Ultrahigh Pressure Metamorphism

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Ultrahigh Pressure Metamorphism

Author : Larissa Dobrzhinetskaya
ISBN : 0123851459
Genre : Science
File Size : 43.4 MB
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Ultrahigh Pressure Metamorphism (UHPM) is a fast growing discipline that was established 25 years ago after discoveries of high pressure minerals, coesite and diamonds. The current explosion of research on UHMP terranes reflects their significance for understanding large scale mantle dynamics, major elements of plate tectonics such as continental collisions, deep subduction and exhumation, mountains building, geochemical recycling 'from surface to the core', and a deep storage of light elements participating in green-house effects in the atmosphere. This book provides insights into the formation of diamond and coesite at very high pressures and explores new ideas regarding the tectonic setting of this style of metamorphism. Important, authoritative and comprehensive one-stop resource for the growing ultrahigh pressure metamorphism UHPM research community A forward-looking approach founded upon a detailed historical perspective on UHPM presents the trends in discovery, methodology and theory over the last 25 years, allowing readers to gain a clear understanding of the current trends and the approaches that will shape the science in the future A highly diverse set of articles, covering a wide range of methods and sub-disciplines
Category: Science

Petrology Of Ultrahigh Pressure Metamorphic Rocks From Pohorje Mountains

Author : Mirijam Vrabec
ISBN : OCLC:449363478
Genre :
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Ultrahigh-pressure metamorphism has been recorded in Eo-Alpine eclogites and garnet peridotites from the Pohorje Mts., Slovenia, belonging to the Eastern Alps. Eclogite bodies are hosted in continental crustal rocks, and are closely associated with meta- ultrabasic rocks, predominantly serpentinized dunites and harzburgites with garnet peridotite remnants. The eclogites contain a peak metamorphic assemblage of garnet, omphacite, kyanite and phengite. Pyrope-rich garnet is unzoned and almost free of inclusions. The non-stoichiometric supersilicic omphacites contain up to 5 mol% of Ca- Eskola molecule. Such clinopyroxenes are known to be stable exclusively at high- pressure conditions exceeding 3.o GPa. Their breakdown during decompression resulted in exsolution of quartz rods and needles that are oriented parallel to omphacite c-axis. Phengite contains up to 3.5 Si pfu. Polycrystalline quartz inclusions in primary minerals are surrounded by radial fractures and often exhibit microtextures diagnostic of the former presence of coesite. The absence of coesite is a consequence of near-isothermal decompression during the first stages of exhumation. Eclogites are rich in Mg0 and have Ca0and A1203 contents consistent with mafic magmatic rocks. They are more depleted than MORB with positive Sr and Pb anomalies, and with Cs, Rb, Ba enrichments. Precursor rocks were plagioclase-bearing (gabbroic) cumulates from depleted mantle- derived melts, which most probably formed in the Permiantime. Garnet peridotites show signs of a complex four-stage metamorphic history. The protolith stage is represented by a low-P high-T assemblage of olivine + Al-rich orthopyroxene + Al-rich clinopyroxene + Cr-spinel. Due to metamorphism, primary clinopyroxene shows exsolutions of garnet, orthopyroxene, amphibole, Cr-spinel and ilmenite. The UHP metamorphicstage is defined by the assemblage garnet + olivine + Al-poor orthopyroxene + clinopyroxene + Cr-spinel. Subsequent decompression and final retrogression stage resulted in formation of kelyphitic rims around garnet and crystallization of tremolite, chlorite, serpentine and talc. The garnet peridotites are relatively rich in A1203, Ca0 and Sr compared to primitive mantle, where as REE commonly show depleted patterns with positive Eu anomalies. Most probably garnet peridotites represent depleted mantle rocks that became refertilized within the plagioclase stability field before tectonic incorporation in the subducting continental slab, or, alternatively, they might carry the signature of metasomatism by melts derived from a plagioclase-bearing source, possibly even the eclogites. P-T estimates for eclogites and garnet peridotites indicate that the peak of metamorphism reached over 3 GPa and 800 °C in the eclogites and close to 4 GPa and 900 °C in the garnet peridotites, well within the UHP stability field. Eclogites and garnet peridotites did not share the same P-T path until the incorporation of peridotite from the mantle wedge into the subducting crust. The, rocks of the Pohorje Mts. record the highest-pressure conditions of all Eo-Alpine metamorphism in the Alps. Petrographic and geochemical evidence shows that these conditions were reached during deep subduction (at least 100 km) of continental slab. The southward increase inpeak pressure from approximately 2 GPa in the Koralpe and Saualpe to 3 or 4 GPa in the Pohorje suggests the south to south-eastern dip of the Cretaceous intra-Alpine subduction zone. Ultrahigh-pressure rocks of Pohorje were probably exhumed by ,slab extraction", that is, the downward removal of the mantle and lower crustal wedge overlying the subducted rocks.
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Ultrahigh Pressure Metamorphic Rocks In The Dabieshan Sulu Region Of China

Author : Po-lin Tsʻung
ISBN : STANFORD:36105018339312
Genre : Science
File Size : 90.88 MB
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Recent discoveries of diamond and coesite in the ultrahigh- pressure (UHP) metamorphosed supracrustal rocks have provoked a new challenge to present-day geodynamic ideas. A worldwide shift towards a new paradigm on the Earth's dynamics is imminent. Facing the new challenge, Chinese geologists have been taking an active role. The Dabieshan-Sulu region, the largest and best exposed UHP belt in the world, has attracted international attention. This comprehensive book describes many aspects of the UHP rocks in the Dabieshan-Sulu region, including the geotectonic setting, mode of occurrence, mineralogy and petrology, isotope chronology, major and trace element chemistry, and metamorphic PTt path. The possible geodynamic mechanisms involved in the deep subduction and rapid exhumation of UHP rocks are also discussed. This book will be of particular interest to researchers and graduate students of metamorphic petrology and global tectonics.
Category: Science

Ultrahigh Pressure Mineralogy

Author : Russell J. Hemley
ISBN : 9781501509179
Genre : Science
File Size : 28.2 MB
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Volume 37 of Reviews in Mineralogy, divided into three sections, begins with an overview (Chapter 1) of the remarkable advances in the ability to subject minerals-not only as pristine single-crystal samples but also complex, natural mineral assemblages-to extreme pressure-temperature conditions in the laboratory. These advances parallel the development of an arsenal of analytical methods for measuring mineral behavior under those conditions. This sets the stage for section two (Chapters 2-8) which focuses on high-pressure minerals in their geological setting as a function of depth. This top-down approach begins with what we know from direct sampling of high-pressure minerals and rocks brought to the surface to detailed geophysical observations of the vast interior. The third section (Chapters 9-19) presents the material fundamentals, starting from properties of a chemical nature, such as crystal chemistry, thermochemistry, element partitioning, and melting, and moving toward the domain of mineral physics such as melt properties, equations of state, elasticity, rheology, vibrational dynamics, bonding, electronic structure, and magnetism. The Review thus moves from the complexity of rocks to their mineral components and finally to fundamental properties arising directly from the play of electrons and nuclei. This volume was prepared for a short course by the same title, organized by Russell J. Hemley and Ho-kwang Mao and sponsored by the Mineralogical Society of America, December 4-6, 1998 on the campus of the University of California at Davis.
Category: Science

When Continents Collide Geodynamics And Geochemistry Of Ultrahigh Pressure Rocks

Author : Bradley Hacker
ISBN : 9789401590501
Genre : Science
File Size : 39.57 MB
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2Gpa has increased to more than 15. This indicates that subduction of continental fragments to depths of 100-150 km may have played a significant role in the formation of mountain belts. This volume brings together the geochemical, geophysical and geodynamical approaches to study the processes active during ultrahigh-pressure (UHP) tectonics. The collection of papers demarkates the frontier of our understanding of the creation, preservation, and exhumation of ultrahigh-pressure rocks. Audience: This volume will be of interest to any earth scientist interested in ultrahigh pressure processes and the formation and modification of continental crust.
Category: Science

Petrogenesis Of Metamorphic Rocks

Author : K. Bucher
ISBN : 9783662049143
Genre : Science
File Size : 77.84 MB
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Metamorphic rocks make up the largest volume of the Earth. They systematically change their mineralogical composition as a result of tecto-thermal events. The outstanding feature of the 7th edition of this book is the large number of phase diagrams showing the stability relations among minerals and groups of minerals found in metamorphic rocks. The diagrams help to determine the pressure and temperature conditions under which a given collected set of metamorphic rocks may have formed. More than half of the chapters have been completely rewritten or revised. All figures have been edited and improved and recent advances in the field such as multiequilibria thermobarometry and pseudosections were incorporated in the text. The bibliography has been revised and extended, new research publications have also been included. Graduate students will find in depth information on the origin, significance and genesis of metamorphic rocks.
Category: Science

Geochronology

Author : Derek Vance
ISBN : 1862391467
Genre : Science
File Size : 61.92 MB
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Category: Science

Petrogenesis Of Metamorphic Rocks

Author : Kurt Bucher
ISBN : 9783540741688
Genre : Science
File Size : 21.8 MB
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Petrogenesis of Metamorphic Rocks presents a large number of diagrams showing the stability relations among minerals and groups of minerals found in metamorphic rocks. The diagrams help to determine the pressure and temperature conditions under which a given set of metamorphic rocks may have formed. Other parameters that control metamorphic mineral assemblages are also discussed and pitfalls resulting from simplifications and generalizations are highlighted. The book discusses the most common metamorphic rock types, their nomenclature, structure and graphical representation of their mineral assemblages. Part I defines basic principles of metamorphism, introduces metamorphic processes, geologic thermometry and barometry and defines metamorphic grade. Part II presents in a systematic way mineralogical changes and assemblages found in the most common types of metamorphic rocks. The computation of diagrams is based on recent advances in quantitative petrology and geochemistry. An extensive bibliography, including the key contributions and classic papers in the field, make it an invaluable source book for graduate students and professional geologists.
Category: Science