PAGEOPH, gol. 146, No. I ( 1 9 9 6 ) 0033-4553/96/010195-1151.50 + 0.20/0 �9 1996 Birkh/iuser Verlag, Basel

Book Review

Geochemical Self-organizath)n by Peter J. Ortoleva, (Oxford Monographs on Geol- ogy and Geophysics No. 23), Oxford University Press, 1994; US $89.95.

Every geoscientist confronts difficult geology with a mixture of training, obser- vation and interpretation. This book provides an exciting approach to the under- standing of many geochemical phenomena, in that it challenges many commonly held beliefs concerning our knowledge and application of equilibrium thermody- namics in geochemical processes. Indeed Ortoleva presents the first comprehensive attempt to quantify a broad range of disequilibrium processes in geochemistry.

Geochemical self-organization provides a framework for understanding chemi- cal zoning patterns at a range of scales. The premise of self-organization is that not all observed zonations are externally imposed (e.g., by broad thermal, chemical, or stress gradients), some being derived by internal coupling of reaction and mass transport. Organized systems can be developed, without disobeying the second law of thermodynamics, if an increase of order occurs at one scale, at the expense of an overall decrease in order at a broader scale. Most of us are familiar with several types of disequilibrium processes, even if we have traditionally attempted to treat them in terms of local equilibrium. Well-known examples include convection (discussed in Ortoleva's introduction as a classic example of self-organization) and reaction fronts. The development of gneissosity in high-grade metamorphic rocks is another good example, in which the effect of relatively low surface energy across boundaries between similar mineral grains drives the segregation process. The internal factors which are operating (grain boundary surface energies) may be treated separately from the external factors (e.g., far-field stresses), using the approach presented by Ortoleva. Many other types of repeated banding patterns are discussed and modeled in this book, including for example, Liesegang banding, on which much of the earlier literature on self-organization was focussed.

Despite the author's modest statement that he did not intend that the book would be "complete," it is certainly well organized (although presumably not due to self-organization). The first two chapters are introductory, dealing with the general and mathematical basis behind self-organization. These are followed by a chapter treating oscillatory zoning in crystals. Then comes a general chapter on reaction-transport modeling which serves to introduce five subsequent chapters regarding reaction fronts, including Liesegang banding. Another general one on mechanochemical coupling follows, introducing a series of fascinating chapters in the latter part of the book which present some intriguing alternatives to patterning

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at a range of scales. Metamorphic and diagenetic differentiation patterns are covered, as is a range of concretionary/concentric patterns (including orbicular granites) and reaction-driven advection phenomena (mainly concerned with convec- tion and pressure solution). The last two chapters are conceptually challenging, to say the least! These deal with compartmentalization of sedimentary basins by self-organization, and the application of self-organization theories to regional scale patterns of fracture, sealing, methanogenesis, and simulation of flow in fractured, porous media.

Each of the chapters dealing with specific examples of self-organization follows a pattern of general introduction, mathematical theory, and worked models. A full appreciation of the concepts behind self-organization presented in this book re- quires a good working knowledge of pure mathematics. A sound understanding of geochemistry and kinetics is also desirable. However, because the book is lucidly written, it is possible to appreciate the main thrust of any argument presented without getting bogged down in the theory. This is facilitated by many diagrams simply and clearly displayed throughout the body of the text, although unfortu- nately there are far fewer field or petrographic photographs to complement these, one of the few criticisms that can be raised about this otherwise very well presented book.

To the author's credit, the book is not written in an intimidatory or dismissive style with respect to equilibrium geochemistry or other conventionally accepted ideas about patterned features. Rather, he presents conventional concepts at the start of each chapter, followed by his concepts of self-organization. He then proceeds to either integrate the two sets of concepts or subtly present alternative models without being entirely dismissive of the conventional ones. His chapter on oscillatory zoning in crystals is an excellent example, whereby he presents the general model for oscilliation caused by a corresponding oscilliation in magma composition, followed by a self-organization model which does not p e r se require magmatic compositional variation, but can operate in tandem with it.

Although the book is clearly not intended for the average undergraduate student, there are many concepts presented that should eventually find their way into undergraduate and postgraduate curricula as geochemists realize the impor- tance of these processes. It is most suitable for postgraduate students and re- searchers studying the fields of diagenetic, hydrothermal and metamorphic fluid flow; magmatic differentiation; sedimentary petrology, and sedimentary basin archi- tecture. It will also strongly appeal to any geoscientist who, at one point in time, has stood in front of some Liesegang bands or an orbicular granite, and thought to themselves, "What exactly is going on here?" (or a similar phrase). If these or similar patterns have intrigued you in the past, this book will open your eyes.

My reasons for offering to review the book lie partly in confusion over interpretation of some unusual patterns of asymmetric reaction zones and veins that have been troubling a colleague and me for years. We have gathered a thorough

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and comprehensive geochemical, stable isotopic and petrological data set, to no avail until now. This book offers us a considerably broader view towards under-

standing these phenomena, and we are confident of solving our problem in the near future. If you are struck by a similar geochemical problem, or wish to broaden your philosophy and conceptual base of geochemistry, I thoroughly recommend this book.

Nick Oliver School of Applied Geology Curtin University GPO Box U1987 Perth, 6001 Western Australia.

Flow and Contaminant Transport in Fractured Rock, edited by Jacob Bear, Chin-Fu Tsang, and Ghislain de Marsily, Academic Press, 1993; US $99.00.

The study of fractured rock systems is the great "second wave" of hydrogeol- ogy, a science that is quickly moving beyond the "first wave," porous medium hydrology. (Ten or twenty years from now, I hope we will be reading reviews of current research in karst hydrology, the "third wave" which is just beginning to gain momentum on the horizon.) In their preface to this volume, the editors point to the recent surge in interest in fractured rock hydrology, driven primarily by the search for appropriate sites for radioactive waste disposal, and proclaim that "the time is ripe to put together the main ideas and methodologies ... on flow and tracer transport in fractured rock domains...." Perhaps "compilers" would be a better word than "editors," for as they themselves state, "we have decided not to excessively edit or unify the chapters." Because of this decision, the resulting volume suffers from disjointedness, redundancy, inconsistency in notation and terminology, and an overall lack of structure. This is not a book to read cover-to- cover, nor a comprehensive survey to serve as a graduate-level text. Nevertheless, sections of the book are excellent, and the interested and determined reader will find many gems within.

The book consists of nine chapters on various topics related to fracture hydrology, each written by one or more acknowledged experts in their field. The chapter titles are intentionally broad and the chapters quite lengthy, ranging from 30 to over 100 pages. Most of the authors chose to begin with basic concepts and terminology for fractured rock systems. From a positive viewpoint, this means that as the editors point out, each chapter is relatively self-contained and can be read in any order; the downside is that a number of topics, including REVs, scaling,

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fracture roughness, the Stripa experiment, and the fractal nature of fractures are discussed repeatedly in multiple chapters. For students new to the subject this repetition may be helpful (or confusing), while most readers will find themselves skipping large sections of the text.

Since each chapter resembles an independent monograph, I shall describe each briefly. These descriptions follow the chapter order from the book, which is not the order I would recommend to the reader. Chapter 1, entitled "Modeling Flow and Contaminant Transport in Fractured Rocks," begins with a detailed set of defini- tions and a discussion of the Representative Elementary Volume (REV) for a fractured medium, and then moves into a lengthy mathematical analysis of flow and transport under a variety of saturated conditions. Readers for whom differential equations do not come naturally may agree with me that this was an unfortunate choice for what should have been an introductory chapter.

Chapter 2, "Solute Transport in Fractured Rock--Applications to Radionu- clide Waste Repositories," provides a good introduction to the major concepts and current research areas in fractured rock hydrology, from an applied point of view. The chapter opens with a description of the various nuclear waste repository programs around the world that are driving much of today's research, introduces the REV concept, and discusses a number of active research topics, including scale-dependent dispersion, matrix diffusion, and channeling within a single frac- ture. The emphasis on applied work continues with excellent descriptions of a number of key laboratory and field experiments. The author demonstrates the importance of scale fracture flow and transport as he moves from single-fracture tracer tests in the laboratory to the Stripa tracer test and the Fannay-Augeres field study with its 50 m long boreholes.

The authors of chapter 3, "Solute Transport Through Fracture Networks," are also interested in the effects of scale, but approach the problem from a more theoretical point of view. They begin with transport in a single fracture, then discuss mixing at the intersection of two fractures, which then naturally moves on to mixing in a network of many discrete fractures within an impermeable matrix. They demonstrate how random fracture networks lead to a macroscopic "effective anisotropy" and "effective dispersion," which enable a transition from computa- tionally intensive discrete fracture models to continuum models that include these "effective" parameters.

Chapter 4, "Stochastic Models of Fracture Systems and their Use in Flow and Transport Modeling," discusses the randomized discrete fracture networks intro- duced in the previous chapter in much greater detail. The authors emphasize that the purpose of these networks is to simulate actual field fracture patterns, and begin the chapter with an excellent introduction to field observation and statistical analysis techniques for real-world fractures. After collecting and analyzing field data, the next step is producing "synthetic" fracture networks that reflect the observations but are amenable to computer modeling. The authors describe a

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variety of network simulation techniques, beginning with the simplest random plane models and then adding additional complexity step by step with finite fracture discs, fractal approaches, geostatistical distributions, and finally complex hierarchical fracture cluster models. As the authors demonstrate, any of these network models can be conditioned to actual observations. After development of the fracture network, the next step is to model flow through the network. Like the authors of the previous chapter, the authors of chapter 4 begin with flow and transport in a single fracture, then move on to connectivity of multiple fractures in a network and an introduction to percolation theory. Assuming a connected network exists, flow can be modeled analytically, numerically, or using hybrid "channel" models. Since the network is a single realization of a random process, the geostatistical concepts of stationarity and ergodicity must be considered, and the REV concept is intro- duced once again. Finally, transport can be superimposed on the flow model, which adds the complexity of microdispersivity (as opposed to the macrodispersion caused by the fracture network) and matrix diffusion. This chapter is extremely well organized, clearly written, and well worth reading,

Chapter 5, "Tracer Transport in Fracture Systems," is a very brief introduction to three topics: transport through a single fracture with geostatistically variable aperture, an extrapolation to a three-dimensional fracture network, and an analysis of the Stripa study described at greater length in chapter 2. This chapter is written at a more elementary level than the other chapters in the book, and would make an excellent standalone introduction to fracture studies for a lower-level graduate course.

The authors of chapter 6, "Multiphase Flow in Fractured Petroleum Reser- voirs," begin their chapter with a literature review of the extensive petroleum research in this field, much of which is likely to be unfamiliar to practicing hydrologists. Once again, we find that reservoir engineers and hydrologists have been working on the same problem for years, using different terminology and notation. In their description of petroleum research, the authors introduce two important factors that the previous authors have neglected: multiphase flow and thermal effects. While both are key in reservoir engineering (multiphase flow can include oil-water and oil-water-gas systems, while thermal effects play an important role in steam floods), they are also important in hydrologic applications (where multiple phases can include nonaqueous phase liquids at contamination sites or air in the vadose zone, and thermal loading is an important factor at proposed high-level waste repositories). The authors describe a number of mathematical formulations for different scenarios, and then discuss the numerical "nuts and bolts" that enable the transition of these formulations into practical working models. The chapter closes with a brief treatment of a number of complicating factors, including matrix-fracture transfer functions, fracture compressibility, rela- tive permeability, and capillary effects.

Chapter 7, "Unsaturated Flow in Fractured Porous Media," focuses on a specific case of multiphase flow in which the two fluid phases are water and air.

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There is no escaping the fact that the primary impetus for research in this field is the US Department of Energy's Yucca Mountain Site Characterization Project (YMP), evaluation of a potential high-level nuclear waste repository in the unsatu- rated fractured tuff of Yucca Mountain, Nevada, and the authors begin their chapter with a brief history of the Project. The second section of the chapter describes the authors' conceptual model for unsaturated flow in fractured tuff, dwelling at length on the variable aperture fracture introduced in chapter 5. A particularly interesting feature of the conceptualization is a drastic change in the behavior of the fractures as moisture content changes. At saturated or near-satu- rated conditions, the fractures serve as active and primary conduits for flow, while under unsaturated conditions the fractures become passive dry pores and flow is primarily restricted to the matrix. After this discussion of unsaturated fracture flow in general, the authors focus in on specific conditions at Yucca Mountain. They describe the results of three major modeling efforts: a one-dimensional analysis of column drainage, a more complex large-scale two-dimensional analysis of the effects of stratigraphy, dipping beds and episodic rainfall at Yucca Mountain, and finally the effects of the Ghost Dance Fault, which cuts through the proposed repository. This chapter provides an excellent overview of the science coming out of YMP, but may be too site-specific for the reader looking for more general information on unsaturated fracture flow.

Chapter 8, "Simulation of Flow and Transport in Fractured Porous Media," begins with a thorough and extensive literature review of fracture flow research to date in five different fields: oil reservoir engineering, groundwater flow, contaminant transport, geothermal engineering, and soil physics. The authors point out how much duplication of effort and lack of communication has occurred among these disciplines. Common to all analyses is a primary distinction between discrete fracture modeling and equivalent continuum modeling. The authors present various analytical and numerical approaches to modeling flow and transport under each approach. Similar to chapter 1, this chapter is primarily theoretical in nature, with no experimental results or case study descriptions.

Chapter 9, the final chapter in the volume, is entitled "A Summary of Field Test Methods in Fractured Rocks." This chapter stands out by being by far the longest chapter in the book, and quite different in subject. As the title suggests, this chapter presents an exhaustive description of numerous field investigation techniques, including remote sensing, well logging and imaging, hydraulic tests, tracer tests, thermal methods, seismic methods, electrical investigations, electromagnetic sur- veys, gravitational surveys, and magnetic surveys. The chapter concludes with two case studies: engineering work for dam siting, and wireline logging in petroleum engineering. Unfortunately, another way this chapter stands out from the rest of the book is a prevalence of typographical errors, language difficulties, and confusing, poorly explained figures. (The rest of the book is strikingly free of such difficulties.) If a knowledgeable reader is looking for additional information on a specific topic,

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this chapter may provide useful references, but the general reader is likely to find this chapter frustrating.

Standard advice to a writer in any field is to begin with a strong introduction and to end with a strong conclusion. Unfortunately, the first and last chapters of this book are among the weakest. Despite these weaknesses, the reader who skips around the book, sampling some of the other chapters and making use of the extensive index will find much of value. In particular, chapter 5 provides an introductory-level overview of the field, chapter 4 an excellent and thorough treatment of stochastic modeling methods for fractured rock, and the literature review in chapter 8 reveals the broad interdisciplinary nature of the subject. The specific laboratory and field studies described in chapters 2 and 7 demonstrate the real-world importance of fracture-rock hydrology.

H. J. Turin Earth and Environmental Sciences Division Los Alamos National Laboratory Los Alamos, NM 87545, U.S.A.

Environmental Geophysics: A Practical Guide by Dieter Vogelsang, Springer, 1995; DM 98.00, 6s 764.40, sFr 94.50.

Professor Vogelsang's book is, to my knowledge, one of the first to specifically address the application of geophysical techniques to environmental problems. It is aimed at the nonspecialist, i.e., engineers, scientists, and nontechnical people such as lawyers who are involved in the environmental field who need to understand the potential of geophysical techniques in assessing environmental hazards.

After a short introductory chapter, the book gives an overview of the various geophysical methods used in the environmental field. The discussion is brief and, in general, presents a good summary of the basic applicability and limitations of each technique. However, readers wanting a more in-depth discussion, including the underlying theory of the various methods, must refer to other textbooks on applied geophysics.

The next chapter, which in my opinion is the strongest, describes several case histories. The author uses numerous figures from these case studies to illustrate the applicability of the various techniques to both the investigation of abandoned

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hazardous waste sites and the investigation of new disposal sights. Typically, the author combines the results of each technique with a schematic diagram illustrating the subsurface conditions. This allows the reader to relate a particular geophysical anomaly to a corresponding subsurface condition, thereby gaining an understand- ing of the interpretative nature of geophysical prospecting. These case studies are gathered from numerous sources, including the "gray" literature of technical reports, which is often difficult to access. The fact that such material is assembled in one book is a distinct advantage.

The next three short chapters describe some of the more practical aspects of geophysical investigations, such as planning surveys, cost estimates, and obtaining geophysical tenders. This type of information is typically not found in textbooks and is usually only encountered by those geophysicists working directly in the environmental field. The fact that it is included here allows both the nonspecialist and the students in geophysics to obtain an understanding of these practical considerations.

The final two chapters contain a list of the figures, tables, and references. One of the disadvantages of the reference list is the fact that most of the cited work is from unpublished technical reports, and about one-third of the references are German-language publications which are essentially inaccessible to the English- speaking audience. However, this criticism may be unjustified, because environmen- tal geophysics is a relatively young discipline which has grown rapidly in the last few years, and a strong publication base in peer-reviewed scientific journals has yet to be established.

Finally, I have some general comments on the book. First, there are several typographical errors. For example, on page 9, the symbol r is used to denote the specific resistivity but p is used in the formula. Similarly, on page 28, the symbol e is used for the dielectric constant but K is used in the table on the following page. Such errors are confusing, especially to nontechnical people. In addition, I feel that there are some editorial changes that could be made. For example, there are several instances where many one-sentence paragraphs could be combined into one para- graph to greatly improve the readability.

Despite these few shortcomings, I recommend the book. The target audience of nongeophysicaI environmental specialists should find the information valuable, and portions of the book, especially the case studies and the description of how to plan geophysical surveys, can provide valuable supplementary material for a more technical course in environmental geophysics or applied geophysics.

Robert D. Cicerone 19 Greenwood Avenue Dedham, MA 02026-5101 U.S.A.

Vo[. 146, 1996 Book Reviews 203

Climate Change in Continental Isotopic Records, eds. P. K. Swart, K. C. Lohmann, J. McKenzie, and S. Savin, Geophysical Monograph, v. 78, American Geophysical Union, Washington, 1993; US $57.00, AGU members US $39.90.

The seventy-eighth volume of the renowned Geophysical Monograph series contains thirty-one papers which are the result of an AGU Chapman Conference on Continental Isotopic Indicators of Climate (CIICs) held in Jackson Hole, Wyoming between June 10 and 14, 1991.

As pointed out by the editors, "this volume is designed to provide paleoclima- tologists with information on past climate from sources other than the deep-sea." Records from the marine environment, as provided by the isotopic composition of benthic and planktonic foraminifera, have been to date the traditional source of information on past climate changes. Though the climate variations recorded in marine environments are believed to reflect global environmental changes, other sources of information are needed to better understand the climatic variability found in continental interiors. This is particularly evident as current global climate models are unable to accurately predict observed continental temperature patterns.

The volume is divided in four main sections, dealing with hydrology, lacustrine environments, regoliths, and organic materials. These four groups are not compre- hensive of all possible types of CIICs, but they are nonetheless representative of the most widely applied CIICs. A series of seven papers dealing with the hydrological cycle initiates this volume. Because most of the materials used as CIICs have acquired their isotopic signature from the fluid in which they formed, knowledge of the processes determining the partitioning of stable isotopes among the different reservoirs of the hydrological cycle is crucial for the interpretation of continental isotopic records. This is the subject of the first four papers of this section (Rozanski et al., Grootes, Ingraham and Craig, Naftz et al.), which describe the isotopic composition of modern precipitation (also in the form of snow and ice) and associated surface and groundwaters. The hydrogen and oxygen isotopic signatures of natural waters can be related to parameters such as temperature, latitude, altitude and atmospheric circulation patterns. The compilation and interpretation of isotopic data from the various components of the modern hydrological cycle provide a base in which to infer climatically relevant data from the geologic record. The following two studies then focus on the use of oxygen and carbon isotope data from carbonate precipitates (calcretes: Rossinsky and Swart; meteoric calcite: Smith and Doborek) to reconstruct past changes in climatic conditions and the hydrological cycle. Climatic inferences are based on the fact that the isotopic composition of these carbonates reflect both the temperature of precipitation and the isotopic composition of local fluids. Both these parameters are climate dependent. The very interesting and also last paper of this section, devoted to the hydrological cycle (Stute and Schlosser), shows how noble gas (Ne, Ar, Kr, Xe) concentrations in groundwater systems of known age can be applied to derive paleotemperature information.

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The second section, which comprises nine papers, investigates the isotopic signatures found in lacustrine environments. In analogy to the ocean, lakes can provide both planktonic and benthic isotopic records. The former are obtained from the analysis of authigenic and biogenic carbonates precipitated in the photic zone and the latter from biogenic carbonates formed on the lake bottom. Further- more, lakes represent the link between precipitation and sediments, i.e., between the atmosphere and the geologic record. Four contributions to this section (Chivas et

al.; Curtis and Hodell; Palacio-Fest et al; Rogers) focus on the use of ostracod shells for paleoenvironmental reconstruction. Stable isotope of carbon and oxygen as well as trace elements (Sr, Ca, Mg) are applied to infer past changes in lake temperature and salinity associated with climate change. The oxygen isotopic composition of carbonates recovered from sediment cores (Hollander and McKen- zie; Leyden et al.), is another very powerful tool which can be applied to assess past changes in the chemical and physical state of a lake. Casanova and Hillarie-Marcel use very detailed oxygen isotope records obtained from lacustrine stromatolithes to provide high resolution records of hydrological changes in paleolakes. Other biological indicators have been used by Dettman and Lohmann (bivalves) and Patterson et al. (aragonitic otoliths of freshwater fishes) to extract climatic informa- tion from lacustrine systems.

The third section covers the isotopic composition of so-called regoliths, which include weathering and alteration products such as soils, calcretes, clay minerals, oxides, and volcanic glasses. Ten papers are dedicated to these potential indicators of climate. The first three papers of this section (Cerling and Quade; Kelly et al.;

Wang et al.) deal with the stable carbon and oxygen isotopic composition of soil carbonates. They explore the relationship between the isotopic signal and ecological and climatic variables, and conclude that pedogenic carbonates provide an excellent proxy for environmental change on continents. Three contributions (Lawrence and Rashkes Meaux; Yapp; Bird et al.) investigate the oxygen and hydrogen isotopic composition of authigenic minerals formed in continental environments character- ized by strong chemical weathering (e.g., kaolinite, goethite, and gibbsite). One study is dedicated to D/H ratios of supergene alunite (Arehart and O'Neil), whose most common form is represented by weathering products of highly pyritic rocks. The variations in 3D of the hydroxyl hydrogen in alunite are thought to reflect changes in the isotopic composition of meteoric waters and thus of climatic conditions. The last two papers of this section, both by Friedman et aI., describe the use in paleoclimate studies of secondary water in hydrated volcanic glasses. Because the hydration water is related to ancient precipitation, paleoclimatic inferences can be drawn from the analysis of its isotopic composition.

The final section, five papers in total, is devoted to the isotopic composition of organic materials, both of terrestrial and aquatic origin. The isotopic signals preserved in organic remains contain important information about the isotopic composition of the environmental water associated with tissue synthesis. Variations

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in the oxygen and hydrogen isotopic composition of organic matter strongly depend on isotopic fractionation effects occurring in the hydrologic cycle. Because changes in the hydrologic cycle reflect climate changes, variations in the isotopic composi- tion of organic matter can be applied as a proxy for climatic signals. These five papers consider isotopic data obtained from wood and fossil plant matter (Ed- wards; Jirikowic et al.; Leavitt), peat bogs (Aucour et al.), as well as from complex organic compounds such as chitin and amino compounds (Schimmelmann et al.).

Overall, this volume of the Geophysical Monograph series provides an excellent review of the current state of research on continental isotopic indicators of climate. The general level of the papers is such that both researchers with ample experience in isotope geochemistry and those just seeking a broad overview on this particular topic, will find this book of great value.

Andrea Lini Stable Isotope Laboratory Department of Geology Universigy of Vermont Burlington, VT 05405-0122 U.S.A.