1. H.W. #3 + Read Solar Nebula Theory Study Guide for exam 2 Study Area for lab has practice exam All missed labs must be made up before lab exam All missed homework must be made up before lecture exam 2

2. Practice Lab Exam Lab Samples Study Area Felmley Hall 203

3. Metamorphism and Metamorphic Rocks

4. Rock Cycle Revisited Sedimentary Rocks Igneous Rocks Metamorphic Rocks Magma Sediment Pressure And Cementation Erosion Heat and Pressure Cooling Heat Pressure Erosion

5. Igneous Aphanitic -glassy -vesicular Phaneritic Sedimentary Nonclastic -biochemical (biogenic) -chemical Clastic Metamorphic Foliated -banded Nonfoliated Rock Textures

6. Definitions Metamorphism – mineralogical, chemical, and physical changes that occur in solid rocks. Occurs at depths greater than that of sediments and sedimentary rocks Solid state recrystallization – changes that occur without the rock melting (rocks that melt are igneous).

7. Surface 5 km 30 km 200 o C 600 o C Sedimentary Metamorphic Magma 15 o C

8. Factors influencing Metamorphism Temperature Pressure Pore Fluid Time

9. Temperature, Pressure and Rock Type

10. Factors influencing Metamorphism Temperature below about 200 o C, most minerals are stable (little or no metamorphism) above 200 o C, reaction rate increases as temperature increases, new minerals begin to form above 600 o C, some minerals begin to melt (transition to igneous rocks)

11. Factors influencing Metamorphism Pressure as pressure increases, pore spaces reduced and density increases, pore fluids are expelled Differential stress pressure is greater in one direction than in another

12. Differential Stress

13. Effects of Stress Uniform Differential

14. Differential Stress Foliation – a metamorphic rock texture due to alignment of minerals as a result of differential stress Slaty cleavage – foliation that develops at low temperature and pressure (metamorphosed shale)

15. Foliation In this schist, viewed between crossed polarisers, the parallel mica flakes show up in bright colors, and large rounded garnet crystals appear black. Field of view 6 mm, polarising filters.

16. Burial Mountain Building

18. Factors influencing Metamorphism Pore fluids (water and carbon dioxide) as pressure increases, pore fluids are expelled Pore fluids increase the rate of metamorphic reactions by: storing ions involved in reactions moving ions from one place to another

19. Pore Fluids Dissolution / Precipitation

20. Factors influencing Metamorphism Time solid state recrystallization is a slow process in general, size of minerals increases with time

21. Preferred Mineral Orientation (Foliation) Ductile (plastic) Deformation Pressure Solution Grain Rotation Growth in Preferred Orientation

22. Ductile (plastic) DeformationPressure Solution

23. Grain Rotation

24. Growth in Preferred Orientation

25. Foliation

26. Types of Metamorphism 1. Burial Metamorphism 2. Regional Metamorphism 3. Contact Metamorphism

27. Types of Metamorphism Burial Metamorphism most common type, occurs where crust is greater than 5 km thick Relatively low temp. and pres. at shallow depths through High Temp. and Press at great depths Maximum stress vertical, foliation parallel to ground surface

28. Burial Metamorphism

29. Regional Metamorphism

30. Types of Metamorphism Regional Metamorphism associated with convergent plate margins folding and faulting increase thickness of the crust occurs over a range of temperatures and pressures low grade to high grade metamorphism

32. Grades of Regional Metamorphism

33. Shale sedimentary rock Slate – aligned clay minerals Phyllite – muscovite mica Schist - Biotite mica/ garnet Gniess – quartz/ feldspar (banded) Melting Increasing Hot & Pressure

34. Metamorphic Grades

35. Metamorphic rock Protoliths (parent rocks) Parent rock Slate Phyllite Schist Gneiss Marble Quartzite Metamorphic rock Shale unknown Limestone Sandstone

36. Regional Metamorphism Contact Meta

37. Types of Metamorphism Contact Metamorphism occurs in rocks around a magma body high temperature (heat from magma) low pressure (occurs at shallow depths in the crust)

38. Contact Metamorphism

39. Metamorphic Grade

41. Low Grade Metamorphism Example: Slate forms at low temperature and pressure microscopic crystals dull luster clay and mica minerals foliated

42. Low Grade - Slate

43. Metamorphic Grade

44. Intermediate Grade Metamorphism Example: Phyllite intermediate temperature and pressure small crystals shiny luster mostly mica minerals foliated

45. Intermediate Grade – Phyllite

46. Metamorphic Grade

47. High Grade Metamorphism Example: Schist high temperature and pressure large crystals mica-rich foliated

48. High Grade - Schist Side view Top view

49. Metamorphic Grade

50. High Grade Metamorphism Example: Gneiss high temperature and pressure large crystals mica-poor foliated

51. High Grade - Gneiss

55. Regional Revisited Slate Phyllite Schist, Gneiss

56. Non-foliated Metamorphic Rocks granular texture interlocking grains composed primarily of one mineral uniform grain size

57. Nonfoliated - Marble metamorphosed limestone (CaCO 3 ) bedding and fossils obliterated

58. Nonfoliated - Quartzite metamorphosed quartz-rich sandstone Pore spaces filled with SiO 2