1. Crustal Deformation

2. Crustal Deformation Types of Deformation Folds Faults & Joints
Subduction & Mountain Building
Collisional Mountain Belts

3. Terms
Dip angle
Angle of tilt away from horizontal

4. GEOL131: Crustal Deformation
Types of Deformation

5. Elastic Rock bends but snaps back to original shape Elastic limit
GEOL131: Crustal Deformation: Types of Deformation
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

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

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

8. GEOL131: Crustal Deformation
Folds

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

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

11. Anticlines & Synclines
GEOL131: Crustal Deformation: Folds
Anticlines & Synclines

12. GEOL131: Crustal Deformation: Folds
Domes

13. GEOL131: Crustal Deformation: Folds
Basins

14. GEOL131: Crustal Deformation: Folds
Monoclines

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

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

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

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

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

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

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

23. GEOL131: Crustal Deformation
Faults & Joints

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

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

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

27. Fault Block Mountains Tensional stress Normal faulting
GEOL131: Crustal Deformation: Faults & Joints
Fault Block Mountains
Tensional stress
Normal faulting

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

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

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

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

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

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

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

35. GEOL131: Crustal Deformation
Mountain Building

36. Types of Mountain Building
Fault-block
Andean
Collisional
Cordilleran
Alpine

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

38. Andean-Type Mountain Building
GEOL131: Crustal Deformation: Subduction & Mountain Building
Andean-Type Mountain Building
First stage
Development of continental volcanic arc
Emplacement of igneous plutons
Development of accretionary wedge

39. Andean-Type Mountain Building
GEOL131: Crustal Deformation: Subduction & Mountain Building
Andean-Type Mountain Building
Second stage
Subduction stops
Uplift and erosion of igneous plutons
Uplift of accretionary wedge

40. Collisional Mountain Belts
GEOL131: Crustal Deformation
Collisional Mountain Belts

41. Cordilleran-Type Mountain Building
GEOL131: Crustal Deformation: Collisional Mountain Belts
Cordilleran-Type Mountain Building
Accretion of multiple volcanic island arcs onto a continent

42. Alpine-Type Mountain Building
GEOL131: Crustal Deformation: Collisional Mountain Belts
Alpine-Type Mountain Building
Collision of two continents

43. Alpine-Type Mountain Building
GEOL131: Crustal Deformation: Collisional Mountain Belts
Alpine-Type Mountain Building
Continental escape: blocks of continental crust are pushed away from a continental collision zone

44. End of Chapter