1. Ductile Deformation Processes Chapter 9 in Van der Pluijm and Marshak

2. How can solid rock flow like taffy? Swiss Alps

3. Ice is a solid phase that flows when conditions are appropriate and there are forces acting on the material. “g”

4. Ductile deformation is permanent

5. Accomplished by these 3 mechanisms: Cataclastic flow Diffusional mass transfer Crystal plasticity

6. Mechanism is determined by: Temperature Stress Strain rate Grain size Composition Fluid content

7. Effect of Composition Slow Halite Gypsum Calcite Quartz Plag. Pyroxene Olivine

8. 1) Cataclastic flow: small pieces sliding past each other

9. Cataclastic flow: Is it brittle or ductile? Ductile on large scale but brittle on small scale

10. 2) Crystal Plasticity: The crystal changes shape by movement of lattice defects Point Defects are vacancies or impurities

12. Dislocations form in 2 ways: During crystal growth During deformation

13. By moving the dislocations, the crystal changes shape

15. Migrating defects change the lattice shape. Occurs under stress

16. Line defects in olivine

17. Twinning also changes the crystal shape

18. 3) Diffusional Mass Transfer has three mechanisms: Grain boundary diffusion Volume diffusion Pressure solutionLow T High T

19. Grain boundary diffusion Atoms will diffuse along the edges of the grain to create shape changes (strain).

20. Volume diffusion Atoms will diffuse through the center of the grain to create shape changes (strain).

21. Pressure solution: Material is dissolved under stress Dissolved rock goes into veins

22. Deformed Marble

23. Mylonite