metamorphic rocks metamorphic rocks form from...
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Minerals and
Minerals and
Metamorphic Rocks
Metamorphic Rocks
Lecture 10
Lecture 10
Metamorphic Rocks
Metamorphic Rocks
��Metamorphic rocks form
from pre
Metamorphic rocks form
from pre-- existing
existing
rocks
rocks
��Metamorphic rocks change with increasing
Metamorphic rocks change with increasing
temperature (and pressure to a lesser
temperature (and pressure to a lesser
extent)
extent)
��Minerals in m
etamorphic rocks will depend
Minerals in m
etamorphic rocks will depend
both on composition and m
etamorphic
both on composition and m
etamorphic
grade
grade
Typical Composition of Rocks
Typical Composition of Rocks
0.05
0.05
0.24
0.24
3.96
3.96
4.30
4.30
1.10
1.10
0.34
0.34
KK22OO
0.03
0.03
0.07
0.07
1.13
1.13
3.55
3.55
2.91
2.91
0.49
0.49
Na
Na22OO
32.87
32.87
53.06
53.06
3.50
3.50
1.14
1.14
9.47
9.47
5.05
5.05
CaO
CaO
21.88
21.88
1.59
1.59
2.82
2.82
0.39
0.39
6.73
6.73
31.24
31.24
MgO
MgO
0.05
0.05
0.07
0.07
0.25
0.25
0.06
0.06
0.20
0.20
0.41
0.41
MnO
MnO
0.60
0.60
1.15
1.15
5.69
5.69
1.59
1.59
10.92
10.92
11.19
11.19
FeO
FeO
0.13
0.13
0.98
0.98
17.00
17.00
13.27
13.27
15.74
15.74
4.23
4.23
AlAl 22OO33
0.41
0.41
3.64
3.64
64.70
64.70
72.82
72.82
49.20
49.20
42.26
42.26
SiOSiO
22
Dolostone
Dolostone
Limestone
Limestone
Shale
Shale
Granite
Granite
Gabbro
Gabbro
Peridotite
Peridotite
What ele
ments
are
ES
SE
NTIA
L to d
escribe e
ach rock?
Typical Composition of Rocks
Typical Composition of Rocks
0.05
0.05
0.24
0.24
3.96
3.96
4.30
4.30
1.10
1.10
0.34
0.34
KK22OO
0.03
0.03
0.07
0.07
1.13
1.13
3.55
3.55
2.91
2.91
0.49
0.49
Na
Na22OO
32.87
32.87
53.06
53.06
3.50
3.50
1.14
1.14
9.47
9.47
5.05
5.05
CaO
CaO
21.88
21.88
1.59
1.59
2.82
2.82
0.39
0.39
6.73
6.73
31.24
31.24
MgO
MgO
0.05
0.05
0.07
0.07
0.25
0.25
0.06
0.06
0.20
0.20
0.41
0.41
MnO
MnO
0.60
0.60
1.15
1.15
5.69
5.69
1.59
1.59
10.92
10.92
11.19
11.19
FeO
FeO
0.13
0.13
0.98
0.98
17.00
17.00
13.27
13.27
15.74
15.74
4.23
4.23
AlAl 22OO33
0.41
0.41
3.64
3.64
64.70
64.70
72.82
72.82
49.20
49.20
42.26
42.26
SiOSiO
22
Dolostone
Dolostone
Limestone
Limestone
Shale
Shale
Granite
Granite
Gabbro
Gabbro
Peridotite
Peridotite
2
Essential Components of Rocks
Essential Components of Rocks
CaO
CaO
KK22OO
CaO
CaO
CaO
CaO
KK22OO
CaO
CaO
FeO
FeO
Na
Na22OO
FeO
FeO
MgO
MgO
MgO
MgO
Al
Al 22OO33
Al
Al 22OO33
Al
Al 22OO33
FeO
FeO
SiOSiO
22SiOSiO
22SiOSiO
22SiOSiO
22SiOSiO
22
Carbonate
Carbonate
Rock
Rock
Shale
Shale
Granite
Granite
Gabbro
Gabbro
Peridotite
Peridotite
Chemographic
Chemographic
Analysis:
Analysis:
SiO
SiO
22-- C
aO
CaO-- M
gO Diagrams
MgO Diagrams
Chemographic
Chemographic
Analysis:
Analysis:
ACF Diagrams
ACF Diagrams
Chemographics
Chemographics
��What minerals (pink dots) would you need to have to in a
What minerals (pink dots) would you need to have to in a
rock with composition X? Y?
rock with composition X? Y?
Fig. 26-12.From W
inter (2001) An
Introduction to Igneous and
Metamorphic Petrology. Prentice
Hall.
Y
3
Chemographic
Chemographic
Analysis:
Analysis:
SiO
SiO
22-- C
aO
CaO-- M
gO Diagrams
MgO Diagrams
“Rock A”
What m
inera
ls m
ight you fin
d in a
rock w
ith c
om
positio
n “A
”?
Chemographic
Chemographic
Analysis:
Analysis:
SiO
SiO
22-- C
aO
CaO-- M
gO Diagrams
MgO Diagrams
What m
inera
ls m
ight you fin
d in a
rock w
ith c
om
positio
n “B
”?
“Rock B”
Chemographic
Chemographic
Analysis:
Analysis:
ACF Diagrams
ACF Diagrams
What m
inera
ls m
ight you fin
d in a
rock w
ith c
om
positio
n “C
”?
Rock C
Chemographic
Chemographic
Analysis
Analysis
��There can be m
any combinations of
There can be m
any combinations of
minerals for a given rock composition that
minerals for a given rock composition that
are
are chemographically
chemographically
allowable
allowable……
��A
re they a
ll pro
bable
, or even p
ossib
le?
Are
they a
ll pro
bable
, or even p
ossib
le?
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General Rules of Metamorphism
General Rules of Metamorphism
��Metamorphism is
Metamorphism is isochemical
isochemicalwith respect
with respect
to non
to non-- volatile components
volatile components
��Most metamorphic reactions liberate
Most metamorphic reactions liberate
volatiles (H
volatiles (H
22O and CO
O and CO
22))
��The m
inerals in low
The m
inerals in low-- grade m
etamorphic rocks
grade m
etamorphic rocks
have m
ore volatiles than high
have m
ore volatiles than high-- grade
grade
metamorphic rocks
metamorphic rocks
��e.g., m
icas
e.g., m
icas ��
amphiboles
amphiboles ��
pyroxenes
pyroxenes
Chemographic
Chemographic
Analysis:
Analysis:
ACF Diagrams
ACF Diagrams
Petrogenetic G
rids
Petrogenetic G
rids
��PP-- T diagrams for multicomponent systems that
T diagrams for multicomponent systems that
show a set of reactions, generally for a specific
show a set of reactions, generally for a specific
rock type
rock type
Petrogenetic grid
for mafic rock
s
Fig. 26
Fig. 26-- 19.
19.Sim
plified petrogenetic grid for metamorphosed m
afic rocks showi
Sim
plified petrogenetic grid for metamorphosed m
afic rocks showi ng the location of several determined
ng the location of several determined
univariant reactions in the CaO
univariant reactions in the CaO-- M
gO
MgO-- A
lAl 22OO
33-- SiO
SiO
22-- HH
22OO-- (Na
(Na22O) system
(O) system
(““C(N
)MASH
C(N
)MASH””).
). W
inter (2001) An
Winter (2001) An
Introduction to Igneous and M
etamorphic Petrology. Prentice H
all
Introduction to Igneous and M
etamorphic Petrology. Prentice H
all..
5
Progressive M
etamorphism of
Progressive M
etamorphism of Metabasites
Metabasites
Chemographic
Chemographic
Analysis:
Analysis:
SiO
SiO
22-- C
aO
CaO-- M
gO Diagrams
MgO Diagrams
Progressive M
etamorphism of
Progressive M
etamorphism of Peridotites
Peridotites
Progressive M
etamorphism of Carbonate Rocks
Progressive M
etamorphism of Carbonate Rocks
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Progressive M
etamorphism of Carbonate Rocks
Progressive M
etamorphism of Carbonate Rocks
Progressive M
etamorphism of
Progressive M
etamorphism of Peridotites
Peridotites
Chemographic
Chemographic
Analysis:
Analysis:
AFM D
iagrams
AFM D
iagrams
FeO
K2O
MgO
Al 2O
3
Progressive M
etamorphism of Pelitic Rocks
Progressive M
etamorphism of Pelitic Rocks