Archaean Geochemistry

Archaean Geochemistry 1972 - 1984 The realisation that the continental crust contains well-preserved relics which date as far back as 4/5 of the Earth's age has given a great impetus to the study of early Precambrian terrains. As late as the mid-sixties the Archaean still constituted the 'terra-in cognita' of earth science. High metamorphic grades, poor out crop, and not least a widely assumed obliteration of early crustal records by convective recycling and thermal reworking had com bined to discourage research in this field. Many excellent local studies existed, notably around gold mining centres, but remained unrelated to a broader regional and theoretical understanding. This situation has changed as the consequence of two inter-related factors: (1) advances in isotopic methods and their application to Precambrian rocks, and (2) the recognition that some of the oldest terrains have retained a wealth of primary igneous and sedi mentary textures and even geochemical characteristics.

This book provides a comprehensive overview of the evolution of one of the oldest and best-exposed Archaean cratons on this planet. There is currently a renewed interest in the early Earth, and the Kaapvaal craton has long served as a model for early crustal evolution. This unique multidisciplinary resource features information on geology, tectonics, geochemistry, and geochronology. It offers a wealth of new data on various aspects of the craton as well as contributions on the various crustal units by international specialists.

Archaean terrains contain a wealth of structural, stratigraphic, textural, mineralogical, geochemical and isotopic features allowing insights into the nature of the early Earth. This book is based on studies during 1964-2007 of Archaean terrains in Australia and to a lesser extent in South Africa and India, as well as on visits to Archaean terrains in Canada, the US and China, as well as petrological and geochemical studies of igneous and sedimentary rock suites from a range of terrains. The book will include a range of photographic and microscopic images, geological sketch maps and diagrams illustrating the lessons derived from field and the laboratory. Also other Archaean terrains are being reviewed. The book is intended for Earth scientists as well as broader intelligent readership.

Volume 21 of Reviews in Mineralogy treats a short course on the rare earth elements to about 80 participants in San Francisco, California, December 1-3, 1989, just prior to the fall meeting of the American Geophysical Union. Contents: Cosmochemistry of the Rare Earth Elements: Condensation and Evaporation Processes Radiogenic Isotope Geochemistry of Rare Earth Elements Partitioning of Rare Earth Elements between Major Silicate Minerals and Basaltic Melts An Approach to Trace Element Modeling Using a Simple Igneous System as an Example Rare Earth Elements in Upper Mantle Rocks Rare Earth Elements in Metamorphic Rocks Rare Earth Elements in Sedimentary Rocks: Influence of Provenance and Sedimentary Processes Aqueous Geochemistry of Rare Earth Elements Rare Earth Elements in Lunar Materials Compositional and Phase Relations among Rare Earth Element Minerals Economic Geology of Rare Earth Minerals Cathodoluminescence Emission Spectra of Rare Earth Element Activators in Minerals

The integration of Tectonics/Geochemistry, up-to-date reviews by leading scientists as well as a broad topical coverage of the Archean, are some of the features of this particular volume. As geochronology has progressed in the last 20 years, the Archean has continued to attract interest. Advancements in the understanding of Archean crustal and mantle evolution have progressed rapidly since the first International Archean Symposium in Western Australia (1970). The landmark for the Archean was the NATO Advanced Study Institute at Leicester (1975). At this meeting the Archean truly "came of age". Investigators from many different disciplines focused their expertise on the early history of the earth. For the first time, the nature of the atmosphere, oceans, and life during the Archean was an important part of an Archean symposium. During the most recent Archean Symposium in Perth in 1990, there was a shift in interest from field and trace element data to the new rapidly evolving high-precision U/Pb geochronology of Archean rocks and to detailed structural studies of both low and high grade Archean terrains. The terrane concept so widely applied to the Phanerozoic was proposed for the Archean Yilgarn Province in Western Australia and is now widely accepted for the Archean (as evident by the articles in this book). Plate tectonics is now widely accepted as the principal process that controls the history of continents and oceans. There are, though, well substantiated differences between Archean and post-Archean rocks that indicate that Archean tectonic regimes must have differed in some respects from modern ones. The question of how and to what degree did Archean plate tectonics differ from modern plate tectonics is treated in many of the chapters of this book. Altogether, the editor has presented a selection of articles that provide a fascinating insight into the latest observations in this field.