The high pressures necessary for the stabilisation of eclogites in metabasic rocks andgarnetperidotitesinultrabasic rocks havebeen long recognised and experimentally established. Xenoliths of such rocks brought up in volatile charged alkaline magmas, such as kimberlites, are widely accepted to be mostly ofupper mantle derivation (Chapter 13). Eclogites are predicted to be thermodynamically stable also in the lower crust beneath cratonic regions. However, xenolith suite studies indicate that kinetic and/or compositional factors limit their distribution in the lower continental crust relative to granulite fades assemblages (Chapter 12). Occurrences ofeclogitesand gamet peridotites in exposed crustal metamor phic terrains have been interpreted in the past as exotic tectonic blocks of deeper (largely mantle) origin, because of their apparent difference in metamorphic grade compared with the encompassing rocks. Only in recent years have metamorphic petrologists begun to recognise that such crustal terrains sometimes preserve co-facial (eclogite fades), high pressure mineral parageneses in other spatially associated lithologies such as metapelites and metagranitoids. Placed in a modern, global geotectonic context, it is now apparent not only that eclogites can be expected to be stabilised in oceanic crust subducted at continental plate margins (Chapter 9), but also that eclogite fades mineral parageneses may be stabilised in a wider range ofcontinental crust lithologies, where substantial tectonic thickening has occurred in continental plate collision zones (Chapters 8-10). Recent exciting evidence from the Western Alps(Chapter 10)suggeststhat continental crust may be subducted to depths approaching 100km and iyet exhumed during subsequent orogenic uplift.

Metamorphic rocks are one of the three classes of rocks. Seen on a global scale they constitute the dominant material of the Earth. The understanding of the petrogenesis and significance of metamorphic of geological education. rocks is, therefore, a fundamental topic There are, of course, many different possible ways to lecture on this theme. This book addresses rock metamorphism from a relatively pragmatic view point. It has been written for the senior undergrad uate or graduate student who needs practical knowledge of how to interpret various groups of minerals found in metamorphic rocks. The book is also of interest for the non-specialist and non-petrolo gist professional who is interested in learning more about the geolo gical messages that metamorphic mineral assemblages are sending, as well as pressure and temperature conditions of formation. The book is organized into two parts. The first part introduces the different types of metamorphism, defines some names, terms and graphs used to describe metamorphic rocks, and discusses principal aspects of metamorphic processes. Part I introduces the causes of metamorphism on various scales in time and space, and some principles of chemical reactions in rocks that accompany metamorphism, but without treating these principles in detail, and presenting the thermodynamic basis for quantitative analysis of reactions and their equilibria in metamorphism. Part I also presents concepts of metamorphic grade or intensity of metamorphism, such as the metamorphic-facies concept.

Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones. This volume contains a collection of contributions that were presented in June 2007 in Montpellier (France) during a conference that gave a state of the art panorama and discussed the perspectives about "Subduction Zone Geodynamics". The papers included in this special volume offer a unique multidisciplinary picture of the recent research on subduction zones geodynamics. They are organized into five main topics: Subduction zone geodynamics, Seismic tomography and anisotropy, Great subduction zone earthquakes, Seismogenic zone characterization, Continental and ridge subduction processes. Each of the 13 papers collected in the present volume is primarily concerned with one of these topics. However, it is important to highlight that papers always treat more than one topic so that all are related lighting on different aspects of the complex and fascinating subduction zones geodynamics.

The lattice-preferred orientation (LPO) of minerals is important for interpreting seismic anisotropy, which occurs in the Earth's crust and mantle, and for understanding the internal structure of the deep interior of the Earth. The characterization of microstructures, including LPO, grain size, grain shape, and misorientation, is important to determine the deformation conditions, deformation histories, kinematics, and seismic anisotropies in the crust and mantle The articles in this Special Issue prove that studies of LPO and microstructures of minerals and rocks are a major research area and provide a foundation for interpreting seismic anisotropy in the crust, mantle, and subduction zones. Therefore, the authors hope that this Special Issue encompassing recent advances in the measurement of LPOs of different minerals under various tectonic settings will be a fundamental and valuable resource for the readers and researchers interested in exploring the deformation conditions of minerals and rocks, as well as the interpretation of seismic anisotropy in the crust, mantle, and subduction zones.

Featuring over 250 contributions from more than 100 earth scientists from 18 countries, The Encyclopedia of Igneous and Metamorphic Petrology deals with the nature and genesis of igneous rocks that have crystallized from molten magma, and of metamorphic rocks that are the products of re-crystallization associated with increases in temperature and pressure, mainly at considerable depths in the Earth's crust. Entries range from alkaline rocks to zeolite facies - providing information on the mineralogical, chemical and textural characters of rock types, the development of concepts and the present state of knowledge across the spectrum of igneous and metamorphic petrology, together with extensive lists of both commonly used and little used terms and bibliographies.

Designed for the middle-level undergraduate geology major, this text incorporates both fundamentals and information on advances in our understanding of igneous, sedimentary, and metamorphic rocks. It provides an overview of the field of petrology and a foundation for advanced studies.