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Geology 3120 - Introduction to Strike-Slip Faults

Geology 3120 - Introduction to Strike-Slip Faults. Levant Strike-Slip Faults. Outline. Stick-Slip and Creep Andersonian Theory Kinematics Strike-Slip Faults on Continental Margins Strike-Slip Faults on Mid-Ocean Ridges. Stick-Slip: Elastic Rebound Theory. D. Elastic Rebound Theory.

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Geology 3120 - Introduction to Strike-Slip Faults

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  1. Geology 3120 - Introduction to Strike-Slip Faults

  2. Levant Strike-Slip Faults

  3. Outline • Stick-Slip and Creep • Andersonian Theory • Kinematics • Strike-Slip Faults on Continental Margins • Strike-Slip Faults on Mid-Ocean Ridges

  4. Stick-Slip: Elastic Rebound Theory D

  5. Elastic Rebound Theory • Imagine a fence across an active fault

  6. Elastic Rebound Theory • Imagine a fence across an active fault • Regional deformation occurs but the fault does not break. The fence becomes curved.

  7. Elastic Rebound Theory • Imagine a fence across an active fault • Regional deformation occurs but the fault does not break. • Once the fault breaks, the fence is sheared in half and marks offset • Note that far-field strain may limit whether the fault accommodates all the plate motion at its trace

  8. Elastic Rebound Theory

  9. Elastic Rebound Theory

  10. Creep (Aseismic Slip) • Imagine a fence across an active fault • Slip occurs slowly on the fault continually over time. • Creeping faults do not store elastic energy that might be released by a stick-slip event (an earthquake)

  11. Andersonian Theory

  12. Conjugate Strike-Slip Faults

  13. Determining Sense of Slip

  14. Right-Lateral (Dextral)

  15. Left-Lateral (Sinistral)

  16. Arrow Heads ( ) and Tails ( ) Block moving toward you like an arrowhead heading towards you Block moving away from you like seeing the feathers of an arrow

  17. Arrow Heads ( ) and Tails ( ) Right-lateral or left-lateral?

  18. Arrow Heads ( ) and Tails ( ) Left-lateral

  19. Arrow Heads ( ) and Tails ( ) Sinistral or Dextral?

  20. Arrow Heads ( ) and Tails ( ) Dextral

  21. Strike-Slip Faulting: Shallow Brittle vs Deep Shear

  22. Strike-Slip Faulting: EQ’s = dislocations See http://www.data.scec.org/Module/links/landrupt.html Landers rupture propagation movies

  23. Strike-Slip Faults on Continental Margins 50 m N What is the sense of slip?

  24. Strike-Slip Faults on Continental Margins 50 m N Right-lateral (dextral)

  25. Transtension

  26. Development of a Pull-Apart Basin

  27. Pull-Apart Basin

  28. Initial Releasing Bend

  29. Evolution of a Releasing Bend

  30. Normal (-) Flower Structure - Tulip

  31. Transpression

  32. Development of a Restraining Bend

  33. Initial Restraining Bend

  34. Evolution of a Restraining Bend

  35. Reverse (+) Flower Structure - Palm

  36. Summary of Flower Structures - Palms & Tulips

  37. Oceanic Strike Slip fault: Transforms

  38. Strike-Slip Faults on Mid-Ocean Ridges What is the sense of slip?

  39. Strike-Slip Faults on Mid-Ocean Ridges Right-lateral (Dextral)

  40. Pacific-Antarctic Ridge Magnetic anomalies from present to 9.9 Ma Warm colors indicate positive polarity Cool colors indicate reverse polarity

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