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Today’s lecture

Today’s lecture. Application exercise Announcements Information about the research assignment Faults and stress. Announcements. No field trip on this Thursday, but yes on October 21! Note some schedule changes on the web site. Information about research assignment.

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Today’s lecture

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  1. GLG310 Structural Geology

  2. Today’s lecture • Application exercise • Announcements • Information about the research assignment • Faults and stress GLG310 Structural Geology

  3. Announcements • No field trip on this Thursday, but yes on October 21! • Note some schedule changes on the web site. GLG310 Structural Geology

  4. Information about research assignment • This assignment, due on December 2, will be 3-5 pages of double-spaced typed text (12 pt font like Times Roman). The assignment is to make some structural observations and measurements, or even a small geologic map, for any nearby geologic locality (of your choosing) and explain the geometry and deformation and interpret it in terms of geologic history and geologic processes. The paper must include at least 2 figures (they don't count towards the length) illustrating some aspect of your research. These figures can be anything (cartoon, sketch, simplified geologic cross-section, geologic map), but should be something you illustrate yourself. It should be neat, perhaps colored, but need not be drafted. You will also prepare and present (5 minutes) a poster, consisting of several figures, a summary, and bullet lists outlining key points about your research project. GLG310 Structural Geology

  5. Research assignment review • Two classmates must review your written paper before turning it in. Your should give them a typed, double-spaced draft of your paper and drafts of the figures and they will write corrections and suggestions on the draft, and then sign the bottom. You should incorporate their suggestions (at least those that are valid) into your final paper, and turn in the copies of your classmate's reviews along with your final paper. One of the best ways to write is edit someone else's writing. You will lose points if you do not get two meaningful reviews on a typed draft (not the final draft) of your paper--someone simply signing your final paper but making no comments or saying "Good job" is not a sufficient review! GLG310 Structural Geology

  6. Faults and stress: traction and stress Mohr Circle Graphical construction that lets us visualize the relationship between the principal stresses and tractions on a boundary (like a fault). • measured positive clockwise from s1 direction clockwise to plane of interest 2q measure positive clockwise from –sn direction on Mohr circle GLG310 Structural Geology

  7. Faults and stress: traction and stress Equations of the Mohr Circle (also “Cauchy’s equations”) GLG310 Structural Geology

  8. Faults and stress: traction and stress 90 GLG310 Structural Geology

  9. Faults and stress: traction and stress GLG310 Structural Geology

  10. Faults and stress: traction and stress GLG310 Structural Geology

  11. Faults and stress: traction and stress GLG310 Structural Geology

  12. Faults and stress: traction and stress 35 GLG310 Structural Geology

  13. Faults and stress: traction and stress -Davis and Reynolds t = ss GLG310 Structural Geology

  14. -Engelder, 1993, Stress regimes in the lithosphere, Princeton Univ. Press GLG310 Structural Geology

  15. Faults and stress: traction and stress Coulomb Law of Failure Coulomb equation tc = c + tan fsn Where tc = critical shear stress required for faulting (shear strength) c = cohesive strength tan f = coeffieicnet of internal friction = m GLG310 Structural Geology

  16. GLG310 Structural Geology

  17. Faults and stress: traction and stress GLG310 Structural Geology

  18. GLG310 Structural Geology -D+R

  19. GLG310 Structural Geology

  20. GLG310 Structural Geology

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