Overvoltage Research and Geophysical Applications deals with the subject of overvoltage (or induced electrical polarization) as it relates to geophysical exploration. This book presents the results of theoretical and experimental research conducted between 1946 and 1958 to investigate overvoltage and sponsored by Newmont Mining Corporation. This book is comprised of 10 chapters and begins with a brief overview of the history of Newmont's interest in overvoltage. The next chapter describes a theory for induced polarization effects (for step-function excitation), with particular reference to a mathematical formulation that represents the volume distribution of dipolar sources. The reader is then introduced to a brief theoretical derivation for the effective conductivity and dielectric constant of a homogeneous medium loaded with a uniform distribution of spherical conducting particles. The following chapters explore the complex conductivity of rocks as a function of frequency; laboratory studies of induced polarization in mineralized and non-mineralized rock specimens; induced polarization decay curves on rock specimens; and phenomena resulting from electric polarization of rocks at low frequencies. Some electrical transient measurements on igneous, sedimentary, and metamorphic rocks are presented. The final chapter considers various explanations of the normal effect and describes induced-polarization experiments. This monograph will be of interest to geophysicists.
Table of Contents
Preface Chapter 1 Historical Summary of Overvoltage Developments by Newmont Exploration Limited, 1946-1955 Chapter 2 A Theory for Induced Polarization Effects (for Step-Function Excitation) Chapter 3 A Phenomenological Theory of Overvoltage for Metallic Particles Chapter 4 The Variable-Frequency Method Chapter 5 Laboratory Investigation of Overvoltage Chapter 6A Criteria from the Transient Decay Curves Chapter 6B Analysis of the Frequency Response Data Chapter 7 Analysis of Some Electrical Transient Measurements on Igneous, Sedimentary and Metamorphic Rocks Chapter 8 Field Equipment for Prospecting by the Overvoltage Method Chapter 9 Overvoltage Field Results Chapter 10A The Normal Effect—Part I Chapter 10B The Normal Effect—Part II