Metamorfisme dan batuan metamorfik

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Metamorfisme dan batuan metamorfik
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HOW WHERE
CONTACT
METAMORFISME
JENIS
REGIONAL/ DYNAMIC
HOW WHERE
JENIS BATUAN CIRI KEJU- RUTERAAN
BATUAN METAMORFIK
PREEXISTING ROCKS
T, P, CHEMICAL FLUIDS
LINEATION
TEXTURE
FOLIATION
CHANGES
MINERALOGY
NONFOLIATED
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• Metamorphism means "changed form (berubah
  bentuk)

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Kitar batuan (Rock cycle)
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CYCLE
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Batuan Metamorfik terjadi hasil drpd perubahan
suhu, tekanan dan bendalir kimia

• Agents of Metamorphism
• Changes occur because of
• Heat
• Pressure
• Chemical fluids

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Perubahan suhu Geothermal gradient

• Temperature increases with depth at a rate of 20
  - 30 degrees C per km in the crust.Ultimate
  source of the heat? Radioactive decay. Increase
  of temperature and pressure with depth causes
  Regional Metamorphism (Metamorfisme Rantau)Heat
  may come from large bodies of molten rock rising
  under a wide geographic area.

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Metamorfisme sentuh

• Intrusions of hot magma can bake rocks as it
  intrudes them. Lava flows can also bake rocks on
  the ground surface. Lava or magma in contact with
  other rock causes Contact Metamorphism.
• Hornfels is a common contact metamorphic rock.

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CONTACT
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Contact metamorphism
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Contact metamorphism
Contact metamorphism along a narrow (approx. 1
meter wide) diabase dike in the Deep River Basin
of North Carolina. Diabase weathers tan. Contact
metamorphic aureole rocks (hornfels) are gray.
Host rocks are red siltstones
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Metamorfisme Rantau

• Pressure
• Burial Pressure. Pressure increases with depth
  due to the weight of the overlying rocks. A cubic
  foot of granite weighs 167.9 pounds. Increase of
  pressure and temperature with depth causes
  Regional Metamorphism. Regional metamorphism
  occurs at depths of 5 - 40 km.
• Tectonic pressures associated with convergent
  plate boundaries and continental collision also
  cause Regional Metamorphism.
• Pressure along fault zones causes Dynamic
  Metamorphism, the crushing and ductile flow of
  rock. Rocks formed along fault zones are called
  mylonites

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REGIONAL
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Continental collision
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SUBDUCTION
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3 Chemical Fluids

• In some metamorphic settings, new materials are
  introduced by the action of hydrothermal
  solutions (hot water with dissolved ions). Many
  metallic ore deposits form in this way.
• Hydrothermal solutions associated with magma
  bodies
• Black smokers - Sea water percolates through
  newly formed oceanic crust, dissolving out
  metallic sulfide minerals. The hot sea water
  rises along fractures and pours from vents in the
  seafloor as black clouds of dark mineral-rich
  water. Sulfide minerals (such as pyrite,
  sphalerite, and galena) and copper precipitate
  when the hot water comes in contact with cold sea
  water

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HYDROTHERMAL
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How do rocks change?

• Metamorphism causes changes in
• 1 Texture (definition shape, size and
  orientation of mineral grains in the rocks)
• 2 Mineralogy (chemical composition)

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STRESS
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FOLIATION
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FOLIATION
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STRESS
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FOLIATED
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Foliasi
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Texture

• The processes of compaction and recrystallization
  change the texture of rocks (shape, size and
  orientation) during metamorphism.
• Compaction The grains move closer
  together. The rock becomes more
  dense. Porosity is reduced. Note this is
  engineering parameter
• Example clay to shale to slate

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• RecrystallizationGrowth of new crystals. No
  changes in overall chemistry. New crystals grow
  from the minerals already present. A preferred
  orientation of minerals commonly develops under
  applied pressure. Platy or sheet-like minerals
  such as muscovite and biotite become oriented
  perpendicular to the direction of force. This
  preferred orientation is called foliation.

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Metamorphic Textures

• Foliation is a broad term referring to the
  alignment of sheet-like minerals. Types of
  foliation
• Schistosity - alignment of large mica flakes, as
  in a mica schist derived from the metamorphism of
  shale.
• Slaty cleavage - alignment of very fine-grained
  micas, as in a slate derived from the
  metamorphism of shale.
• Phyllitic structure - alignment of fine-grained
  micas, as in a phyllite.
• Gneissic banding - segregation of light and dark
  minerals into distinct layers in the rock, as in
  a gneiss

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Lineation

• refers to the alignment of elongated, rod-like
  minerals such as amphibole, pyroxene, tourmaline,
  kyanite, etc. Lineation is a texture commonly
  seen in the metamorphic rock amphibolite derived
  from the metamorphism of basalt

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Non-foliated or granular metamorphic rocks

• are those which are composed of equidimensional
  grains such as quartz or calcite. There is no
  preferred orientation. The grains form a mosaic.
  Examples quartzite derived from the metamorphism
  of quartz sandstone, and marble derived from the
  metamorphism of limestone or dolostone.

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• Note Not all quartzites and marbles are pure.
  Some contain impurities that were originally mud
  interlayered with or mixed with the original
  quartz sand or lime mud. These clay impurities
  metamorphose to layers of micas or other
  minerals, which may give marble (in particular) a
  banded, gneissic appearance, or which may give a
  slight foliation to some quartzites

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Foliated metamorphic rocks

• As shale is subjected to increasing grade of
  metamorphism (increasing temperatures and
  pressures), it undergoes successive changes in
  texture associated with an increase in the size
  of the mica grains

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Slate

• very fine grained rock. Resembles shale. Has
  slaty cleavage which may be at an angle to the
  original bedding. Relict bedding may be seen on
  cleavage planes. Often dark gray in color.
  "Rings" when you strike it. (Unlike shale, which
  makes a dull sound. Temperature about 200 degrees
  C Depth of burial about 10 km.

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slate
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Phyllite

• fine-grained metamorphic rock. Has a frosted
  sheen, resembling frosted eye shadow. This is no
  coincidence. Cosmetics commonly contain ground up
  muscovite (ground to a size similar to that
  occurring naturally in phyllite.)

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phyllite
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Schist

• metamorphic rock containing abundant obvious
  micas, several millimeters across. Several types
  of schist may be recognized, based on minerals
  which may be present
• mica schist
• garnet schist
• chlorite schist
• kyanite schist
• talc schist

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schist
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Gneiss

• (pronounced "nice") - a banded or striped rock
  with alternating layers of dark and light
  minerals. The dark layers commonly contain
  biotite, and the light layers commonly contain
  quartz and feldspar

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gneiss
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gneiss
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Migmatite

• a very high grade metamorphic rock that has been
  subjected to such high temperatures that it has
  partially melted. It is intermediate between the
  metamorphic and the igneous rocks. Look for
  swirled banding. The light colored minerals have
  undergone melting and flow. The dark colored
  minerals have been contorted by flow. Example -
  the Lithonia Gneiss in the area southeast of
  Atlanta

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migmatite
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non-foliated (and weakly foliated) metamorphic
rocks

• Marble - fizzes in acid because its dominant
  minerals is calcite (or dolomite). The parent
  rock is limestone (or dolostone).

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Marmar (Marble)
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Quartzite/kuarzit

• interlocking grains of quartz. Scratches glass.
  The rock fractures through the grains (rather
  than between the grains as it does in sandstone).
  The parent rock is quartz sandstone
• Hardest rock known
• UCS

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quartzite
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Others

• Metagraywacke - metamorphosed graywacke or "dirty
  sandstone".
• Metaconglomerate and stretched pebble
  metaconglomerate - the parent rock is
  conglomerate. The clasts are fairly easily
  recognized. May be more difficult to recognize if
  the clasts have been stretched

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Hornfels

• A fine-grained, tough, dense, hard, massive
  rock. Usually (but not always) dark in color.
  Finer grained than basalt, which it may
  superficially resemble. This rock forms through
  contact metamorphism. The parent rock is commonly
  siltstone or basalt, but may be other types of
  rock

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Serpentinite

• A dark green, dense, tough, massive, hard rack.
  May contain veins of asbestos. The parent rock is
  peridotite, an ultramafic rock
• ultramafic lack/low amount of SiO2, Fe, Mg
  (bandingkan dgn jadual pengelasan batuan igneus)

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serpentine
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Soapstone

• (sometimes called steatite) - a soft, easily
  carved rock with a slippery feel because it
  contains talc and chlorite. The parent rock is
  peridotite (ultramafic), probably with more water
  associated with it than in the formation of
  serpentinite. Example - Soapstone Ridge southeast
  of Atlanta

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Metabasalt

• (sometimes called greenstone if massive and
  green, or greenschist if foliated and green) -
  the green color comes from chlorite (soft and
  bluish green) and epidote (pea green). The parent
  rock is basalt. The grade of metamorphism is LOW

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Amphibolite

• Abundant amphibole is present may be lineated.
  Usually black. The parent rock is basalt. The
  grade of metamorphism is HIGH. Has been subjected
  to higher temperatures and pressures than
  metabasalt, greenstone, or greenschist.

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Mylonite

• A dynamic metamorphic rock which forms along
  fault zones

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mylonite
Mylonite along the Linville Falls Fault, Linville
Falls, NC. Relatively undeformed conglomeratic
quartzite lies above the layered mylonite zone
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Mineral changes in metamorphic rocks

• Recrystallization - rearrangement of crystal
  structure of existing minerals. Commonly many
  small crystals merge to form larger crystals,
  such as the clay in shale becoming micas in
  slate, phyllite, and schist. Note the chemical
  compositions of clay and muscovite.
• Also, fine-grained calcite in limestone
  recrystallizes to the coarse-grained calcite
  mosaic in marble

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Formation of new minerals

• there are a number of metamorphic minerals which
  form during metamorphism and are found
  exclusively (or almost exclusively) in
  metamorphic rocks
• Garnet - dark red dodecahedrons (12 sides)
• Staurolite - brown lozenge-shaped minerals,
  commonly twinned to form "fairy crosses". State
  mineral of Georgia

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garnet
Kegunaan?
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Kyanite

• sky blue bladed minerals with differential
  hardness. Scratch lengthwise with a knife or
  nail, but not sideways

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kyanite
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• Chlorite - dark bluish green, soft. Fe, Mg
• Talc - white or pale green and soft.
• Graphite - metamorphosed carbon
• Tourmaline - commonly black. Forms elongated
  crystals with a rounded triangular cross-section.
  Can see at Stone Mountain.
• Asbestos - fibrous mineral. Commonly light
  greenish. Occurs in veins (seems to fill a crack)
  with the fibers oriented perpendicular to the
  edged of the vein. Associated with lung diseases.
  Mesothelioma and asbestosis. Found in
  serpentinite. "Serpent rock" name due to
  snake-like veins of asbestos.
• Micas - muscovite (silvery), biotite (dark
  brown), phlogopite (light brown)

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Metamorphic index minerals

• Batuan metamorfik boleh digunakan sebagai tanda
  aras suhu dan tekanan dalam bumi
• In regional metamorphic terranes, the temperature
  and pressure regime is indicated by the
  distribution of metamorphic minerals across a
  large area. Low metamorphic grade (low
  temperatures and pressures) - about 200 degrees
  CSlate and phyllite
• chlorite
• muscovite
• biotite

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• Intermediate metamorphic grade
• Schist
• garnet
• staurolite

KOMPOSISI KIMIA?
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• High metamorphic grade - 800 degrees C (verging
  on melting)Gneiss and migmatite
• sillimanite
• Know which minerals are the metamorphic index
  minerals. Know which ones are characteristic of
  low, intermediate, and high metamorphic grades

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FACIES GRADE
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FACIES
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pandangan

• Jurutera bahan banyak menggunakan bahan ini
  untuk membuat bahan baru gt bahan termaju
  (advanced materials), composite materials,
  nanomaterials
• Keadaan makmal cuba disimulasikan seperti yang
  ditemui di dalam bumi
• sistem berbeza open vs closed

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Mineral yg terdapat pada zon metamorfik
REGIONAL
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foliation
Slate schist gneiss
texture
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Granular texture as in quartzite
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Changes that occur in the transformation to
become metamorphic rocks
Rumus
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ENGINEERING PROPERTIES

• POROSITY
• KEKUATAN EKAPAKSI (UCS)
• PERMEABILITY
• ABRASIVENESS

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HOW WHERE
CONTACT
METAMORFISME
JENIS
REGIONAL/ DYNAMIC
HOW WHERE
JENIS BATUAN CIRI KEJU- RUTERAAN
BATUAN METAMORFIK
PREEXISTING ROCKS
T, P, CHEMICAL FLUIDS
LINEATION
TEXTURE
FOLIATION
CHANGES
MINERALOGY
NONFOLIATED
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PHASE DIAGRAM FOR WATER
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