Metamorphic Petrology noted

1. Introduction to Metamorphic Petrology
Recommended Textbook: J.D. Winter (2001)
An Introduction to Igneous and Metamorphic
Petrology: Prentice Hall Pub.

2. Scope of Metamorphic petrology
 Metamorphic petrology is the study of the subsolidus
changes that a rock undergoes when exposed to
physicochemical conditions different from those prevailing
near the surface of the Earth.
 Metamorphism produces changes in mineral assemblages
and textures that reflect re-equilibration of the rock to the
new physicochemical conditions, i.e., minimization of the
energy of the system.
Metamorphism is commonly isochemical (except for
volatile components, e.g., H2O, CO2). Where the system is
open, the process is referred to as metasomatism.

3. Metamorphic Reactions
Dehydration
KAl3Si3O10(OH)2 + SiO2 = KAlSi3O8 + AlSi2O5 + H2O
Decarbonation
CaCO3 + SiO2 = CaSiO3 + CO2
Calcite Quartz Wollastonite
Muscovite Quartz K-Feldspar Sillimanite
Solid-Solid
NaAlSi3O8 = NaAlSi2O6 + SiO2
Albite Jadeite Quartz

4. Prograde and Retrograde Metamorphism
Prograde Path
Retrograde Path

5. Metamorphic Facies
 A metamorphic facies is a domain of
Pressure-Temperature Space
 Metamorphic facies are defined by
characteristic mineral assemblages specific
to particular bulk-rock compositions

6. Conditions of Metamorphism and
Metamorphic Facies

7.  Contact or Thermal Metamorphism
 Regional Metamorphism
 Orogenic Metamorphism
 Burial Metamorphism
 Ocean Floor Metamorphism
 Hydrothermal Metamorphism
(Alteration)
 Impact or Shock Metamorphism
Types of Metamorphism

8. Contact or Thermal Metamorphism

9. Contact Metamorphism of Limestone
Diabase
Marble
Limestone
Marble
Limestone

10. Pyroxene
Plagioclase
Garnet
Thermally Metamorphosed Clastic Sediments

11. Orogenic Metamorphism

12. Orogenic Metamorphism

13. Orogenic Metamorphism and differential stress
 s1 > s2 = s3  foliation and no lineation
 s1 = s2 > s3  lineation and no foliation
 s1 > s2 > s3  both foliation and lineation
s1
Foliation (or Cleavage) and Lineation

14. Onset of Orogenic Metamorphism
Shale Slate

15. Phyllite Schist
Progressive Orogenic Metamorphism

16. Progressive Orogenic Metamorphism
Gneiss

17. Anatexis

18. Anatexis or Partial Melting of Metasedimentary
Rocks (Migmatites)

19. Burial Metamorphism

20. Burial Metamorphism

21. Subduction Metamorphism

22. Paired Metamorphic Belts
Blueschist Facies
Amphibolite Facies

23. Subduction Metamorphism

24. Ocean Floor Metamorphism

25. Ocean Floor Metamorphism

26. Metamorphic Isograd Mapping (Index Minerals)

27. Metamorphic
Index Minerals
(Porphyroblasts)
Staurolite
(Fe,Mg)2Al9Si4O23(OH) Garnet
(Fe,Mg)3Al2Si3O12
Cordierite
(Mg,Fe)2Al4Si5O18

28. The Aluminosilicates Al2SiO5
Andalusite Kyanite
Sillimanite
Sillimanite

29. Metamorphic Isograds and P-T Paths
Barrow Zones Buchan Zones

30. Aluminosilcates as Indicators of
Metamorphic Grade

31. Metamorphic reactions and metamorphic grade
Muscovite + Quartz = K-feldspar + sillimanite + H2O
Sillimanite
Quartz
K-feldspar
Muscovite

32. Oslo: K-Feldspar- Cordierite Orijärvi: Biotite-muscovite
2 KMg3AlSi3O10(OH)2 + 6 KAl2AlSi3O10(OH)2 (Ms) + 15 SiO2
= 3 Mg2Al4Si5O18 + 8 KAlSi3O8 + 8 H2O
Metamorphic Facies and Isograds

33. Facies Series

34. Pressure-Temperature-Time Paths