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UNDERSTANDING EARTH, SIXTH EDITION
GROTZINGER • JORDAN
GEOLOGY MEDIA SUITE
Chapter 6
Metamorphism
Modification of Rocks by
Temperature and Pressure
© 2010 W.H. Freeman and Company
The lithosphere and
asthenosphere interact to
metamorphose rock
Key Figure 6.3 (page 135)
Go to next slide to begin
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Shock
metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Regional
Shock
metamorphism metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Regional
Shock
metamorphism metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
high-pressure
metamorphism
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Regional
Shock
metamorphism metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
high-pressure
metamorphism
Contact
metamorphism
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Regional
Shock
metamorphism metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
high-pressure
metamorphism
Contact
metamorphism
Regional
metamorphism
Burial
metamorphism
Oceanic
crust
Oceanic
lithosphere
Regional
Shock
metamorphism metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
high-pressure
metamorphism
Contact
metamorphism
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Water
Burial
metamorphism
Regional
Shock
metamorphism metamorphism
Depth,
km
0
Con
tine
nta
35
l cr
Con
ust
tin
ent
al m
75
a nt
le l
ith
osp
As
her
the
e
no
sp
he
re
Regional
high-pressure
metamorphism
Contact
metamorphism
Regional
metamorphism
Oceanic
crust
Oceanic
lithosphere
Water
Burial
metamorphism
Seafloor
metamorphism
The lithosphere and asthenosphere
interact to metamorphose rock
Which kind of metamorphism is caused primarily by
increasing temperature with little change in pressure?
A. Regional Metamorphism
B. Contact metamorphism
C. Burial Metamorphism
D. Subduction-zone metamorphism
The lithosphere and asthenosphere
interact to metamorphose rock
Which kind of metamorphism is caused primarily by
increasing temperature with little change in pressure?
A. Regional Metamorphism
B. Contact metamorphism
C. Burial Metamorphism
D. Subduction-zone metamorphism
The lithosphere and asthenosphere
interact to metamorphose rock
High-pressure regional metamorphism is most closely
associated with which tectonic environment?
A. Continental rifting
B. Mid-ocean ridge
C. Subduction zone
D. Meteorite impact
The lithosphere and asthenosphere
interact to metamorphose rock
High-pressure regional metamorphism is most closely
associated with which tectonic environment?
A. Continental rifting
B. Mid-ocean ridge
C. Subduction zone
D. Meteorite impact
The lithosphere and asthenosphere
interact to metamorphose rock
Seafloor metamorphism that occurs at mid-ocean ridges
is caused by:
A. Directed pressure
B. Confining pressure
C. Metasomatism
D. All of the above
The lithosphere and asthenosphere
interact to metamorphose rock
Seafloor metamorphism that occurs at mid-ocean ridges
is caused by:
A. Directed pressure
B. Confining pressure
C. Metasomatism
D. All of the above
Texture, index minerals, grade,
and facies describe
metamorphism
Key Figure 6.4 (page 137)
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Increasing intensity of metamorphism
Low grade
Intermediate grade
Increasing crystal size
Increasing coarseness of foliation
High grade
Diagenesis
Slate
Slaty cleavage
Low grade Intermediate
grade
Phyllite
High grade
Schist
(abundant
micaceous
minerals)
Gneiss
(fewer
micaceous
minerals)
Migmatite
Schistosity
Banding
Banding
Foliated rocks are classified by the degree
of cleavage, schistosity, and banding.
Diagenesis
Slate
Slaty cleavage
Low grade Intermediate
grade
Phyllite
High grade
Schist
(abundant
micaceous
minerals)
Gneiss
(fewer
micaceous
minerals)
Migmatite
Schistosity
Banding
Banding
Texture, index minerals, grade,
and facies describe
metamorphism
Key Figure 6.7 (pages 142-143)
Go to next slide to begin
Canada
ME
NY
Isograds
VT
NH
Key:
MA
CT
RI
Low
grade
Medium
grade
High grade
Not
metamorphosed
Chlorite zone
Biotite zone
Garnet zone
Staurolite zone
Sillimanite zone
Index minerals define
metamorphic zones.
Canada
ME
NY
Isograds
VT
NH
Key:
MA
CT
RI
Low
grade
Medium
grade
High grade
Not
metamorphosed
Chlorite zone
Biotite zone
Garnet zone
Staurolite zone
Sillimanite zone
Index minerals define
metamorphic zones.
Isograds can be
used to plot the
degree of
metamorphism.
Canada
ME
NY
Isograds
VT
NH
Key:
MA
CT
RI
Low
grade
Medium
grade
High grade
Not
metamorphosed
Chlorite zone
Biotite zone
Garnet zone
Staurolite zone
Sillimanite zone
Inc
r
Pressure (kilobars)
Slate
eas
i ng
met
am
Intermediate
Grade
Phyllite
orp
hi c
gra
de
High
Grade
Schist
Blueschist
Gneiss
Migmatite
Temperature (°C)
Depth (km)
Low
Grade
Degree of metamorphism
Diagenesis
Low Intermediate
Greenschists
Amphibolites
High
Granulites
Chlorite
White mica (mainly muscovite)
Biotite
Garnet
Staurolite
Kyanite
Sillimanite
Albite (sodium plagioclase)
Degree of metamorphism
Diagenesis
Low Intermediate
Greenschists
Amphibolites
High
Granulites
Chlorite
White mica (mainly muscovite)
Biotite
Garnet
Staurolite
Kyanite
Sillimanite
Albite (sodium plagioclase)
With increasing metamorphic
grade, mineral composition
changes.
Degree of metamorphism
Diagenesis
Low Intermediate
Greenschists
Amphibolites
High
Granulites
Chlorite
White mica (mainly muscovite)
Biotite
Garnet
Staurolite
Kyanite
Sillimanite
Albite (sodium plagioclase)
With increasing metamorphic Mineral suites define
grade, mineral composition
metamorphic facies.
changes.
200
400
15
20
25
30
Eclogite
35
600
40
1000
Temperature (°C)
800
Depth (km)
10
Granulite
0
ne
n zo
uctio
15
20
Subd
13.5
Greenschist
10
5
Amphibolite
5
Contac
t meta
Con
morph
is m
mo ditio
u nt ns
ain ben
bel eath
ts
st
hi
sc
ue
Bl
Pressure (kilobars)
Ze
ol
ite
0
Hornfels
Partial melt
ing begins
0
200
15
20
25
30
Eclogite
35
600
40
1000
400
Temperature (°C)
Metamorphic facies correspond
to particular combinations of
pressure and temperature...
800
Depth (km)
10
Granulite
0
ne
n zo
uctio
15
20
Subd
13.5
Greenschist
10
5
Amphibolite
5
Contac
t meta
Con
morph
is m
mo ditio
u nt ns
ain ben
bel eath
ts
Partial melt
ing begins
Ze
ol
ite
0
Hornfels
st
hi
sc
ue
Bl
Pressure (kilobars)
0
200
15
20
25
Depth (km)
10
Granulite
0
ne
n zo
uctio
15
20
Subd
13.5
Greenschist
10
5
Amphibolite
5
Contac
t meta
Con
morph
is m
mo ditio
u nt ns
ain ben
bel eath
ts
Partial melt
ing begins
Ze
ol
ite
0
Hornfels
st
hi
sc
ue
Bl
Pressure (kilobars)
0
30
Eclogite
35
600
40
1000
400
800
Temperature (°C)
Metamorphic facies correspond
to particular combinations of
pressure and temperature...
… and can be used
to indicate specific
tectonic environments.
Texture, index minerals, grade, and
facies describe metamorphism
How do crystal size and foliation change with increasing
intensity of metamorphism?
A. Grain size increases and foliation becomes less coarse.
B. Grain size decreases and foliation becomes coarser.
C. Both grain size and foliation coarseness decrease.
D. Both grain size and foliation coarseness increase.
Texture, index minerals, grade, and
facies describe metamorphism
How do crystal size and foliation change with increasing
intensity of metamorphism?
A. Grain size increases and foliation becomes less coarse.
B. Grain size decreases and foliation becomes coarser.
C. Both grain size and foliation coarseness decrease.
D. Both grain size and foliation coarseness
increase.
Texture, index minerals, grade, and
facies describe metamorphism
Which list places foliation textures in order of increasing
metamorphic grade (low grade to high grade)?
A. Slate, gneiss, phyllite, schist
B. Slate, phyllite, schist, gneiss
C. Gneiss, schist, slate, phyllite
D. Gneiss, phyllite, schist, slate
Texture, index minerals, grade, and
facies describe metamorphism
Which list places foliation textures in order of increasing
metamorphic grade (low grade to high grade)?
A. Slate, gneiss, phyllite, schist
B. Slate, phyllite, schist, gneiss
C. Gneiss, schist, slate, phyllite
D. Gneiss, phyllite, schist, slate
Texture, index minerals, grade, and
facies describe metamorphism
Metamorphic facies are defined by:
A. Suites of minerals
B. Foliation textures
C. Pressures and temperatures
D. Tectonic environments
Texture, index minerals, grade, and
facies describe metamorphism
Metamorphic facies are defined by:
A. Suites of minerals
B. Foliation textures
C. Pressures and temperatures
D. Tectonic environments
Texture, index minerals, grade, and
facies describe metamorphism
Which metamorphic facies is characteristic of contact
metamorphism?
A. Greenschist facies
B. Blueschist Facies
C. Eclogite facies
D. Hornfels facies
Texture, index minerals, grade, and
facies describe metamorphism
Which metamorphic facies is characteristic of contact
metamorphism?
A. Greenschist facies
B. Blueschist Facies
C. Eclogite facies
D. Hornfels facies
Pressure-Temperature Paths
In most situations, prograde metamorphism at plate
boundaries begins with the metamorphic rock _______.
A. basalt
B. schist
C. gniess
D. slate
Pressure-Temperature Paths
In most situations, prograde metamorphism at plate
boundaries begins with the metamorphic rock _______.
A. basalt
B. schist
C. gniess
D. slate
Pressure-Temperature Paths
Retrograde metamorphism describes the process by
which:
A. metamorphic rocks are formed
B. metamorphic rocks are returned back to the surface
C. a high-grade metamorphic rock can be turned into a lowgrade metamorphic rock
D. the mineral kyanite is formed
Pressure-Temperature Paths
Retrograde metamorphism describes the process by
which:
A. metamorphic rocks are formed
B. metamorphic rocks are returned back to the
surface
C. a high-grade metamorphic rock can be turned into a lowgrade metamorphic rock
D. the mineral kyanite is formed
Pressure-Temperature Paths
Which conditions are most likely associated with
metamorphism at a convergent boundary between two
continental plates?
A. high temperature and low pressure
B. low temperature and high pressure
C. high temperature and pressure
D. low temperature and pressure
Pressure-Temperature Paths
Which conditions are most likely associated with
metamorphism at a convergent boundary between two
continental plates?
A. high temperature and low pressure
B. low temperature and high pressure
C. high temperature and pressure
D. low temperature and pressure
Pressure-Temperature Paths
The metamorphic rock blueschist forms in high-pressure
and low-temperature prograde metamorphic
environments consistent with:
A. subduction zones
B. continent-continent collisional boundaries
C. divergent plate boundaries
D. hot-spot volcanism
Pressure-Temperature Paths
The metamorphic rock blueschist forms in high-pressure
and low-temperature prograde metamorphic
environments consistent with:
A. subduction zones
B. continent-continent collisional boundaries
C. divergent plate boundaries
D. hot-spot volcanism
Pressure-Temperature Paths
What type of metamorphic rock would result from the
complete melting of the metamorphic rock migmatite?
A. blueschist
B. marble
C. conglomerate
D. all of these are equally likely
E. none of these, an igneous rock would result
Pressure-Temperature Paths
What type of metamorphic rock would result from the
complete melting of the metamorphic rock migmatite?
A. blueschist
B. marble
C. conglomerate
D. all of these are equally likely
E. none of these, an igneous rock would result