Brittle%20deformation

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Structural geology
Structure
Ductile deformation Fold Foliation Lineation
etc..
Brittle deformation Joint Tension
gash Styloite Fault etc..
Fault
Reconstruction of regional stress
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Fault surfaces displaying the direction of slip
lineation
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Stereographic projection of a fault slip data set
Slickenside lineation
Fault plane
Fault plane
Lower hemisphere project
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Method of right dihedrons
obtaining the orientation of principal stress
axes from statistic method
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STEREOGRAPHIC NET
S/S f (inclination)
S/S const.
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Wuff net
Schmidt net
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Wuff net (equiangular) OPM isosceles
triangle ON/OP tan (p/4-i/2) ON R tan
(p/4-i/2)
Schmidt net (equal-area) ON OX, OX (2)1/2
OH OH/OP sin (p/4-i/2) ON (2)1/2 R
sin (p/4-i/2)
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3D inversion of field data in fault tectonics
Eigenvalues and eigenvectors of T give the
orientation of principal stress axes (s1 , s2 and
s3), as well as the shape ratio F of the stress
ellipsoid (F (s2-s3)/(s1-s3)).
(e.g., Angelier, 1979, 1984, 1989, 1990)
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Inversion result
Field measured data
Computed stress axes
Theoretical fault shears
(Angelier, 1990)
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(Chang C. P., Unpubl.)
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Example from the seismic focal mechanism
F (s2-s3)/(s1-s3)
case 1
0 ? F ? 1
case 1
case 2

• ? 0
• reverse and strike-slip

case 2

• ? 1
• normal and strike-slip

(Kao and Jian, 2001)