1. Classification and Facies Wikipedia

2. Today Updates: Not today Lecture outline: - Rock classification - Facies

3. Prograde Metamorphism Normally progress through series of mineral assemblages, for example:Normally progress through series of mineral assemblages, for example: 1.epidote, chlorite, andalusite, muscovite, quartz, k-spar, and albite 2.sillimanite, plagioclase, cordierite, muscovite, quartz and k-spar 3.sillimanite, plagioclase, cordierite, quartz, and k-spar

4. Prograde Retrograde Prograde Metamorphism

5. Retrograde Metamorphism Prograde Retrograde http://www.und.nodak.edu/instruct/mineral/ 320petrology/opticalmin/chlorite.htm

6. Common Prograde Sequence Index minerals make zones: s s Chlorite zone. Pelitic rocks are slates or phyllites and typically contain chlorite, muscovite, quartz and albite s s Biotite zone. Slates give way to phyllites and schists, with biotite, chlorite, muscovite, quartz, and albite s s Garnet zone. Schists with conspicuous red almandine garnet, usually with biotite, chlorite, muscovite, quartz, and albite or oligoclase s s Staurolite zone. Schists with staurolite, biotite, muscovite, quartz, garnet, and plagioclase. Some chlorite may persist s s Kyanite zone. Schists with kyanite, biotite, muscovite, quartz, plagioclase, and usually garnet and staurolite s s Sillimanite zone. Schists and gneisses with sillimanite, biotite, muscovite, quartz, plagioclase, garnet, and perhaps staurolite. Some kyanite may also be present (although kyanite and sillimanite are both polymorphs of Al 2 SiO 5 )

7. Sequence of indicator mineralsChlorite Biotite Garnet Staurolite Kyanite Sillimanite

8. Types of Protolith Six chemically based-groups to start with 1. Ultramafic - very high Mg, Fe, Ni, Cr 2. Mafic - high Fe, Mg, and Ca 3. Shales (pelitic) - high Al, K, Si 4. Carbonates- high Ca, Mg, CO 2 5. Quartz - nearly pure SiO 2. 6. Quartzo-feldspathic - high Si, Na, K, Al

9. A Classification of Metamorphic Rocks

11. Compositional Classification ParentMetamorphic rock Clay-rich sedimentpelite Sand-rich sedimentpsammite Clay-sand mixsemi-pelite Quartz sandquartzite Marl (limy mud)metamarls-silicate/calcareous Limestonemarble Basaltmetabasite

12. a b Pelite protolith: Foliated Metamorphic Rocks -- low grade

13. Pelite protolith: Foliated Metamorphic Rocks --middle grade

14. Pelite protolith: Foliated Metamorphic Rocks -- high grade

15. Non-Foliated Rocks

16. Specific Rock Types

17. Skarn: carbonate + contact metamorphism + Si added (metasomatism). Minerals: grossular, epidote, tremolite, wollastonite, diopside Granulite: high-grade rock from pelitic, mafic, or quartzo-feldspathic protolith, few OH-bearing minerals. few OH-bearing minerals. Specific Rock Types

18. http://z.about.com/d/geology/1/0/I/z/migmatite1_500.jpg http://www.earth.edu.waseda.ac.jp/photogeology/ 200504rocky/BigornMtS/1K_DSC_1687.jpg

19. Protolith = mafic rock or graywacke (dirty sst): Greenschist: low-grade, contains chlorite, actinolite, epidote (all green), and albite. Amphibolite: mid-grade, dominated by hornblende + plagioclase. Specific Rock Types http://z.about.com/d/geology/1/0/h/L/greenschist.jpg

20. Serpentinite: ultramafic rock, low-grade metamorphosed. Blueschist: high-P, blue by glaucophane--amphibole (mafic rock) or blue by kyanite (pelite). Eclogite: green + red due to clinopyroxene and garnet (omphacite + pyrope). (basalt) Specific Rock Types http://www.npolar.no/geonet/picture_atlas/SE02-1-25.jpg http://www.dges.tohoku.ac.jp/museum/large/eclogite.jpg

21. Metamorphic Facies Wikipedia

22. Prograde Sequence and Facies Index minerals make zones, but COMPOSITION DEPENDENT Change in composition, means change in minerals occurring s Chlorite zone. s Biotite zone. s Garnet zone. s Staurolite zone. s Kyanite zone. s s Sillimanite zone. => Facies is better to compare different metamorphic rocks F Chlorite F Biotite F Cordierite F Andalusite F Sillimanite

23. Prefix and mineral texture

24. High Strain Rocks

26. Why do we care about metamorphic rocks?