1. Crustal Deformation

2. Types of Deformation Folds Faults & Joints

3. Terms Dip angle –Angle of tilt away from horizontal

4. Types of Deformation GEOL131: Crustal Deformation

5. Elastic Rock bends but snaps back to original shape –Earthquakes Elastic limit –Capacity of rock for elastic deformation If elastic limit exceeded, deformation is permanent GEOL131: Crustal Deformation: Types of Deformation

6. Brittle Rock breaks Colder, harder, and shallower rock tends to be brittle GEOL131: Crustal Deformation: Types of Deformation

7. Ductile Rock bends permanently Deeper, hotter, weaker rock tends to be ductile GEOL131: Crustal Deformation: Types of Deformation

8. Folds GEOL131: Crustal Deformation

9. Folded Rocks Product of ductile deformation Form at deep crustal levels –Rock is warmer GEOL131: Crustal Deformation

10. Basic Fold Anatomy GEOL131: Crustal Deformation: Folds Axis Limb

11. Anticlines & Synclines GEOL131: Crustal Deformation: Folds

12. Domes GEOL131: Crustal Deformation: Folds

13. Basins GEOL131: Crustal Deformation: Folds

14. Monoclines GEOL131: Crustal Deformation: Folds

15. Fold Orientations GEOL131: Crustal Deformation: Folds Symmetrical –Both limbs have same dip angle Asymmetrical –Limbs have different dip angles

16. Fold Orientations GEOL131: Crustal Deformation: Folds Overturned –One limb tilted more than 90 degrees Recumbent –Both limbs horizontal

17. Fold Orientations GEOL131: Crustal Deformation: Folds Upright –Fold axis not tilted Plunging –Fold axis is tilted

18. Recognizing folds in map view GEOL131: Crustal Deformation: Folds What patterns do folds make on the Earth’s surface? There is usually no cross-section view available to geologists

19. Recognizing folds in map view GEOL131: Crustal Deformation: Folds Upright anticline Upright syncline Oldest layer Youngest layer

20. Recognizing folds in map view GEOL131: Crustal Deformation: Folds Upright anticline Upright syncline Oldest layer at center Youngest layer at center

21. Recognizing folds in map view GEOL131: Crustal Deformation: Folds Arrows show direction of fold axis tilt Oldest layer at center Youngest layer at center

22. Recognizing folds in map view GEOL131: Crustal Deformation: Folds Dome: oldest layer at center Basin: youngest layer at center

23. Faults & Joints GEOL131: Crustal Deformation

24. Basic Fault Anatomy GEOL131: Crustal Deformation: Faults & Joints Hanging Wall Footwall

25. Normal faults Reverse faults Thrust faults Dip-Slip Faults GEOL131: Crustal Deformation: Faults & Joints

26. Dip-Slip Faults: Normal GEOL131: Crustal Deformation: Faults & Joints

27. Dip-Slip Faults: Reverse GEOL131: Crustal Deformation: Faults & Joints

28. Dip-Slip Faults: Thrust GEOL131: Crustal Deformation: Faults & Joints

29. Normal faults –Tensional stress –Hanging wall moves down Reverse faults –Compressional stress –Hanging wall moves up Thrust faults –Compressional stress –Footwall moves up –Lower angle than reverse faults Dip-Slip Faults: Summary GEOL131: Crustal Deformation: Faults & Joints

30. Left-lateral Right-lateral Caused by shear stress Strike-Slip Faults GEOL131: Crustal Deformation: Faults & Joints

31. Strike-Slip Faults GEOL131: Crustal Deformation: Faults & Joints (Right-lateral)

32. Joints Fractures with no movement Cause accelerated weathering GEOL131: Crustal Deformation: Faults & Joints Weathered joints in southern Utah

33. Mountain Building GEOL131: Crustal Deformation

34. Types of Tectonic Mountain Building Subduction zone Continental collision Fault-block mountains GEOL131: Crustal Deformation: Mountain Building

35. New Term GEOL131: Crustal Deformation: Mountain Building ACCRETIONARY WEDGE: Sediment & rock scraped off subducting plate onto overriding plate

36. Mountains Built at Subduction Zones Volcanic arc Uplifted accretionary wedge Uplifted igneous intrusions Accreted volcanic island arc GEOL131: Crustal Deformation: Mountain Building

37. Mountains Built at Subduction Zones: Volcanic arc GEOL131: Crustal Deformation: Mountain Building

38. Mountains Built at Subduction Zones: Uplifted accretionary wedge GEOL131: Crustal Deformation: Mountain Building

39. Mountains Built at Subduction Zones: Uplifted accretionary wedge GEOL131: Crustal Deformation: Mountain Building

40. Mountains Built at Subduction Zones: Uplifted igneous intrusions GEOL131: Crustal Deformation: Mountain Building

41. Mountains Built at Subduction Zones: Accreted Volcanic Island Arc GEOL131: Crustal Deformation: Mountain Building

42. Mountains Built by Continental Collisions GEOL131: Crustal Deformation: Mountain Building

43. Mountains Built by Continental Collisions GEOL131: Crustal Deformation: Mountain Building Continental escape: blocks of continental crust are pushed away from a continental collision zone

44. Mountains Built by Continental Collisions Compressional stress Folding Reverse and thrust faulting GEOL131: Crustal Deformation: Mountain Building

45. Fault Block Mountains Tensional stress Normal faulting GEOL131: Crustal Deformation: Mountain Building

46. Fault Block Mountains GEOL131: Crustal Deformation: Mountain Building Grand Tetons

47. End of Chapter