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Announcements

Announcements. Reminder: Application exercise on Tuesday, Sept. 17 in class How do videos look and work? Homework questions?. Strain and deformation. Stretch (strain) ellipse Rotation of lines in deformation Pure and simple shear Progressive deformation Deformation by change of volume.

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Announcements

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  1. GLG310 Structural Geology

  2. Announcements • Reminder: Application exercise on Tuesday, Sept. 17 in class • How do videos look and work? • Homework questions? GLG310 Structural Geology

  3. Strain and deformation • Stretch (strain) ellipse • Rotation of lines in deformation • Pure and simple shear • Progressive deformation • Deformation by change of volume GLG310 Structural Geology

  4. Moving from 1 to 2 to 3 dimensional deformation • E and s as we have defined them in the last two lectures are 1 dimensional (measured along lf). • In a deformed material; however, we can define the minimum and maximum stretches and they will be perpendicular Smin=lfmin/l0 l0 Smax=lfmax/l0 l0 lfmax lfmin GLG310 Structural Geology

  5. Principal stretches In 3D, S1 is max, S3 is min, and S2 is intermediate Sphere Ellipsoid Cube Prism GLG310 Structural Geology

  6. Deformed trilobites do exist! Draw the stretch ellipse for each GLG310 Structural Geology

  7. GLG310 Structural Geology

  8. GLG310 Structural Geology

  9. Angular shear

  10. GLG310 Structural Geology

  11. GLG310 Structural Geology

  12. “Coaxial deformation”: Lines parallel to principle axes do not rotate “Pure Shear”

  13. “Non-Coaxial deformation”: Principle axes are constant but lines rotate with progressive deformation “Simple Shear”

  14. Progressive deformation

  15. Cloos’ strain study

  16. Measured stretch ratios in rocks from around the world “Constriction” “Flattening” More common -Suppe, 1985 GLG310 Structural Geology

  17. Deformation by loss of material -dissolution -”styolites” http://www.earth.lsa.umich.edu/~vdpluijm/animations/stylolite.mov http://www.geol.umd.edu/~jmerck/geol100/images/15/stylolite.jpg

  18. Stylolite: Wave-like or tooth-like, serrated, interlocking surfaces most commonly seen in carbonate and quartz-rich rocks that contain concentrated insoluble residue such as clay minerals and iron oxides. Stylolites are thought to form by pressure solution, a dissolution process that reduces pore space under pressure during diagenesis. Schlumberger Oilfield Glossary http://www.glossary.oilfield.slb.com/Display.cfm?Term=stylolite GLG310 Structural Geology

  19. http://www.asaa.com.au/publications/magazines/DS16_DrDripstoneStylolites.pdfhttp://www.asaa.com.au/publications/magazines/DS16_DrDripstoneStylolites.pdf

  20. GLG310 Structural Geology

  21. Progressive strain History of regional deformation in southern Arizona GLG310 Structural Geology

  22. Stretching and Shortening working together in partnership -Pollard and Fletcher, Fundamentals of Structural Geology, 2005

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