The Oligocene White River Group consists of the Chadron and the overlying Brule Formations in northwestern Nebraska. The Chadron Formation consists of alluvial and colluvial vitric mudstone beds, but in addition contains white persistent layers (purplish-white layers) that probably resulted from soil formation on vitric parent material. West of the current study area a basal sandstone facies of the Chadron is host rock for the Crow Butte uranium deposit. The Brule, which consists mostly of pedogenically altered alluvial and fluvial vitric mudstone deposits, contains a uraniferous lacustrine facies northwest of Chadron, Nebraska.

Diagenesis affects all sediments after their deposition andincludes a fundamental suite of physical, chemical and biologicalprocesses that control the texture, mineralogy and fluid-flowproperties of sedimentary rocks. Understanding the processes andproducts of diagenesis is thus a critical component in the analysisof the evolution of sedimentary basins, and has practicalimplications for subsurface porosity destruction, preservation andgeneration. This in turn is of great relevance to the petroleum andwater industries, as well as to the location and nature of someeconomic mineral deposits. Combines key papers in sandstone diagenesis published inSedimentology over the last 30 years. Records the development of diagenesis from the description ofgrain shapes through provenance, petrography and analyticalgeochemistry to predictive models of diagenetic process. Provides definitions and explanations of the terms and conceptsused in diagenesis. If you are a member of the International Association ofSedimentologists, for purchasing details, please see:http://www.iasnet.org/publications/details.asp?code=RP4

Diagenesis in sediments

Clear writing and analysis of the broad spectrum of processes that produce shale are coupled with well-captioned 150 illustrations, 40 tables, boxed technical details, glossary and appendices. Recounts the step-by-step evolution and stages of shal, enabling readers to master the basics and to dig yet deeper into their origin, practical implications and relationship to earth history. Background information appears in appendices (Clay Mineralogy, Isotopes, Petrology, etc.); technicial details in high-lighted boxes, and definitions of 300+ terms in the Glossary.

This volume covers the formation and biogeochemistry of a variety of important sediment types from their initial formation through their conversion (diagenesis) to sedimentary rocks. The volume deals with the chemical, mineralogical, and isotopic properties of sediments and sedimentary rocks and their use in interpreting the environment of formation and subsequent events in the history of sediments, and the nature of the ocean-atmosphere system through geological time. Reprinted individual volume from the acclaimed Treatise on Geochemistry, (10 Volume Set, ISBN 0-08-043751-6, published in 2003). - Comprehensive and authoritative scope and focus - Reviews from renowned scientists across a range of subjects, providing both overviews and new data, supplemented by extensive bibliographies - Extensive illustrations and examples from the field

Carbonate Reservoirs: Porosity, Evolution and Diagenesis in a Sequence Stratigraphic Framework

Carbonate diagenesis is a subject of enormous complexity because of the basic chemical reactivity of carbonate minerals. These carbonate minerals react quickly with natural waters that either dissolve the carbonates, or precipitate new carbonates to bring the water into equilibrium with the host carbonate sediments and rocks. These rock-water interactions either create porosity by dissolution, or destroy porosity by the precipitation of carbonate cements into pore spaces. Carbonate Diagenesis and Porosity examines these important relationships in detail.This volume is published in co-operation with OGCI, and is based on training courses organised by OGCI and taught by Dr. Moore. It is intended to give the working geologist and university graduate student a reasonable overview of carbonate diagenesis and its influence on the evolution of carbonate porosity. It starts with a discussion of the major differences between carbonates and siliciclastics so that the novice will have an appreciation of the basic nature of the carbonate system. Carbonate porosity, its nature and its classification is then discussed so that the relationship between diagenesis and porosity can be established. Environments of diagenesis and their characteristics are outlined, stressing the nature of pore fluids found in each environment. Tools for the recognition of these environments are then discussed with stress on the constraints suffered by each technique. Each major diagenetic environment is then discussed in detail with petrographic, geochemical characteristics outlined, and an in depth discussion of the impact of the environment's diagenetic processes on porosity development and evolution. Diagenetic models are developed where appropriate and criteria for recognition listed. Case histories illustrating these concepts and models are presented for each major diagenetic environment and sub-environment.Over 160 line drawings illustrate the book. Petrographic characteristics of porosity and diagenetic fabrics and textures are illustrated using numerous photomicrographs taken specifically for the book by the author. The book has been extensively indexed, and includes a large, current reference section.This book should be useful to any geologist interested in, or working with, carbonate sediments and rocks. It will be particularly useful to the industrial geologist concerned with the exploration or exploitation of hydrocarbons from carbonate rock sequences where an understanding of porosity development, evolution, and prediction are important. In addition, this book will be a good text for advanced carbonate courses at graduate level, and an appropriate reference book for graduate students working in, or interested in, carbonate rock sequences and sediments.