Abstract

Rock deformation is heterogeneous at all spatial and temporal scales. This heterogeneity results in the formation of structures like faults and folds and is therefore of particular interest to geologists. Quantitative description of how rock deforms heterogeneously is fundamental to improving our understanding of the processes underlying this complicated behavior. Previous studies of deformation that vary in space and time have been qualitative. In the first two chapters of this dissertation, I present the theory necessary to quantitatively study deformation that varies in space and time. In the second two chapters, I apply the theory to the study of naturally deformed rocks and provide examples of the wide variety of information about deformation processes that can be extracted from rocks.

In the first chapter I present a methodology to quantify spatial deformation variation. I show how the bulk amount of deformation recorded by a heterogeneously rock is preserved in the various components of the rock. This method provides a way to quantitatively study the relative contributions of a rock's components to bulk deformation. In the second chapter I present a methodology to quantify temporal deformation variation. This methodology allows determination of constraints on a body of rock's possible deformation histories. In the third chapter, I demonstrate how useful kinematic information about magmatic flow can be extracted from phenocryst fabric data in igneous intrusions. I show that fabric in igneous intrusions preserves only part of the magma's kinematic history. Interpretations of magma flow based on phenocryst fabric must therefore be approached with caution. In the final chapter I present and discuss the results of a detailed examination of heterogeneous rock deformation at several scales in the east-central Sierra Nevada of California, U.S.A. At the centimeter, meter, and kilometer scales of observation, various kinds of rock record different amounts of deformation. Inferences of variation in rock viscosity at each scale, however, suggest that the range of rock viscosities is limited to an order of magnitude or less.