1. Metamorphic Rocks

2. The Rock Cycle If you bury a rock deep enough, it will melt (IGNEOUS) Not so deep, a rock will become lithified (SEDIMENTARY) At conditions (Pressures and Temperatures) just right, metamorphism occurs

3. http://voyagerstories.files.wordpress.com/2009/02/rock-cycle.jpg

4. What does “metamorphic” mean? “Meta” = after “Morph” = change in form So Metamorphic rocks are rocks that have changed from their original state.

5. How do they change? Change in size Change in shape Change in minerals (sometimes)

6. How does metamorphism happen? Increase in Temperature (T) –Increase in depth = increase in T Increase in Pressure (P) –Increase in depth = increase in P Hydrothermal fluids that are rich in ions that can make new minerals

7. http://www.jamstec.go.jp/chikyu/image_files/C00.jpg

8. Where does metamorphism occur? Two main types 1) REGIONAL METAMORPHISM –Mountain building (subduction of plates = compression) Intense pressures Happens over large regions (for instance, several states) http://www.emporia.edu/earthsci/student/geller2/subduction.jpg

9. Regional Metamorphism: Triumph, SW Face, J Scurlock

10. Where does metamorphism occur? 2) CONTACT METAMORPHISM –Metamorphism in contact with a batholith –the igneous intrusion will “bake” the rocks it comes in contact with Happens over a much smaller area than regional metamorphism http://www.windows.ucar.edu/earth/geology/images/meta_contact2.gif

11. Contact Metamorphism, http://www.geol.umd.edu/~jmerck/geol100/lectures/16.html

12. Hey WAKE UP! This is COOL!

13. How does metamorphism work? Heat Heat is the most important factor increased heat = increased kinetic Energy = increased chemical reactions = REMINERALIZATION (This is NOT melting! This is NOT melting!)

14. Remineralization (Metamorphism) This rock was originally a shale, but has been subjected to HEAT and pressure to form slate (sedimentary  metamorphic) M. Miller

15. How does metamorphism work? Pressure Pressure will confine the rock in one or more directions Causes an alignment of flat minerals At its most intense, can cause “zonation” of mafic and felsic minerals

16. What was the direction of greatest P? http://sorrel.humboldt.edu/~jdl1/web.page.images/rocks/r_8.gif

17. Gneiss Central WI, M Miller

18. What can you say about this rock? M. Miller

19. 3 Terms you need to know 1) Protolith –The “parent” rock of a metamorphic rock (what it was before it metamorphosed) –Proto = “earliest form of” –Lith = rock

20. 3 Terms you need to know 2) Grade –Low grade = low P and T –High grade = high P and T

21. 3 Terms you need to know 3) Foliation –Sheets upon sheets upon sheets As in schist (can be called schistosity) DUDE! We can also say a metamorphic rock is nonfoliated!

22. Protolith: sedimentary rock: shale (mudstone) L to R (low grade to high grade) –Slate (low grade) –Phyllite –Schist (foliated) –Gneiss (high grade) M. Miller

23. Protolith: Igneous rock Granite High grade –Granite goes to gneiss –(If you want to be really cool, you would call this an orthogneiss) –your choice –What is that red mineral? –Is this foliated?

24. Protolith: sedimentary: Quartz sandstone Quartzite Foliated?

25. Protolith: Sedimentary: Limestone Marble Foliated?