How rocks behave under different types of stress

How rocks behave under different types of stress (Earth Science)

1. How rocks behave under different types of stress

2. Objectives 2 Understand how rocks are deformed by stress and undergo solid deformation. Explain how tension, compression, and shear stresses produce geological structures.

3. Motivation But before our lesson, let’s play 3

4. SESTRS 4

5. STRESS 5

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7. STURC 7

8. CRUST 8

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10. STANIR 10

11. STRAIN 11

12. 12

13. TEALSIC 13

14. ELASTIC 14

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16. CORK 16

17. ROCK 17

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19. Body of the Report 19

20. Stress Vs. Strain

21. Strain When rocks deform they are said to  strain . A strain is a change in size, shape, or volume of a material. 21

22. Stress The forces acting on rock are called stress. Stress is the force applied on a rock per unit area. 22

23. Types of Stress

24. Types of Stress Tensional Stress Compressional Stress Shear Stress 24

25. Tensional Stress Tension stresses act in opposite directions, pulling rock apart or stretching it 25

26. 26 Tensional Stress

27. Compressional Stress Compression stresses act toward each other, pushing or squeezing rock together. 27

28. 28 Compressional Stress

29. Shear Stress Shear stresses may act toward or away from each other, but they do so along different lines of action, causing rock to twist or tear. 29

30. 30 Shear Stress

31. Stages of Deformation

32. Stages of Deformation Elastic Deformation Ductile Deformation Fracture 32

33. Elastic Deformation  wherein the strain is reversible. 33

34. Ductile Deformation wherein the strain is irreversible. 34

35. Fracture   irreversible strain wherein the material breaks . 35

36. Factors Affecting Deformation

37. FACTORS AFFECTING DEFORMATION Temperature Confining Pressure Strain Rate Composition 37

38. Temperature At high temperature molecules and their bonds can stretch and move, thus materials will behave in more ductile manner. At low Temperature, materials are brittle.  38

39. Confining Pressure  At high confining pressure materials are less likely to fracture because the pressure of the surroundings tends to hinder the formation of fractures. At low confining stress, material will be brittle and tend to fracture sooner.  39

40. Strain Rate At high strain rates material tends to fracture. At low strain rates more time is available for individual atoms to move and therefore ductile behavior is favored 40

41. Composition Some minerals are very brittle. This is due to the chemical bond types that hold them together. Thus, the mineralogical composition of the rock will be a factor in determining the deformational behavior of the rock. 41

42. Strike And Dip

43. Strike Strike is the compass direction of any horizontal line on the plane. 43

44. Dip The  dip  is the angle between a horizontal plane and the inclined plane, measured perpendicular to the direction of strike. 44

45. 45 Strike and Dip

46. ROCK BEHAVIORS

47. Rock Behaviors Brittle Ductile 47

48. Fracture of Brittle Rocks Joint Fault 48

49. Joint A  joint  is a fracture along which no movement has taken place, usually caused by tensional forces. 49

50. Fault  A  fault  is a fracture or break in the  rock along which movement has taken place 50

51. Types Of Faults

52. Types OF Faults Dip-Slip Fault Strike-Slip Fault Oblique-Sli p Fault 52

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56. Deformation of Ductile Rocks When rocks deform in a ductile manner, instead of fracturing to form faults or joints, they may bend or fold, and the resulting structures are called  folds. 56

57. Folds Folds result from compressional stresses or shear stresses acting over considerable time.  57

58. Kinds of Folds

59. Kinds of Folds Monoclines Anticlines Synclines 59

60. Monoclines Monoclines  are the simplest types of folds. Monoclines occur when horizontal strata are bent upward so that the two limbs of the fold are still horizontal. 60

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62. Anticlines Anticlines  are folds where the originally horizontal strata has been folded upward, and the two limbs of the fold dip away from the hinge of the fold. 62

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64. Synclines Synclines  are folds where the originally horizontal strata have been folded downward, and the two limbs of the fold dip inward toward the hinge of the fold.  64

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66. QUIZ 66

67. 67 QUIZ ENUMERATION 1-3 Types of Stress 4-6 Stages of Deformation 7-10 Factors Affecting Deformation 11-13 Types of Faults

68. 68 QUIZ 14. is the compass direction of any horizontal line on the plane . 15. The   is the angle between a horizontal plane and the inclined plane, measured perpendicular to the direction of strike.

69. ANSWERS 69

70. 70 ANSWERS Tensional Stress Compressional Stress Shear Stress Elastic Deformation Ductile Deformation Fracture Temperature Confining Pressure Strain Rate Composition Dip-Slip Fault Strike-Slip Fault Oblique-Slip Fault Strike Dip

71. 71 Thanks! ANY QUESTIONS ?

72. Presented by: Hessy Eya E. Culanag STEM 3 LOYAL 72