Geology 3120 Introduction to Thrust Faults

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Geology 3120 - Introduction to Thrust Faults
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Outline

• Terminology
• Calculating stretch and shortening
• Throw, heave, and slip
• Stratigraphy and thrust faults

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Thrust Fault
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Thrust Fault Terminology
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Thrust Fault Terminology
Fault achieves trajectory rapidly
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Fault Bend Fold Movie
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Thrust Fault Terminology
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Calculating Shortening for Thrust Faults
( )
lf
-1 100
shortening
If Stretch S lf/lo, then
lo
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Calculating Shortening for Thrust Faults
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A Caution Regarding Shortening
Choosing a minimum lo value yields maximum
shortening
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Shortening Calculation

• Thus shortening is relative to the baseline you
  pick

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Throw, Heave, and Slip
Q
Heave
Q
Throw
Slip
Q
(Throw)2 (Heave)2 (Slip)2 SinQ
(Throw/Slip) CosQ (Heave/Slip)
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Increasing Stratigraphic Thickness
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Evidence for Thrust Faulting in Boreholes
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Evidence for Thrust Faulting in Boreholes
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Evidence for Thrust Faulting in Boreholes
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References
Slides 3-9 http//earth.leeds.ac.uk/faults/thrust/
rampflat/index.htm Slides 10-14 Twiss, R. J. and
E. M. Moores, Structural Geology, W. H. Freeman
Co., New York, 532 p., 1992.