Download or read book The Role of Partial Melting on Trace Element and Isotope Systematics of Granitic Melts written by Mathias Johannes Wolf and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Partial melting is a first order process for the chemical differentiation of the crust (Vielzeuf et al., 1990). Redistribution of chemical elements during melt generation crucially influences the composition of the lower and upper crust and provides a mechanism to concentrate and transport chemical elements that may also be of economic interest. Understanding of the diverse processes and their controlling factors is therefore not only of scientific interest but also of high economic importance to cover the demand for rare metals. The redistribution of major and trace elements during partial melting represents a central step for the understanding how granite-bound mineralization develops (Hedenquist and Lowenstern, 1994). The partial melt generation and mobilization of ore elements (e.g. Sn, W, Nb, Ta) into the melt depends on the composition of the sedimentary source and melting conditions. Distinct source rocks have different compositions reflecting their deposition and alteration histories. This specific chemical “memory” ...

Download or read book Mantle Xenoliths written by Peter H. Nixon and published by John Wiley & Sons. This book was released on 1987 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: The eruption of deep-seated xenoliths in basaltic, alnoitic, kimberlitic, etc volcanoes provides the geologist with an important direct means of examining the fragments of the earth's mantle and lower crust.

Download or read book Petrochronology written by Matthew J. Kohn and published by Walter de Gruyter GmbH & Co KG. This book was released on 2019-11-05 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: Petrochronology is a rapidly emerging branch of Earth science that links time (ages or rates) with specific rock-forming processes and their physical conditions. It is founded in petrology and geochemistry, which define a petrogenetic context or delimit a specific process, to which chronometric data are then linked. This combination informs Earth’s petrogenetic processes better than petrology or geochronology alone. This volume and the accompanying short courses address three broad categories of inquiry. Conceptual approaches chapters include petrologic modeling of multi-component chemical and mineralogic systems, and development of methods that include diffusive alteration of mineral chemistry. Methods chapters address four main analytical techniques, specifically EPMA, LA-ICP-MS, SIMS and TIMS. Mineral-specific chapters explore applications to a wide range of minerals, including zircon (metamorphic, igneous, and detrital/Hadean), baddeleyite, REE minerals (monazite, allanite, xenotime and apatite), titanite, rutile, garnet, and major igneous minerals (olivine, plagioclase and pyroxenes). These applications mainly focus on metamorphic, igneous, or tectonic processes, but additionally elucidate fundamental transdisciplinary progress in addressing mechanisms of crystal growth, the chemical consequences of mineral growth kinetics, and how chemical transport and deformation affect chemically complex mineral composites. Most chapters further recommend areas of future research.

Download or read book Monazite Control on Th U and REE Redistribution During Partial Melting written by Aleksandr Stepanov and published by . This book was released on 2012 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rare earth elements (REE), Th and U are elements with similar geochemical properties. In crustal rocks these elements are hosted by the light REE (LREE) phosphate mineral monazite. Piston-cylinder experiments were conducted to constrain monazite solubility and monazite/melt partitioning in hydrous granitic melts at conditions relevant to crustal anatexis and subduction zone melting. Monazite has strong preference for LREE and Th; REE heavier than Nd have decreasing compatibility in monazite, and U is less compatible than LREE and Th. New experimental data and reconciliation with previous studies led to a new formulation of LREE solubility in granitic melts as a function of temperature, pressure, monazite composition and water content in melt. The behaviour of monazite during high-pressure and ultra-high pressure (UHP) metamorphism was studied using a suite of rocks from the Kokchetav massif, Kazakhstan. Detailed petrographic and geochronologic study of the samples from the Kokchetav UHP complex was combined with investigation of trace element geochemistry and mineral inclusions of garnet, monazite and zircon. These data demonstrated that (a) on prograde evolution rocks did not experience a linear increase of pressure and temperature (P and T), but had stages of almost isothermal increase of pressure and heating stage with a small increase of pressure, (b) exhumation produced a close association of UHP gneisses with rocks that experienced metamorphism at lower PT conditions and/or along different paths from typical UHP rocks. The geochemistry of the UHP gneisses of the Kokchetav complex is a perfect target for the application of the new experimental data, because these rocks experienced metamorphism and melting at the highest PT conditions recorded in crustal rocks. Bulk rock geochemistry of the UHP gneisses shows pronounced depletion in LREE, Th and U, and a smaller degree of depletion or enrichment in other elements that are often considered as incompatible. The variation in composition of UHP gneisses is explained by a new petrological model, which takes into account the fact that restites are composed of residual assemblage together with a residual melt. It is demonstrated that together with the residual mineral association, the degree of melting and melt extraction efficiency play an important role in controlling of trace element behaviour. Polyphase inclusions trapped in garnet were found in samples of some UHP gneisses. The original composition of inclusions was obtained by high pressure rehomogenisation experiments. The experiments demonstrated that polyphase inclusions represent former melts of variable compositions, varying from high temperature high-LREE melts formed at peak conditions to low-LREE melts formed during exhumation. These inclusions are the first natural examples of melts formed by melting of sediments at subarc depth. This partial melting led to the complete dissolution of monazite and a strong depletion of LREE, Th and U in the UHP gneisses. Melt inclusions and bulk rock geochemistry provide evidence for the release of high LREE melts from melting of crustal metasediments. Partial melting is thus an important process changing the physical and chemical properties of deeply subducted crustal rocks.

Download or read book Using Geochemical Data written by Hugh Rollinson and published by Cambridge University Press. This book was released on 2021-05-06 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a complete rewrite, and expansion of Hugh Rollinson's highly successful 1993 book Using Geochemical Data: Evaluation, Presentation, Interpretation. Rollinson and Pease's new book covers the explosion in geochemical thinking over the past three decades, as new instruments and techniques have come online. It provides a comprehensive overview of how modern geochemical data are used in the understanding of geological and petrological processes. It covers major element, trace element, and radiogenic and stable isotope geochemistry. It explains the potential of many geochemical techniques, provides examples of their application, and emphasizes how to interpret the resulting data. Additional topics covered include the critical statistical analysis of geochemical data, current geochemical techniques, effective display of geochemical data, and the application of data in problem solving and identifying petrogenetic processes within a geological context. It will be invaluable for all graduate students, researchers, and professionals using geochemical techniques.

Download or read book Subduction Zone Magmatism written by Yashiyuki Tatsumi and published by Wiley. This book was released on 1995-06-15 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction zones are major sites of volcanism on the Earth. As one crustal plate sinks or is pushed beneath another, hot magma is produced and the resultant magma flux is fundamental to both the thermal evolution and chemical differentiation of the mantle and the Earth itself. To understand these evolutionary processes, we need to understand the physical and chemical consequences of all aspects of the subduction process. In this book, the authors present a simple, current and comprehensive model that explains the dominant geological processes at work in subduction zones. Structuring the book around the model, the authors describe the physical characteristics and geochemical dynamics of subduction zones, arc magma generation, and the dynamics and flow in the mantle. Students and researchers alike will find this book of immense value in understanding this most complex of subjects.

Download or read book Deep Carbon written by Beth N. Orcutt and published by Cambridge University Press. This book was released on 2019-10-17 with total page 687 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive guide to carbon inside Earth - its quantities, movements, forms, origins, changes over time and impact on planetary processes. This title is also available as Open Access on Cambridge Core.

Download or read book Vertical Coupling and Decoupling in the Lithosphere written by John Grocott and published by Geological Society of London. This book was released on 2004 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: " ... developed out of two symposia: 'Deformation at Convergent Margins', convened at the European Union of Geosciences meeting (EUG XI) at Strasbourg in April 2001; and 'Vertical Coupling and Decoupling at Convergent Margins', convened at the AGU Fall meeting in San Francisco in December 2001"--Acknowledgements.

Download or read book Himalayan Tectonics written by P. J. Treloar and published by Geological Society Publishing House. This book was released on 1993 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constraints on Mantle Melting from Major and Trace Element Systematics in Residual Abyssal Peridotites written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: AbstractThe generation of mid-ocean ridge basalts (MORB) is one of the most important mass transfer processes on Earth. Each year, more than twenty km3 of magmatic crust is produced along 75,000 km of ocean ridge, which is over ninety percent of the global magma production. Although ocean ridges and MORB are among the most studied geological features, several interlocking issues concerning melt generation at mid-ocean ridges are still not well understood. The most important of these are the role of geodynamic boundary conditions, such as spreading rate or vicinity to plumes and large transform offsets, as well as the absolute extent of melting or the depth at which melting initiates. This thesis examines these issues on the basis of mineral major and trace element compositions of oceanic mantle rocks. Geochemical characteristics of MORB suggest that melting begins in the stability field of garnet peridotite, at depths exceeding 80 km. Recent experiments, however, have shown that heavy rare earth elements (REE) are compatible in clinopyroxene (cpx) at the lherzolite solidus. This garnet-like partitioning behavior of cpx implies that garnet is no longer needed and that melting begins at significantly lower pressures. Therefore it is important to know, whether this hypothesis is consistent with compositional variations of abyssal peridotites. These fragments of the oceanic mantle are the residues of MORB melting and are now exposed on the ocean floor. Their mineral chemistry preserved the conditions at which melts were created in the mantle. Major and trace element data obtained by electron and ion microprobe on residual abyssal peridotite samples from the Central Indian Ridge (CIR) are compared to published data. Cpx in the CIR peridotites have very fractionated REE patterns, i.e. low Sm/Yb ratios, but high absolute Yb concentrations. Fractional melting models (which simulate the most extreme fractionation theoretically possible) of a spinel peridotite using commonly a.

Download or read book The Fourth Hutton Symposium on the Origin of Granites and Related Rocks written by Bernard Barbarin and published by Geological Society of America. This book was released on 2001-01-01 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Granitic Systems written by O.T. Ramo and published by Elsevier. This book was released on 2005-05-20 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: This special volume stems from a symposium 'Granitic Systems - State of the Art and Future Avenues' that was held at the Department of Geology, University of Helsinki to mark the retirement of Professor Ilmari Haapala. The twenty articles in the volume cover a wide range of granite-related topics and focus on three general themes: tectonics and source regions, petrologic processes, and fractionated granites and pegmatites. Both original papers and reviews are included, and the volume will be acknowledged by anyone with a background in Earth Sciences ad a flavor for granitoid rocks. * Comprehensive account of the current status of granite-oriented research * Topics ranging from mineralogy, petrology, and geochemistry to tectonics and crustal evolution

Download or read book The Second Hutton Symposium on the Origin of Granites and Related Rocks written by P. E. Brown and published by Geological Society of America. This book was released on 1992-01-01 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Transscandinavian Igneous Belt TIB in Sweden written by Karin Högdahl and published by . This book was released on 2004 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geochemistry written by William M. White and published by John Wiley & Sons. This book was released on 2013-01-22 with total page 1218 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive introduction to the field of geochemistry. The book first lays out the ‘geochemical toolbox’: the basic principles and techniques of modern geochemistry, beginning with a review of thermodynamics and kinetics as they apply to the Earth and its environs. These basic concepts are then applied to understanding processes in aqueous systems and the behavior of trace elements in magmatic systems. Subsequent chapters introduce radiogenic and stable isotope geochemistry and illustrate their application to such diverse topics as determining geologic time, ancient climates, and the diets of prehistoric peoples. The focus then broadens to the formation of the solar system, the Earth, and the elements themselves. Then the composition of the Earth itself becomes the topic, examining the composition of the core, the mantle, and the crust and exploring how this structure originated. A final chapter covers organic chemistry, including the origin of fossil fuels and the carbon cycle’s role in controlling Earth’s climate, both in the geologic past and the rapidly changing present. Geochemistry is essential reading for all earth science students, as well as for researchers and applied scientists who require an introduction to the essential theory of geochemistry, and a survey of its applications in the earth and environmental sciences. Additional resources can be found at: www.wiley.com/go/white/geochemistry

Download or read book Trace Element Geochemistry of Oceanic Peridotites and Silicate Melt Inclusions written by Kevin Todd Michael Johnson and published by . This book was released on 1990 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mantle melting process is fundamental to basalt genesis and crustal accretion at mid-ocean ridges. It is believed that melts ascend more rapidly than the surrounding mantle, implying a process similar to fractional melting may be occurring, but geochemical evidence for this has been lacking. Furthermore, crustal accretion is thought to be episodic at slow spreading ridges, but sampling programs that can test this temporal variability are virtually nonexistent. This dissertation examines the trace element compositions of abyssal peridotites and discusses how they preserve details of the melting process that are not recognizable in mid-ocean ridge basalts. The results support fractional melting as the dominant melting process in the sub-ridge upper mantle. Evidence is also presented supporting non-steady state mantle melting at the Atlantis II Fracture Zone cutting the very slow spreading Southwest Indian Ridge. Trace element compositions of peridotite clinopyroxenes from fracture zones along the American-Antarctic and Southwest Indian Ridges vary as a function of proximity to hotspots. The results presented in Chapter 2 are consistent with higher degrees of melting and greater incompatible element depletion in the upper mantle near hotspots. All peridotites studied are consistent with being residues of fractional melting and inconsistent with batch melting. Some samples recovered near hotspots appear to have begun melting in the garnet stability field, deeper than samples recovered away from hotspots. Most samples show pronounced negative Zr and Ti anomalies, which increase with increasing incompatible element depletion (increased melting), on extended rare earth (spider) diagrams. The results of Chapter 2 indicated the importance of accurately knowing trace element partition coefficients between clinopyroxene and liquid. It was found that existing partitioning studies report either rare earth elements, Ti, or Zr, but not all elements together. Thus, there is ambiguity about relative partition coefficients for these elements. Accurate knowledge of partitioning is important in understanding the formation of negative Zr and Ti anomalies observed in peridotite clinopyroxenes as well as in constructing realistic melting models for peridotites. To that end, Chapter 3 reports the results of a clinopyroxene/basaltic liquid trace element partitioning study carried out on natural dredged basalts and experimental charges of mid-ocean ridge basalts. It was found that there are small negative anomalies in the partiton coefficients of Zr and Ti relative to adjacently plotted rare earth elements on spider diagrams. Fractional melting implies that small parcels of refractory (e.g., high Mg/[Mg+Fe]), incompatible element depleted melts must exist somewhere in the ascending body of melt. Since mixing, wall rock reaction, and fractional crystallization probably alter the compositions of silicate melts extensively on their way from source to surface, representatives of these refractory fractional melts will rarely be erupted as flows on the seafloor. However, some refractory silicate melt inclusions possess compositional characteristics akin to those expected in fractional melts, i.e. low incompatible element concentrations and fractionated trace element ratios. Chapter 4 is a study of refractory melt inclusions from a variety of tectonic settings. The inclusions were obtained from Dr. A.V. Sobolev of the Vernadsky Institute of Geochemistry, Soviet Academy of Sciences, Moscow. They are not ideally suited for studying mid-ocean ridge processes, as only a few of the inclusions are from this environment, but in general, the inclusions show more refractory, incompatible element depleted compositions than their host lavas. Furthermore, the suite of inclusions in different mineral phases contained in a single N-type mid-ocean ridge basalt show variable trace element characteristics indicating unrelated sources for some inclusions. The results of the study do not strongly endorse the fractional melting hypothesis, but some support is suggested by trace element depletions and fractionations warranting a more thorough study of a suite of inclusions. Finally, the along-ridge major and trace element variability in peridotites observed previously and in Chapter 2 is compared to the variability found in a single fracture zone. The high sampling density at the Atlantis IT Fracture Zone on the Southwest Indian Ridge, coupled with its great distance from a hotspot make it a good subject for a baseline study. It was found that the compositional variability observed in peridotites from the Atlantis II Fracture Zone covers nearly the whole range of compositions found along the AmericanAntarctic and Southwest Indian Ridges in Chapter 2. However, there are systematics to this wide range, suggesting different processes may control the depletions. On the eastern side of the transform, a compositional gradient is observed from the center of the eastern wall to the northern ridge-transform intersection. Peridotites on this side have become gradually more depleted in incompatible elements and modal clinopyroxene over at least the last 10-11 million years. Samples from the western side of the transform are, in general, more depleted than those from the eastern side and show some indication of a compositional gradient as well, although sampling is less dense. Basalts from the western side are clearly different in iron composition and degree of rare earth element fractionation. These differences are consistent with higher pressure, higher degrees of melting producing lavas on the western side. It is believed that the long wavelength chemical variations corresponding to hotspot proximity described in Chapter 2 result from regional thermal conditions in the upper mantle imposed, in large part, by the hotspots. On the other hand, the short wavelength variability on a fracture zone or spreading cell scale may result from episodic mantle upwelling and magma production due to non-steady state accretion at very slow spreading ridges.

Download or read book Metasomatism and the Chemical Transformation of Rock written by Daniel Harlov and published by Springer Science & Business Media. This book was released on 2012-08-14 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid-aided mass transfer and subsequent mineral re-equilibration are the two defining features of metasomatism and must be present in order for metamorphism to occur. Coupled with igneous and tectonic processes, metasomatism has played a major role in the formation of the Earth’s continental and oceanic crust and lithospheric mantle as well as in their evolution and subsequent stabilization. Metasomatic processes can include ore mineralization, metasomatically induced alteration of oceanic lithosphere, mass transport in and alteration of subducted oceanic crust and overlying mantle wedge, which has subsequent implications regarding mass transport, fluid flow, and volatile storage in the lithospheric mantle overall, as well as both regional and localized crustal metamorphism. Metasomatic alteration of accessory minerals such as zircon or monazite can allow for the dating of metasomatic events as well as give additional information regarding the chemistry of the fluids responsible. Lastly present day movement of fluids in both the lithospheric mantle and deep to mid crust can be observed utilizing geophysical resources such as electrical resistivity and seismic data. Such observations help to further clarify the picture of actual metasomatic processes as inferred from basic petrographic, mineralogical, and geochemical data. The goal of this volume is to bring together a diverse group of geologists, each of whose specialities and long range experience regarding one or more aspects of metasomatism during geologic processes, should allow them to contribute to a series of review chapters, which outline the basis of our current understanding of how metasomatism influences and helps to control both the evolution and stability of the crust and lithospheric mantle.