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GLG310 Structural Geology

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Page 1: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

GLG310 Structural Geology

Page 2: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

Page 3: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

GLG310 Structural Geology

d is differential stress

-Engelder, 1993, Stress regimes in the lithosphere, Princeton Univ. Press

Page 4: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG510 Advanced Structural Geology

Rheology: “science of deformation and flow

of matter”or

relationship between stress and strain

Page 5: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

Idealized Elastic MaterialLinear relationship between force and extension (Hooke, 1676):

•Ut tensio sic uis

•As extension so the force

•Analogous to spring constant

http://www.see.leeds.ac.uk/structure/rheology/hooke.htm

Page 6: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

GLG310 Structural Geology

Page 7: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG510 Advanced Structural Geology

E (young’s modulus) = d a/d ea Units of stress

-Pollard and Fletcher, 2005

Page 8: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

http://silver.neep.wisc.edu/~lakes/PoissonIntro.html

Page 9: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG510 Advanced Structural Geology

a = f/A ea = (b-B)/B

p = 0 ep = (w-W)/W

= - ep / ea

(Poisson ratio)Measures compressibility

Axial versus transverse

deformation

Page 10: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

Idealized Elastic Material

Page 11: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG510 Advanced Structural Geology

Stiffness and strength“Lest there be any possible, probably, shadow of doubt,

strength is not, repeat not, the same thing as stiffness. Stiffness, or Young’s modulus or E, is concerned with how stiff, flexible, springy or floppy a material is. Strength is the force or stress needed to break a thing. A biscuit is stiff but weak, steel is stiff and strong, nylon is flexible (low E and strong), raspberry jelly is flexible (low E) and weak. The two properties together describe a solid about as well as you can reasonably expect two figures to do.”

(Gordon, New science of strong materials, 2006)

Page 12: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

http://www.see.leeds.ac.uk/structure/rheology/inelastic.htm

Page 13: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

Plasticity• Steady deformation at yield strength

Page 14: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

Plasticity• Steady deformation at yield strength

Page 15: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG510 Advanced Structural Geology

Viscosity• Strain rate proportional to differential stress

Page 16: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

Page 17: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

http://www.youtube.com/watch?v=GxdfoJoWNE4

Variations in mechanical behavior

Page 18: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

Rock deformation experiments

Page 19: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

Page 20: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

GLG310 Structural Geology

Page 21: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology
Page 22: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

http://www.cast.com.sg/s_soil.html

Page 23: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology
Page 24: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology

http://www.youtube.com/watch?v=n4ZAb-p-dIw

Page 25: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

http://maydamedia.com/Images/Chapter11/Chart11.1.jpg

Rocks can flow: salt ascends through overlying sediments because it is bouyant

Page 26: GLG310 Structural Geology. 21 December 2015GLG310 Structural Geology

April 21, 2023 GLG310 Structural Geology