Structural Geology: Lecture 14

1
Structural Geology Lecture 14

• Review of last lecture (strike-slip fault
  systems structures along straight and curved
  master strands).
• Termination mechanisms of strike-slip faults
  (extensional, contractional, and diffuse).
• Stress (1-D conceptual demonstration 2-D case as
  represented by Mohr circle 3-D by stress
  tensor).

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Termination structures of strike-slip faults
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Termination mechanisms of strike-slip
faults Thrusts or normal faults
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Diffuse termination of strike-slip faults
Horsetail structures
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• Stress
• What is stress?
• How does differ from force?

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• Surface and body force
• Internal and external force
• Traction and stress

Qualitatively, stress is surface and also
internal force, but its rigorous definition can
only be expressed in a tensor form.
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• Concept of stress in 1-D normal and shear stress
  components.
• Concept of stress in 2-D Mohr circle.
• Concept of stress in 3-D tensor form of stress
  and stress notation
• Principal stress and principal stress directions.
• Mean stress and pressure
• Deviatoric stress
• Maximum shear stress
• Differential stress.
• Hydrostatic and lithostatic pressure/stress

8

• Coulomb fracture criterion (critical shear
  stress, internal coefficient of friction, and
  cohesion).
• Frictional law (coefficient of friction).
• Pore-fluid pressure and effective stress.