Chapter 9 PM - Geology 3443 Spring 2006 Chapter 9 Ductile Deformation Mechanisms Introduction 1 What are the three mechanisms considered in this

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Geology 3443 Spring 2006 Chapter 9 – Ductile Deformation Mechanisms Introduction 1. What are the three mechanisms considered in this chapter? Crystal plasticity, diffusional mass transfer, cataclastic flow. Why is cataclastic flow considered ductile behavior rather then brittle? Because it is distributed throughout the rock on a microscopic scale 2. What are the primary parameters that control which ductile mechanism operates in a rock? Temperature, stress, strain rate, grain size, composition, fluid content 3. What is homologous temperature? The absolute temperature divided by the absolute melting temperature oft the rock. Why is it a better measurement for ductile mechanisms that normal temperature? Because different minerals have different temperatures where they display ductile behavior Cataclastic Flow 4. Describe what happens to grains and minerals during cataclastic flow.- bonds break at microscopic scale and begin to slid past on each other but keep there overall shape. If cataclastic flow occurs along a narrow zone, is it considered ductile? Yes. Why?- because it is a process that deforms at a small scale and leaves rocks away from fracture unaffected Crystal Defects 5. What are point defects and how are they produced?- Point defects occur in all natural minerals and consist of vacancies, the wrong atom or radical at a particular lattice position, and atoms contained between lattice sites. All of these defects distort the electrostatic forces and bonds creating weak points . 6. What are line defects and how are they produced?- dislocations: 1) edge dislocation occur when an upper lattice slips over a lower lattice and 2) screw dislocation- occur when one part of the lattice slips over an adjacent part. However, the slip direction is parallel to the edge producing a twisting effect on the lattice. They are distinguished by whether the slip (Burgers vector) is perpendicular to the dislocation edge or parallel to the edge 7. How are edge dislocations different from screw dislocations?- . They are distinguished by whether the slip (Burgers vector) is perpendicular to the dislocation edge or parallel to the edge. How is a burgers vector determined? Arrows connecting two ends of an
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This note was uploaded on 01/03/2011 for the course GEOL 3443 taught by Professor Staff during the Fall '08 term at UT Arlington.

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Chapter 9 PM - Geology 3443 Spring 2006 Chapter 9 Ductile Deformation Mechanisms Introduction 1 What are the three mechanisms considered in this

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