glg310 structural geology. 21 december 2015glg310 structural geology
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GLG310 Structural Geology
April 21, 2023 GLG310 Structural Geology
GLG310 Structural Geology
d is differential stress
-Engelder, 1993, Stress regimes in the lithosphere, Princeton Univ. Press
April 21, 2023 GLG510 Advanced Structural Geology
Rheology: “science of deformation and flow
of matter”or
relationship between stress and strain
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
GLG310 Structural Geology
April 21, 2023 GLG510 Advanced Structural Geology
E (young’s modulus) = d a/d ea Units of stress
-Pollard and Fletcher, 2005
April 21, 2023 GLG310 Structural Geology
http://silver.neep.wisc.edu/~lakes/PoissonIntro.html
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
Idealized Elastic Material
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)
http://www.see.leeds.ac.uk/structure/rheology/inelastic.htm
Plasticity• Steady deformation at yield strength
Plasticity• Steady deformation at yield strength
April 21, 2023 GLG510 Advanced Structural Geology
Viscosity• Strain rate proportional to differential stress
April 21, 2023 GLG310 Structural Geology
April 21, 2023 GLG310 Structural Geology
http://www.youtube.com/watch?v=GxdfoJoWNE4
Variations in mechanical behavior
April 21, 2023 GLG310 Structural Geology
Rock deformation experiments
April 21, 2023 GLG310 Structural Geology
GLG310 Structural Geology
http://www.cast.com.sg/s_soil.html
April 21, 2023 GLG310 Structural Geology
http://www.youtube.com/watch?v=n4ZAb-p-dIw
http://maydamedia.com/Images/Chapter11/Chart11.1.jpg
Rocks can flow: salt ascends through overlying sediments because it is bouyant
April 21, 2023 GLG310 Structural Geology