Geology 3120 Introduction to StrikeSlip Faults

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Geology 3120 - Introduction to Strike-Slip Faults
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Levant Strike-Slip Faults
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(No Transcript)
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Outline

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

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Stick-Slip Elastic Rebound Theory
D
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Elastic Rebound Theory

• Imagine a fence across an active fault

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Elastic Rebound Theory

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

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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

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Elastic Rebound Theory
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Elastic Rebound Theory
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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)

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Andersonian Theory
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Conjugate Strike-Slip Faults
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Determining Sense of Slip
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Right-Lateral (Dextral)
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Left-Lateral (Sinistral)
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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
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Arrow Heads ( ) and Tails ( )

• Right-lateral or left-lateral?

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Arrow Heads ( ) and Tails ( )

• Left-lateral

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Arrow Heads ( ) and Tails ( )

• Sinistral or Dextral?

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Arrow Heads ( ) and Tails ( )

• Dextral

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Strike-Slip Faulting Shallow Brittle vs Deep
Shear
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Strike-Slip Faulting EQs dislocations
See http//www.data.scec.org/Module/links/landrupt
.html Landers rupture propagation movies
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Strike-Slip Faults on Continental Margins
50 m
N

• What is the sense of slip?

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Strike-Slip Faults on Continental Margins
50 m
N

• Right-lateral (dextral)

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Transtension
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Development of a Pull-Apart Basin
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Pull-Apart Basin
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Initial Releasing Bend
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Evolution of a Releasing Bend
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Normal (-) Flower Structure - Tulip
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Transpression
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Development of a Restraining Bend
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Initial Restraining Bend
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Evolution of a Restraining Bend
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Reverse () Flower Structure - Palm
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Summary of Flower Structures - Palms Tulips
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Oceanic Strike Slip fault Transforms
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Strike-Slip Faults on Mid-Ocean Ridges

• What is the sense of slip?

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Strike-Slip Faults on Mid-Ocean Ridges

• Right-lateral (Dextral)

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Pacific-Antarctic Ridge

• Magnetic anomalies from present to 9.9 Ma
• Warm colors indicate positive polarity
• Cool colors indicate reverse polarity