The Origin of Clay Minerals in Soils and Weathered Rocks

verfasst von: Bruce Velde, Alain Meunier

Verlag: Springer Berlin Heidelberg

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

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.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Fundamentals of Clay Mineral Crystal Structure and Physicochemical Properties

Abstract

The word “clays” was assigned early to fine grained material in geological formations (Agricola 1546) or soils (de Serres 1600). Clays have been identified as mineral species in the begining of the 19th century in the production of ceramic materials (Brongniart 1844). Then Ebelmen (1847) carefully analyzed the decomposition of rocks under chemical attack and the way that porcelain can be commonly made. Since this pionner works, the definition of clays has varied. Until recently, the definition of clay minerals was debated. Bailey (1980) restricted the definition of clay to fine-grained phyllosilicates. Guggenheim and Martin (1995) considered that clays are all the finegrained mineral components that give plasticity after hydration to rocks or materials which harden after drying or burning.

Bruce Velde, Alain Meunier

Chapter 2. Basics for the Study of Soil and Weathered Rock Geochemical Systems

Abstract

Clays minerals form and transform in many different environments at the Earth’s surface or sub-surface such as soils, weathered rocks, oceanic and continental hydrothermal systems, sedimentary layers or diagenetic series. Whatever the environments, the common point is that aqueous solutions are always present and interact with rocks where clay minerals form. These solutions may be cold (few degrees at the ocean bottoms) or very hot (above 300 °C in the deep zones of hydrothermal systems). They may be diluted (meteoric water) or highly concentrated (brines). In all the cases, clay minerals adjust their composition and their crystal structure to the local conditions where they form or transform.

Bruce Velde, Alain Meunier

Chapter 3. The Development of Soils and Weathering Profile

Abstract

Weathering processes and soil development have been classically considered as two aspects of a single phenomenon which is the transformation of rocks under climatic conditions (meteorization). White (1995) gave a clear definition of what is classically considered as a soil profile: “The soil profile is generally considered to make up the upper part of a much thicker weathering profile. A more inclusive definition of a soil profile is the vertical section that includes all the layers that have been pedologically altered during chemical weathering. Soil horizons defined within such profiles clearly recognize the vertical transition in the degree of weathering from the intensively altered A and E horizons through the moderately weathered B, to the relatively unaltered C horizons to bedrock (Buol et al. 1989).

Bruce Velde, Alain Meunier

Chapter 4. Clay Mineral Formation in Weathered Rocks: Water/Rock Interaction

Abstract

The greatest part of the geological formations are altered when outcropping. Formed under temperature, pressure and chemical conditions different from those prevailing at the interface with the atmosphere, the rocks are transformed into a softer material. Their physical and chemical characteristics are changed because new minerals are formed, new passageways for water are opened and most of the chemical components are leached out. The altered mantle is in its turn covered by soils when the climatic and topographic conditions are favorable for the life of plants and trees. During and after their life, these organisms locally modify the chemical conditions (pH, complexation) at the rock-atmosphere interface inducing specific mineral reactions. The macro- and microbial activity contributes to chemical exchanges with the atmosphere. The result is the SOIL.

Bruce Velde, Alain Meunier

Chapter 5. Plants and Soil Clay Minerals

Abstract

A brief review of clay mineral assemblages in weathering profiles indicates that the upper-most zones (A horizons for the most part) contain species that are not present or less represented in the layers below, the alterite or C horizon. This is indicated in Chap. 3. If there is a difference in the A horizon mineralogy, it must be either due to a higher intensity of weathering due to rainwater and clay interaction, or to the influence of the chemistry engendered by plants on clay minerals. Since there is rarely an indication of more highly weathered minerals in the A horizon, such as gibbsite, one might suspect that the influence of plants can account for the differences in clay assemblages between A and C (alterite) horizons. We would like to investigate this possibility using studies based upon time which demonstrate the dynamics of plant–clay interaction.

Bruce Velde, Alain Meunier

Chapter 6. Clays and Climate – Clay Assemblages Formed under Extreme Humidity Conditions

Abstract

Generally when one considers alteration sequences one thinks of climates and conditions common to one’s environment; i.e. inhabited, agricultural areas. However some climatic conditions create special chemical systems where specific minerals form due to the climate, i.e. variations of total rainfall and rainfall distribution throughout a yearly cycle. Of course one can consider glacial conditions as a climate. But given that very little of the yearly interaction with rock and atmosphere occurs under conditions of liquid water/rock interaction, this climatic possibility is ignored here. Very cold, tundra, climates tend to be more assimilable to those of temperate climate systems but these systems operate only part of the year and biological activity is weak.

Bruce Velde, Alain Meunier

Chapter 7. Physical Disequilibrium and Transportation of Soil Material

Abstract

Surface movement of geological materials is a very important factor in interpreting clays at the surface. Much of what we see today at the surface has been displaced from its initial position of contact with the atmosphere to the site where it is now. This is in fact one of the major problems of interpreting soils and soil clay relations and has been known and studied for many years by pedologists. Multi cycle surfaces are very often sites of human activity. For example, the initial great civilizations were produced on sites of fluvial transport. Ancient Egypt was renowned for the Nile River and its regular flooding and subsequent fertile renewal of surface soils. The Tigris and Euphrates flood plains were sites of soil renewal. The Ganges flood plain is continually fertile. Xian in the old cradle of Chinese civilization was at the same time subject to active loess deposition and river flooding.

Bruce Velde, Alain Meunier

Chapter 8. The Place of Clay Mineral Species in Soils and Alterites

Abstract

Throughout the book thus far one can find the crystallo-chemical descriptions of clay minerals, their specific chemical properties as well as the probable reasons for their formation and lack of crystal size development. The transformation of unstable high temperature minerals into clays by the interaction of meteoric water and rock silicate minerals producing fine-grained crystallites is given in detail. These are the classical accounts of clay mineral formation under the influence of surface water-rock interaction. They depend essentially on the ratio of water to rock or altering mineral during the reaction period. Clay minerals formed at the rock interface are present in the saprock and eventually saprolite zone, and they are eventually submitted to the direct interaction of meteoric water at the soil surface in the context of plant/silicate interaction chemistry. Attention has been drawn to the importance of plants on clay mineral stabilities and occurrences.

Bruce Velde, Alain Meunier

Chapter 8. The Place of Clay Mineral Species in Soils and Alterites

Abstract

Bruce Velde, Alain Meunier

Backmatter

Titel: The Origin of Clay Minerals in Soils and Weathered Rocks
verfasst von: Bruce Velde
Alain Meunier
Verlag: Springer Berlin Heidelberg
Electronic ISBN: 978-3-540-75634-7
Print ISBN: 978-3-540-75633-0
DOI: https://doi.org/10.1007/978-3-540-75634-7