Overvoltage Research and Geophysical Applications

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.

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