.Phyllite is a metamorphic form of shale, mudstone, and siltstone.
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These samples of phyllite all came These samples of phyllite all came
from the same quarry in South from the same quarry in South
Carolina. The slaty cleavage of the Carolina. The slaty cleavage of the
phyllite is what makes it a foliated phyllite is what makes it a foliated
rock. As phyllite weathers it parts along rock. As phyllite weathers it parts along
the cleavage planes.the cleavage planes.

21. Foliated Rocks:Foliated Rocks: SchistSchist

Schist exhibits schistosity, which is formed by the alignment of Schist exhibits schistosity, which is formed by the alignment of
platy medium- to coarse-grained minerals formed under moderate- platy medium- to coarse-grained minerals formed under moderate-
to high-grade metamorphic conditions.to high-grade metamorphic conditions.

Schists are primarily composed of silicate minerals such as mica Schists are primarily composed of silicate minerals such as mica
(muscovite and biotite), quartz, and feldspar .(muscovite and biotite), quartz, and feldspar .

Shale, siltstone, and some sandstones can provide the parent rock Shale, siltstone, and some sandstones can provide the parent rock
for schist.for schist.

Schist may contain accessory minerals such as garnet, tourmaline, Schist may contain accessory minerals such as garnet, tourmaline,
and pyrite.and pyrite.
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Photo: SCGS
This schist is from the Piedmont region in This schist is from the Piedmont region in
South Carolina. Notice how the different South Carolina. Notice how the different
layers are weathering at slightly different layers are weathering at slightly different
rates, the layers of darker, mica rich schist are rates, the layers of darker, mica rich schist are
weathering more quickly than the tan, weathering more quickly than the tan,
feldspar and quartz-rich layers. feldspar and quartz-rich layers.

22. Foliated Rocks: Foliated Rocks: GneissGneiss

Gneiss is a medium- to coarse-grained rock formed under high Gneiss is a medium- to coarse-grained rock formed under high
grade-metamorphic conditions.grade-metamorphic conditions.

Gneiss is primarily composed of quartz, potassium feldspar, and Gneiss is primarily composed of quartz, potassium feldspar, and
plagioclase feldspar with lesser amounts of biotite, muscovite, and plagioclase feldspar with lesser amounts of biotite, muscovite, and
amphibole.amphibole.

Granites and sometimes rhyolite provide the parent rock for gneiss.Granites and sometimes rhyolite provide the parent rock for gneiss.
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Photo: SCGS
Gneisses are generally light colored because Gneisses are generally light colored because
they contain a large amount of quartz and they contain a large amount of quartz and
feldspar. The alternating light and dark bands feldspar. The alternating light and dark bands
in this gneiss illustrate the segregation of in this gneiss illustrate the segregation of
different minerals during crystallization. This different minerals during crystallization. This
example also shows folds in the rock. This example also shows folds in the rock. This
gneiss most likely formed from a gneiss most likely formed from a
metamorphosed igneous intrusion. South metamorphosed igneous intrusion. South
Carolina’s Piedmont and Blue Ridge contain Carolina’s Piedmont and Blue Ridge contain
gneissic bedrock. gneissic bedrock.

23. Non-foliatedNon-foliated

NON-FOLIATEDNON-FOLIATED metamorphic rocks metamorphic rocks
do not display layers. Rather, they are do not display layers. Rather, they are
massive structures with no obvious massive structures with no obvious
banding. banding. The mineral grains grow The mineral grains grow
and rearrange, but they don’t form and rearrange, but they don’t form
layers. layers.

A good example of non-foliated rock is A good example of non-foliated rock is
quartzite, the smooth-textured, quartzite, the smooth-textured,
metamorphosed form of the mineral metamorphosed form of the mineral
quartz.quartz.

A coarse-textured non-foliated rock is A coarse-textured non-foliated rock is
marble. marble.

Anthracite, or hard coal, is a non-foliated Anthracite, or hard coal, is a non-foliated
rock that forms when intense pressure rock that forms when intense pressure
drives gases out of soft coal, causing it to drives gases out of soft coal, causing it to
harden.harden.

24. Nonfoliated Rocks: Nonfoliated Rocks: MarbleMarble

Marble is a nonfoliated, coarse-grained metamorphic rock formed Marble is a nonfoliated, coarse-grained metamorphic rock formed
from the parent rock limestone or dolomite.from the parent rock limestone or dolomite.

Because it is formed from limestone or dolomite it is predominantly Because it is formed from limestone or dolomite it is predominantly
composed of the mineral calcite, which metamorphoses into various composed of the mineral calcite, which metamorphoses into various
carbonate and other minerals. As calcite recrystallizes, all the grains carbonate and other minerals. As calcite recrystallizes, all the grains
are active at the same time and they grow to the same size and shape, are active at the same time and they grow to the same size and shape,
which leads to its nonfoliated texture.which leads to its nonfoliated texture.

Different colour schemes in marble are the result of impurities or the Different colour schemes in marble are the result of impurities or the
presence of weathered materials deposited in or near the limestone. presence of weathered materials deposited in or near the limestone.
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Marble is used as a building material and is Marble is used as a building material and is
popular for sculpture. The word ‘marble’ popular for sculpture. The word ‘marble’
derives from a Greek word that translates as derives from a Greek word that translates as
“shining stone” because it can be polished. “shining stone” because it can be polished.
Limestone that metamorphoses into marble Limestone that metamorphoses into marble
may contain a lot of fossils; however, the heat may contain a lot of fossils; however, the heat
and pressure of metamorphism destroys and pressure of metamorphism destroys
preexisting features primarily through preexisting features primarily through
recrystallization. recrystallization.
Copyright © Dr. Richard Busch

25. QuartziteQuartzite

Quartzite is a metamorphic rock formed under moderate to high-Quartzite is a metamorphic rock formed under moderate to high-
grade metamorphism that exhibits both foliated and nonfoliated grade metamorphism that exhibits both foliated and nonfoliated
structure.structure.

The parent rock to quartzite is sandstone.The parent rock to quartzite is sandstone.

Quartzite forms from the recrystallization of quartz grains in the Quartzite forms from the recrystallization of quartz grains in the
sandstone and often the resulting metamorphic rock will preserve sandstone and often the resulting metamorphic rock will preserve
vestiges of the original bedding patterns .vestiges of the original bedding patterns .

Quartz is predominantly white in color, but can also contain Quartz is predominantly white in color, but can also contain
pinkish or grayish shades depending on the presence of iron pinkish or grayish shades depending on the presence of iron
oxides. oxides.
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This example of quartzite show a couple of This example of quartzite show a couple of
interesting features. First, notice how the interesting features. First, notice how the
different bedding planes have been different bedding planes have been
preserved during the metamorphism. preserved during the metamorphism.
Secondly, there is a fault running though the Secondly, there is a fault running though the
quartzite that occurred after the formation of quartzite that occurred after the formation of
the rock. This particular example is of a the rock. This particular example is of a
foliated quartzite (due primarily to the foliated quartzite (due primarily to the
preservation of the bedding planes) however preservation of the bedding planes) however
some quartzite rocks are classified as some quartzite rocks are classified as
nonfoliated. nonfoliated.

26. Resources and ReferencesResources and References
Christopherson, R. W. ,2002, Geosystems (4Christopherson, R. W. ,2002, Geosystems (4
thth
ed.): Upper Saddle River, New Jersey, Prentice Hall. ed.): Upper Saddle River, New Jersey, Prentice Hall.
Christopherson, R. W., 2004, Elemental Geosystems (4Christopherson, R. W., 2004, Elemental Geosystems (4
thth
ed.): Upper Saddle River, New Jersey, Prentice Hall. ed.): Upper Saddle River, New Jersey, Prentice Hall.
Robertson, S., 1999, BGS Rock Classification Scheme, Volume 2, classification of metamorphic rocks: British Robertson, S., 1999, BGS Rock Classification Scheme, Volume 2, classification of metamorphic rocks: British
Geological Survey Research Report (2Geological Survey Research Report (2
ndnd
Edition) , RR 99-03. Edition) , RR 99-03.
Keller, E. A., 2000, Environmental Geology (8Keller, E. A., 2000, Environmental Geology (8
thth
ed.): Upper Saddle River, New Jersey, Prentice Hall. ed.): Upper Saddle River, New Jersey, Prentice Hall.
Lutgens, F. K., and Tarbuck. E. J., 2003, Essentials of Geology (8Lutgens, F. K., and Tarbuck. E. J., 2003, Essentials of Geology (8
thth
ed.): Upper Saddle River, New Jersey, Prentice Hall. ed.): Upper Saddle River, New Jersey, Prentice Hall.
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27. Summary Summary

Metamorphism is a subsurface process due to Metamorphism is a subsurface process due to
which change in shape, grain size, texture, which change in shape, grain size, texture,
structure occurs .it is time consuming process structure occurs .it is time consuming process
.changes occur by either directed or uniform .changes occur by either directed or uniform
pressure pressure

Due to uniform pressure rocks become even Due to uniform pressure rocks become even
grained and equidimentional grained and equidimentional

Due to directed pressure rocks become foliatedDue to directed pressure rocks become foliated
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28. TThhaannk k yyoou u
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