Part 1. Overview of Metamorphism and Tectonics
Part 2. Introduction to Metamorphism
Part 3. Physical Processes of Metamorphism
Part 4. Introductory Phase Equilibria and Thermodynamics
Part 5. Ultramafic Rocks
Part 6. Mafic Rocks
Part 7. Pelitic Rocks
Part 8. Diffusion
Part 9. Thermobarometry
Part 10. Kinetics
Part 11. Interaction Between Metamorphism and Deformation
Part 12. Metamorphism and Geochronology
Part 13. Metamorphism and Tectonics I
Part 14. Metamorphism and Tectonics II
Thermodynamics Notes

Part 3. Physical Processes that Cause Metamorphism

Read Chapters 21-24 of Igneous and Metamorphic Petrology by John Winter or Chapters 5 & 16 of Igneous and Metamorphic Petrology by Philpotts

Temperature

Pressure

where is density, g the acceleration of gravity, and z depth.

materialdensity (g/cm3)density (kg/m3)
water 1 1000
sedimentary rock 2.7 2700
mafic rock 3.0 3000
upper mantle 3.3 3300

e.g., what is the pressure at the base of a 10 km column of ultramafic rock?
= 3,300 kg/m3 * 10 m/s2 * 10,000 m
= ~3.3E8 kg m s-2 m-3 m
= 3.3E8 N/m2 (recall that N = kg m s-2)
= 3.3E8 Pa (recall that Pa = N/m2)
= 330 MPa (=3 kbar)


Rates of Exhumation
processdz/dt (mm/a or km/Ma)
burial by sedimentation 0.01 —> 1
'burial' by subduction 10 —> 100
erosional exhumation -0.1 —> -10
tectonic exhumation -10 —> -100

Data on the rate of erosional exhumation:

Metamorphic Facies

A metamorphic facies is a set of metamorphic mineral assemblages (parageneses), each for a specific rock compositions, that form over a specific range of P and T. The metamorphic facies are defined for mafic rocks. You should memorize the following simple form of the facies diagram:

For those interested in more detail, consult this diagram:

faciesmineralsnotes
basalt and gabbro protoliths plagioclase NaAlSi3O8-CaAl2Si2O8 + pyroxene CaSiO3-MgSiO3-FeSiO3 .
zeolite facies common zeolites: laumontite, wairakite, analcime (Na,Ca)AlSiO(OH)x zeolites: channel structure makes them useful for engineering
common textures: in cracks, alteration of feldspar or glass
greenschist facies albite + epidote + actinolite + chlorite + quartz
albite NaAlSi3O8 takes up Na, Al, Si
epidote CaAlSiO(OH)x takes up Ca
actinolite Ca2(Fe,Mg)5Si8O22(OH)2 takes up Fe, Mg
chlorite (Mg,Fe)(AlSi)O(OH)x
.
albite-epidote amphibolite facies albite + epidote + hornblende + quartz

albite NaAlSi3O8 takes up Na, Al, Si
epidote CaAlSiO(OH)x takes up Ca
hornblende (K,Na)(Ca,Fe,Mg)(AlSi)O22(OH)2
modal proportion of albite decreases, Na enters amphibole
modal proportion of chlorite decreases, Fe + Mg enters amphibole
amphibolite facies plagioclase + hornblende + quartz epidote replaced by intermediate plagioclase
remainder of elements in hornblende
granulite facies orthopyroxene + clinopyroxene + plagioclase + quartz must have 2 pyroxenes; can also have hornblende or garnet
blueschist facies glaucophane Na2Mg3Al2Si8O22(OH)2
lawsonite or epidote CaAlSiO(OH)x
high P, low T
eclogite facies omphacite (Na,Al,Mg,Fe)Si2O6
garnet (Ca,Mg,Fe,Mn)3Al2Si3O12
high P, high T
coesite-eclogite facies coesite SiO2
diamond C
majorite Mg4Si4O12
extreme pressure

Granulites look a lot like igneous rocks:

Eclogites consist mostly of two minerals: garnet and Na-rich clinopyroxene known as omphacite:

Link Between Elements and Minerals

Nine common mineral-forming elements
elementmineral
Si silicates
Al most silicates
Fe + Mg ferro-magnesian minerals
Ca feldspar or epidote
Na feldspar or jadeite
K mica or K-feldspar
O most minerals
H hydrous minerals



Next most common mineral-forming elements
elementmineral
P + Y + Ce apatite, xenotime, monazite
S sulfide minerals
Ti sphene, rutile, and ilmenite
Cr amphibole, chromite
Mn amphibole
Co + Ni olivine
Zn + Li staurolite
Sr carbonate minerals, feldspars
Zr + Hf + U + Pb zircon



Part 1. Overview of Metamorphism and Tectonics
Part 2. Introduction to Metamorphism
Part 3. Physical Processes of Metamorphism
Part 4. Introductory Phase Equilibria and Thermodynamics
Part 5. Ultramafic Rocks
Part 6. Mafic Rocks
Part 7. Pelitic Rocks
Part 8. Diffusion
Part 9. Thermobarometry
Part 10. Kinetics
Part 11. Interaction Between Metamorphism and Deformation
Part 12. Metamorphism and Geochronology
Part 13. Metamorphism and Tectonics I
Part 14. Metamorphism and Tectonics II
Thermodynamics Notes