Strain Fabrics

Abstract

Throughout this book, we are concerned with the quantitative description of microstructures, mainly because we believe that microstructures reveal aspects of the physical properties or the physical processes that occur or have occurred in the rock material. In the previous (chapters 14 and 15), we have paid particular attention to the particle and the surface fabric (P- and S-fabric) deriving preferred orientations or alignment of particles and grains or grain boundary surfaces and determining degrees of anisotropy. In this chapter we will discuss how P- and S-fabrics can be used to derive the state of (finite) strain in a sample. Maybe even more importantly, we will learn how to test whether a given anisotropic microstructure can be produced by strain at all or if some other (non-straining) process has to be invoked. At the end of the chapter we will compare the SURFOR method with the classical method for strain analysis, the R_f–ϕ method by Ramsay (1967).