Lecture 1- Microstructures and Deformation Mechanisms

VIEPS/Mainz Microstructure Course  
| TOC | Lecture 1 2 3 4 a b 5 a b | Lab 1 a b c 2 a b c 3 a b 4 a b 5 a b | Glossary Table 1 2 3 4 5 Index |

1) Introduction

2) Why do we study microstructures?
Fig 01

3) How do we study microstructures

4) Deformation Mechanisms & Processes

a) Definitions: Deformation Mechanisms are processes that lead to a change in shape of rock

There are many other processes, often deformation related, that don't lead to change in shape

b) Defectsimperfections in the structure of a crystal, and can be 0-dimensional, 1-dimensional or 2-dimensional

c) Movement of Point Defects: Coble creep & Nabarro-Herring creep:
Fig 06

The images below are of detrital quartz grains in a calcite shear zone. they are single crystals with no evidence of rotation recrystallisation in wings. The lace network on surface reflects cte-cte-qtz triple junctions. They probably formed as a result of Coble and/or Nabarro-Herring creep. Images courtesy of Michel Bestmann (michel@geol.uni-erlangen.de Institut für Geologie und Mineralogie, Schloßgarten 5, 91054 Erlangen, Germany)

d) Direct Observation of dislocations:

e) Movement of dislocations:

Dislocation glide (edge dislocation)

f) Rheology of dislocation glide:

Fig 03
Fig 04
Fig 05



h) Kinking

h) Grain boundary sliding

i) Other deformation processes:

j) Deformation mechanism maps