Page 22 - Microtectonics
P. 22
2
Flow and Deformation
2.1 n this chapter, basic principles of continuum mechanics are explained in a non-
Introduction Imathematical way, assuming no previous knowledge of the subject and using
simple concepts and illustrations. Continuum mechanics is a subject that is con-
2.2 sidered to be difficult by many students, and seen as too theoretical to be of
Terminology practical use in the interpretation of geological structures. It is true that it is rarely
possible to make detailed reconstructions of flow and flow history for a rock sam-
2.3 ple, but it is crucial to have a basic understanding of the mathematical tools to
Description and describe the motion of particles in a continuum, and the interaction of forces
Reconstruction of and motion in a volume of rock. In this book, there is no space to give a detailed
Deformation treatment of the subject, but we aim to treat at least the basic terminology so
that the reader can work through the literature on microstructures unaided.
2.4 In the first part of the chapter, reference frames are explained as a necessary
Reference Frames tool to describe flow and deformation, and it is important to realize how a choice
of reference frame can influence the description of deformation patterns. Then,
2.5 flow, and deformation are treated including the important concepts of instanta-
Homogeneous and neous stretching axes, vorticity, and the kinematic vorticity number. The central
Inhomogeneous Flow part of this chapter explains kinematics and how to understand the motion of
and Deformation particles in a rock in two and three dimensions. Finally, the concepts of stress and
rheology are briefly explained, and basic terminology of these subjects given.
2.6
Deformation and Strain
2.7
Progressive and Finite
Deformation
2.8
Flow and Deformation
in Three Dimensions
2.9
Fabric Attractor
2.10
Application to Rocks
2.11
Stress and Deformation
2.12
Rheology