Alain Meunier - Böcker

This monograph discusses the major problems relating to the surface environment by using clay mineralogy as a unifying theme. Since the stability and development of illite, the most abundant and most common clay mineral, is the key to surface mineral dynamics, understanding its structure and transformation is an absolute prerequisite to understanding the problems of environmental change. Using illite as the frame, the authors describe problems in soil chemistry, clay stability and clay kinetics in sedimentary rocks. This book is valuable for graduate students, scientists and researchers in the fields of sedimentology, sediment petrography and soil sciences.

presents the fundamentals of the mineralogy and geology of clays through clear explanations of the mineralogical and geological problems involving clay minerals. It first introduces key concepts (crystallography and mineralogy of clays, thermodynamics, isotope chemistry, surface physical properties), setting the stage for readers to learn how clay minerals are formed or transformed in the principal geological environments at the Earth�s surface. Abundant illustrations, short paragraphs, exercises and applications support the comprehension of key concepts underlying crystallography, chemical reactions and geological situations. Theoretical demonstrations are reduced to the minimum necessary to grasp the fundamentals. Aimed for graduate students and scientists (geologists, geographers, engineers, environmental and soil scientists), "Clays" provides a comprehensive introduction to an important geological topic.

Of course such a book as we propose here is not the product of just two people working together, although the experience has been a great pleasure for us. We would like to thank our many collaborators and students who have encouraged our effort by their, often, sharp criticism. We hope that we have used their comments to good effect. Es- cially we would like to thank Pierre Barré for his help, enthusiasm and consent for the use of much of his thesis material in formulating the last chapter of the book. Dominique Righi was instrumental in giving us ideas, useful comments and vigorous debate for a great number of our ideas and during the periods of formulation of our conclusions. Our approach is from mineral chemistry and hence has greatly benefited from disc- sions with people who know soils and plants. The project of this book was realized and encouraged with the help of Wolfgang Engel who, unfortunately is not with us to see its finalization. We greatly regret his passing. This book is not in the general pattern of accepted knowledge and analysis of the phenomena which affect the occurrence of clays in the surface environment. We stress the role of plants at the bio-interface and the importance of microsystems at the water/ rock interface. We believe that the literature at our and anyone’s disposal shows that the system of clay formation and reaction is highly dynamic, especially at the surface.

It is our pleasure to present this large body of information and thoughts of many mineral scientists which has accumulated over decades. Illite is a mineral that has been discovered relatively recently, even though it has great importance in the geological cycles of weathering, sedimentation and burial. Illite is the major potassium mineral among silicates in the surface environment. Potassium represents the only alkaline metal, to be bound in silicate structures during the great chemical reshuffling called weathering. The weathering environment is one of strong chemical segregation, where Si and AI become the resistant, of silicate rocks. Iron forms an oxide and potassium forms residual elements the stable clay illite. Then Si and Al form smectites and kaolinite. Sodium, calcium and to a large extent magnesium are extracted from the solids as dissolved ionic species of the altering fluids. Ca and Mg are reintroduced into solid minerals via carbonate precipitation, and Na remains to make the sea saline. This mineral has been difficult to study because it is of fine grain size, as are all clays: 2 pm in diameter. Illite, along with other clays, had to wait to be discovered until a useful method of X-ray detection became available. With such a tool clays, whose definition was initially based upon the resolving power of an optical microscope (2 ]. lm), could be efficiently investigated. In fact the study of illite parallels the use and development of X -ray diffraction techniques.

This book is about the most complete work on the subject of clay minerals thus far conceived. Its scope is one of basics to general principles to use in real geologic situations. In principle any student, advanced student or casual researcher, should be able to ?nd an answer to almost any question posed. The breadth of knowledge presented is truly impressive. This presentation is especially important at present when the study of the most abundant minerals found near the Earth’s surface, clays, appears to ?nd disfavour with students and Universities. In fact we have never before needed such an encyclopaedic work to strengthen the discipline. At present when Earth sciences are slowing in popularity, the need for a precise and general education in the study of clay minerals is greater than ever before. Curiously the study of the environment, those materials found in the sphere of biological activity, is more relevant than ever. The natural progress of human activity through the age of science and then industrial activity up to the present stage of the post-industrial era has been marked by an increasing use of the Earth’s surface resources. The steady increase of the human population has called upon the natural resources of the surface in a non-linear manner. In the pre-industrial era agriculture and industry was concerned with the basic subsistence of populations. In good years there was enough to eat and in bad ones not enough.