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  • 1
    Monograph available for loan
    Monograph available for loan
    Chantilly, Va. : Mineralogical Society of America
    Associated volumes
    Call number: 11/M 07.0429
    In: Reviews in mineralogy & geochemistry
    Description / Table of Contents: The idea for this book was conceived in early June, 2005 at a paleoaltimetry workshop held at Lehigh University, Lehigh, Pennsyalvania and organized by Dork Sahagian. The workshop was funded by the tectonics program at NSF, and was designed to bring together researchers in paleoaltimetry to discuss different techniques and focus the community on ways of improving paleoelevation estimates and consequent interpretations of geodynamics and tectonics. At this meeting, some commented that a comprehensive volume describing the different methods could help advance the field. I offered to contact the Mineralogical Society of America and the Geochemical Society about publishing a RiMG volume on paleoaltimetry. Because many of the techniques used to infer paleoelevations are geochemically-based or deal with thermodynamic principles, the GS and MSA agreed to the project. Two years and roughly 1000 e-mails later, our book has arrived. The book is organized into 4 sections: Geodynamic and geomorphologic rationale (Clark). This chapter provides the broad rationale behind paleoaltimetry, i.e., why we study it. Stable isotope proxies. These 4 chapters cover theory of stable isotopes in precipitation and their response to altitudinal gradients (Rowley), and stable isotopes sytematics in paleosols (Quade, Garzione and Eiler), silicates (Mulch and Chamberlain) and fossils (Kohn and Dettman). Proxies of atmospheric properties. These 4 chapters cover temperature lapse rates (Meyer), entropy (Forest), and atmospheric pressure proxies, including total atmospheric pressure from gas bubbles in basalt (Sahagian and Proussevitch), and the partial pressure of CO2 (Kouwenberg, Kürshner, and McElwain). Note that clumped isotope thermometry (Quade, Garzione and Eiler) also provides direct estimates of temperature. Radiogenic and cosmogenic nuclides. These 2 chapters cover low-temperature thermochronologic approaches (Reiners) and cosmogenic isotopes (Riihimaki and Libarkin). Some chapters overlap in general content (e.g., basic principles of stable isotopes in precipitation are covered to different degrees in all stable isotope chapters), but no attempt was made to limit authors' discussion of principles, or somehow attempt to arrive at a "consensus view" on any specific topic. Because science advances by critical discussion of concepts, such restrictions were viewed as counterproductive. This does mean that different chapters may present different views on reliability of paleoelevation estimates, and readers are advised to read other chapters in the book on related topics – they may be more closely linked than they might at first appear! I hope readers of this book will discover and appreciate the synergy among paleoaltimetry, climate change, and tectonic geomorphology. These interrelationships create a complex, yet rich field of scientific enquiry that in turn offers insights into climate and geodynamics.
    Type of Medium: Monograph available for loan
    Pages: X, 278 S. , graph. Darst.
    ISBN: 0-939950-78-2 , 978-0-939950-78-2
    ISSN: 1529-6466
    Series Statement: Reviews in mineralogy & geochemistry 66
    Classification:
    Geochemistry
    Note: Chapter 1. The Significance of Paleotopography by Marin K. Clark, p. 1 - 22 Chapter 2. Stable Isotope-Based Paleoaltimetry: Theory and Validation by David B. Rowley, p. 23 - 52 Chapter 3. Paleoelevation Reconstruction Using Pedogenic Carbonates by Jay Quade, Carmala Garzione, and John Eiler, p. 53 - 88 Chapter 4. Stable Isotope Paleoaltimetry in Orogenic Belts – The Silicate Record in Surface and Crustal Geological Archives by Andreas Mulch and C. Page Chamberlain, p. 89 - 118 Chapter 5. Paleoaltimetry from Stable Isotope Compositions of Fossils by Matthew J. Kohn and David L. Dettman, p. 119 - 154 Chapter 6. A Review of Paleotemperature–Lapse Rate Methods for Estimating Paleoelevation from Fossil Floras by Herbert W. Meyer, p. 155 - 172 Chapter 7. Paleoaltimetry: A Review of Thermodynamic Methods by Chris E. Forest, p. 173 - 194 Chapter 8. Paleoelevation Measurement on the Basis of Vesicular Basalts by Dork Sahagian and Alex Proussevitch, p. 195 - 214 Chapter 9. Stomatal Frequency Change Over Altitudinal Gradients: Prospects for Paleoaltimetry by Lenny L. R. Kouwenberg, Wolfram M. Kürschner, and Jennifer C. McElwain, p. 215 - 242 Chapter 10. Thermochronologic Approaches to Paleotopography by Peter W. Reiners, p. 243 - 268 Chapter 11. Terrestrial Cosmogenic Nuclides as Paleoaltimetric Proxies by Catherine A. Riihimaki and Julie C. Libarkin, p. 269 - 278
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  • 2
    Monograph available for loan
    Monograph available for loan
    Washington, D.C. : Mineralogical Society of America
    Associated volumes
    Call number: 11/M 03.0010
    In: Reviews in mineralogy & geochemistry
    Description / Table of Contents: Several years ago, John Rakovan and John Hughes (colleagues at Miami of Ohio), and later Matt Kohn (at South Carolina), separately proposed short courses on phosphate minerals to the Council of the Mineralogical Society of America (MSA). Council suggested that they join forces. Thus this volume, Phosphates: Geochemical, Geobiological, and Materials Importance, was organized. It was prepared in advance of a short course of the same title, sponsored by MSA and presented at Golden, Colorado, October 25-27. We are pleased to present this volume entitled Phosphates: Geochemical, Geobiological and Materials Importance. Phosphate minerals are an integral component of geological and biological systems. They are found in virtually all rocks, are the major structural component of vertebrates, and when dissolved are critical for biological activity. This volume represents the work of many authors whose research illustrates how the unique chemical and physical behavior of phosphate minerals permits a wide range of applications that encompasses phosphate mineralogy, petrology, biomineralization, geochronology, and materials science. While diverse, these fields are all linked structurally, crystal-chemically and geochemically. As geoscientists turn their attention to the intersection of the biological, geological, and material science realms, there is no group of compounds more germane than the phosphates. The chapters of this book are grouped into five topics: Mineralogy and Crystal Chemistry, Petrology, Biomineralization, Geochronology, and Materials Applications. In the first section, three chapters are devoted to mineralogical aspects of apatite, a phase with both inorganic and organic origins, the most abundant phosphate mineral on earth, and the main mineral phase in the human body. Monazite and xenotime are highlighted in a fourth chapter, which includes their potential use as solid-state radioactive waste repositories. The Mineralogy and Crystal Chemistry section concludes with a detailed examination of the crystal chemistry of 244 other naturally-occurring phosphate phases and a listing of an additional 126 minerals. In the Petrology section, three chapters detail the igneous, metamorphic, and sedimentary aspects of phosphate minerals. A fourth chapter provides a close look at analyzing phosphates for major, minor, and trace elements using the electron microprobe. A final chapter treats the global geochemical cycling of phosphate, a topic of intense, current geochemical interest. The Biomineralization section begins with a summary of the current state of research on bone, dentin and enamel phosphates, a topic that crosses disciplines that include mineralogical, medical, and dental research. The following two chapters treat the stable isotope and trace element compositions of modern and fossil biogenic phosphates, with applications to paleontology, paleoclimatology, and paleoecology. The Geochronology section focuses principally on apatite and monazite for U-ThPb, (U- Th)/He, and fission-track age determinations; it covers both classical geochronologic techniques as well as recent developments. The final section-Materials Applications-highlights how phosphate phases play key roles in fields such as optics, luminescence, medical engineering and prosthetics, and engineering of radionuclide repositories. These chapters provide a glimpse of the use of natural phases in engineering and biomedical applications and illustrate fruitful areas of future research in geochemical, geobiological and materials science. We hope all chapters in this volume encourage researchers to expand their work on all aspects of natural and synthetic phosphate compounds.
    Type of Medium: Monograph available for loan
    Pages: xv, 742 S.
    ISBN: 0-939950-60-X , 978-0-939950-60-7
    ISSN: 1529-6466
    Series Statement: Reviews in mineralogy & geochemistry 48
    Classification:
    Geochemistry
    Language: English
    Note: Chapter 1. The Crystal Structure of Apatite, Ca5(PO4)3(F,OH,Cl) by John M. Hughes and John Rakovan, p. 1 - 12 Chapter 2. Compositions of the Apatite-Group Minerals: Substitution Mechanisms and Controlling Factors by Yuanming Pana and Michael E. Fleet, p. 13 - 50 Chapter 3. Growth and Surface Properties of Apatite by John Rakovan, p. 51 - 86 Chapter 4. Synthesis, Structure and Properties of Monazite, Pretulite, and Xenotime by Lynn A. Boatner, p. 87 - 122 Chapter 5. The Crystal Chemistry of the Phosphate Minerals by Danielle M.C. Huminicki and Frank C. Hawthorne, p. 123 - 254 Chapter 6. Apatite in Igneous Systems by Philip M. Piccoli and Philip A. Candela, p. 255 - 292 Chapter 7. Apatite, Monazite, and Xenotine in Metamorphic Rocks by Frank S. Spear and Joseph M. Pyle, p. 293 - 336 Chapter 8. Electron Microprobe Analysis of REE in Apatite, Monazite and Xenotime: Protocols and Pitfalls by Joseph M. Pyle, Frank S. Spear, and David A. Wark, p. 337 - 362 Chapter 9. Sedimentary Phosphorites - An Example: Phosphoria Formation, Southeastern Idaho, U.S.A by Andrew C. Knudsen and Mickey E. Gunter, p. 363 - 390 Chapter 10. The Global Phosphorus Cycle by Gabriel M. Filippelli, p. 391 - 426 Chapter 11. Calcium Phosphate Biominerals by James C. Elliott, p. 427 - 454 Chapter 12. Stable Isotope Composition of Biological Apatite by Matthew J. Kohn and Thure E. Cerling, p. 455 - 488 Chapter 13. Trace Elements in Recent and Fossil Bone Apatite by Clive N. Trueman and Noreen Tuross, p. 489 - 522 Chapter 14. U-TH-Pb Dating of Phosphate Minerals by T. Mark Harrison, Elizabeth J. Catlos, and Jean-Marc Montel, p. 523 - 558 Chapter 15. (U-Th)/He Dating of Phosphates: Apatite, Monazite, and Xenotime by Kenneth A. Farley and Daniel F. Stockli, p. 559 - 578 Chapter 16. Fission Track Dating of Phosphate Minerals and the Thermochronology of Apatite by Andrew J.W. Gleadow, David X. Belton, Barry P. Kohn, and Roderick W. Brown, p. 579 - 630 Chapter 17. Biomedical Application of Apatites by Karlis A. Gross and Christopher C. Berndt, p. 631 - 672 Chapter 18. Phosphates as Nuclear Waste Forms by Rodney C. Ewing and LuMin Wang, p. 673 - 700 Chapter 19. Apatite Luminescence by Glenn A. Waychuna, p. 701 - 742
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  • 3
    Description / Table of Contents: The idea for this book was conceived in early June, 2005 at a paleoaltimetry workshop held at Lehigh University, Lehigh, Pennsyalvania and organized by Dork Sahagian. The workshop was funded by the tectonics program at NSF, and was designed to bring together researchers in paleoaltimetry to discuss different techniques and focus the community on ways of improving paleoelevation estimates and consequent interpretations of geodynamics and tectonics. At this meeting, some commented that a comprehensive volume describing the different methods could help advance the field. I offered to contact the Mineralogical Society of America and the Geochemical Society about publishing a RiMG volume on paleoaltimetry. Because many of the techniques used to infer paleoelevations are geochemically-based or deal with thermodynamic principles, the GS and MSA agreed to the project. Two years and roughly 1000 e-mails later, our book has arrived. The book is organized into 4 sections: (1) Geodynamic and geomorphologic rationale (Clark). This chapter provides the broad rationale behind paleoaltimetry, i.e., why we study it. (2) Stable isotope proxies. These 4 chapters cover theory of stable isotopes in precipitation and their response to altitudinal gradients (Rowley), and stable isotopes sytematics in paleosols (Quade, Garzione and Eiler), silicates (Mulch and Chamberlain) and fossils (Kohn and Dettman). (3) Proxies of atmospheric properties. These 4 chapters cover temperature lapse rates (Meyer), entropy (Forest), and atmospheric pressure proxies, including total atmospheric pressure from gas bubbles in basalt (Sahagian and Proussevitch), and the partial pressure of CO2 (Kouwenberg, Kürshner, and McElwain). Note that clumped isotope thermometry (Quade, Garzione and Eiler) also provides direct estimates of temperature. (4) Radiogenic and cosmogenic nuclides. These 2 chapters cover low-temperature thermochronologic approaches (Reiners) and cosmogenic isotopes (Riihimaki and Libarkin). Some chapters overlap in general content (e.g., basic principles of stable isotopes in precipitation are covered to different degrees in all stable isotope chapters), but no attempt was made to limit authors' discussion of principles, or somehow attempt to arrive at a "consensus view" on any specific topic. Because science advances by critical discussion of concepts, such restrictions were viewed as counterproductive. This does mean that different chapters may present different views on reliability of paleoelevation estimates, and readers are advised to read other chapters in the book on related topics – they may be more closely linked than they might at first appear! I hope readers of this book will discover and appreciate the synergy among paleoaltimetry, climate change, and tectonic geomorphology. These interrelationships create a complex, yet rich field of scientific enquiry that in turn offers insights into climate and geodynamics.
    Pages: Online-Ressource (X, 278 Seiten)
    ISBN: 0939950782
    Language: English
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  • 4
    Description / Table of Contents: Chapter 1. Significant ages—An introduction to petrochronology by Martin Engi, Pierre Lanari, Matthew J. Kohn, p. 1-12 --- Chapter 2. Phase relations, reaction sequences and petrochronology by Chris Yakymchuk, Chris Clark, Richard W. White, p. 13-54 --- Chapter 3. Local bulk composition effects on metamorphic mineral assemblages by Pierre Lanari and Martin Engi, p. 55-102 --- Chapter 4. Diffusion: Obstacles and opportunities in petrochronology by Matthew J. Kohn and Sarah c. Penniston–Dorland, p. 103-152 --- Chapter 5. Electron microprobe petrochronology by Michael L. Williams, Michael J. Jercinovic, Kevin H. Mahan, and Gregory Dumond, p. 153-182 --- Chapter 6. Petrochronology by laser–ablation inductively coupled plasma mass spectrometry by Andrew R. C. Kylander–Clark, p. 183-198 --- Chapter 7. Secondary ionization mass spectrometry analysis in petrochronology by Axel K. Schmitt and Jorge A. Vazquez, p. 199-230 --- Chapter 8. Petrochronology and TIMS by Blair Schoene and Ethan F. Baxter, p. 231-260 --- Chapter 9. Zircon: The metamorphic mineral by Daniela Rubatto, p. 261-296 --- Chapter 10. Petrochronology of zircon and baddeleyite in igneous rocks: Reconstructing magmatic processes at high temporal resolution by Urs Schaltegger and Jishua H. F. L. Davies, p. 297-328 --- Chapter 11. Hadean zircon petrochronology by T. Mark Harrison, Elizabeth A. Bell, and Patrick Boehnke, p. 329-364 --- Chapter 12. Petrochronology based on REE–minerals: monazite, allanite, xenotime, apatite by Martin Engi, p. 365-418 --- Chapter 13. Titanite petrochronology by Matthew J. Kohn, p. 419-442 --- Chapter 14. Petrology and geochronology of rutile by Thomas Zack and Ellen Kooijman, p. 443-468 --- Chapter 15. Garnet: A rock-forminf mineral petrochronometer by E. F. Baxter, M. J. Caddick, p. 469-534 --- Chapter 16. Chronometry and speedometry of magmatic processes using chemical diffusion in olivine, plagioclase and pyroxenes by Ralf Dohmen, Kathrin Faak, and Jon D. Blundy, p. 535-575
    Pages: Online-Ressource (XIV, 575 Seiten)
    ISBN: 9780939950058
    Language: English
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  • 5
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Eocene–Oligocene transition towards a cool climate (∼33.5 million years ago) was one of the most pronounced climate events during the Cenozoic era. The marine record of this transition has been extensively studied. However, significantly less research has focused on ...
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 113 (1993), S. 24-39 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A combined analytical and numerical evaluation of the uncertainties in P-T paths is made for three assemblages that propagates errors in the parameters: initial pressure, initial temperature, initial composition, change of composition of monitor parameters, endmember entropy, and endmember volume. Propagated errors along an isobaric heating path (ΔT=77°C) for assemblage 1 (Grt-Bt-Pl-Qtz-Ms-Chl-H2O), using as monitor parameters the mole fractions of almandine, spessartine, grossular, and anorthite, and ignoring uncertainties in thermodynamic properties, are approximately ±320 bars (1σ) and ±8.3°C (1σ) if rim compositional uncertainties of 5% in major cations are assumed, or ±2.5°C (1σ) and ±50 bars (1σ) if electron microprobe analytical uncertainties are assumed for compositions. The largest source of uncertainty is from the errors in the monitor parameters, and P-T path uncertainties can depend critically on which monitor parameters are used. If the mole fraction of annite is used as a monitor parameter in place of the anorthite content of plagioclase, then propagated uncertainties are worse than ±29°C (1σ) and ±5800 bars (1σ). P-T path uncertainties also depend on assemblage. 1σ precisions in assemblages 2 (Grt−Bt−Pl−Qtz−Ms−Sil−H2O) and 3 (Grt−Bt−Qtz−Kfs−Sil−H2O) using as monitor parameters the mole fractions of almandine, spessartine, grossular, and anorthite are calculated to be ±267 bars and ±43.4°C and ±372 bars and ±8.2°C respectively. Estimates of the accuracies in P-T paths that include potential errors in endmember entropy of ±1 J/mol·K and in endmember volume of ±1 cm3/mol are: ±324 bars and ±8.5°C (assemblage 1), ±341 bars and ±48.6°C (assemblage 2), and ±388 bars and ±9.7°C (assemblage 3). Use of different garnet, plagioclase, and muscovite activity models can change the length of a P-T path by as much as 15%, but does not typically change directions in P-T space significantly. Models that incorporate changes of fluid composition shorten P-T paths in assemblages 1 and 3 but do not change trajectories significantly. Assemblage 2 is virtually unaffected by fluid phase models. For the mineral assemblages considered here and using appropriate monitor parameters, propagated errors are small compared to the total path length, suggesting that the differential thermodynamic approach is a precise and accurate method for determining amounts of heating or thickening during metamorphism, and hence for interpreting orogenic processes.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 113 (1993), S. 249-261 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A general model has been developed to calculate changes of δ18O of minerals in addition to their composition and modal abundance in metamorphic systems. A complete set of differential equations can be written to describe any chemical system in terms of the variables dP, dT, dX, dM, and dδ18O (X, M, and δ18O refer to the chemical composition, number of moles, and oxygen isotope composition of each phase respectively). This set is composed of the differentials of five subsets of equations: (1) conditions of heterogeneous equilibrium; (2) compositional stoichiometry for each mineral; (3) mass balance for each oxide component; (4) oxygen isotope partitioning between phases; (5) conservation of the oxygen isotope ratio of the system. The variance of the complete set of equations is 2, and changes of δ18O, composition, and modal abundance for each mineral can be calculated for arbitrary changes of P and T. Applications to a typical pelitic bulk composition at amphibolite and lower granulite facies conditions suggest that for systems dominated by continuous reactions such as: (a) chlorite + quartz = garnet+H2O; (b) staurolite + biotite = garnet + muscovite + H2O; or (c) garnet + muscovite = sillimanite + biotite, isopleths of mineral δ18O are nearly independent of pressure, and have a spacing of about 0.1‰ per 10–20°C. For nearly discontinuous reactions such as: (d) garnet + chlorite + muscovite = biotite + staurolite+H2O; (e) staurolite + muscovite = biotite + aluminosilicate + garnet+H2O; or (f) muscovite + quartz = sillimanite + K-feldspar+H2O, isopleths of mineral δ18O have slopes more nearly parallel to endmember reaction boundaries and δ18O of phases can have a greater temperature dependence (e.g., 0.1‰ per 2°C for reaction d). This behavior results from relatively large amounts of reaction progress for small changes of P or T. However, the calculated exhaustion of a reactant within 0.1–5°C ensures that the predicted effects of such reactions on mineral δ18O will not exceed ∼0.25‰ for typical bulk compositions. Models that allow for fractional crystallization of garnet suggest that prograde garnet zoning in pelitic assemblages will be relatively smooth until staurolite becomes unstable. At higher temperatures, garnet may develop a step of as much as 0.6‰ in its core-rim zoning as a result of combined garnet resorption during the continuous reaction garnet + muscovite = sillimanite + biotite and repartitioning of the garnet rim composition to relatively heavy δ18O. The models are insensitive to the degree to which garnet fractionally crystallizes and to the isotope fractionation factors used; only extreme changes in modal abundance or bulk composition for a given mineral assemblage can produce significant changes in the predicted trends. In the absence of infiltration, isotopic shifts resulting from net transfer reactions for minerals in typical amphibolite, eclogite, and lower granulite facies metapelites and metabasites are inferred from the models to be ∼1‰ or less for ∼150°C of heating.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 132 (1998), S. 209-224 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A generalized approach for retrieving equilibrium isotope fractionations from natural rocks is proposed in which models of prograde reaction histories and retrograde diffusional exchange are used to identify coexisting minerals with similar isotope closure temperatures. Examples using literature data and new analyses from 32 natural amphibolite-facies schists demonstrate both the feasibility and limitations of obtaining equilibrium oxygen isotope fractionations from minerals in natural rocks. By screening samples according to the theoretical models, natural data are shown to have highly consistent mineral fractionations (±2σ reproducibilities of ±0.16 to 0.54‰) that within uncertainty reproduce experimental determinations among the minerals quartz, biotite, muscovite, and calcic amphibole. This correspondence indicates that the proposed theoretically-based selection criteria improve the likelihood of measuring equilibrium fractionations. The new data further corroborate the expected progressive enrichment of δ18O in the orthosilicates with increasing Al+Si relative to Fe+Mg: Δ(Ky-Grt) ∼1.05‰, Δ(St-Grt) ∼0.6‰, and Δ(St-Cld) ∼0.3‰ at 525–575 °C. In contrast, typical samples that fail to satisfy screening criteria exhibit fractionations involving quartz, biotite, and amphibole that are strongly disequilibrium because of exchange during cooling. Theoretical screening of samples prior to isotope analysis allows robust, independent assessment of theoretical and experimental determinations of equilibrium isotope fractionations.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 134 (1999), S. 17-32 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A relatively simple petrogenetic grid for partial melting of pelitic rocks in the NCKFMASH system is presented based on the assumption that the only H2O available for melting is through dehydration reactions. The grid includes both discontinuous and continuous Fe-Mg reactions; contours of Fe/(Fe+Mg) for continuous reactions define P-T vectors along which continuous melting will occur. For biotite-bearing assemblages (garnet+biotite + sillimanite + K-feldspar + liquid and garnet + biotite + cordierite + K-feldspar + liquid), Fe/(Fe+Mg) contours have negative slopes and melting will occur with increasing temperature or pressure. For biotite-absent assemblages (garnet + cordierite + sillimanite + K-feldspar + liquid or garnet + cordierite + orthopyroxene + K-feldspar + liquid) Fe/(Fe + Mg) contours have flat slopes and melting will occur only with increasing pressure. The grid predicts that abundant matrix K-feldspar should only be observed if rocks are heated at P 〈 3.8 kbar, that abundant retrograde muscovite should only be observed if rocks are cooled at P 〉 3.8 kbar, and that generation of late biotite + sillimanite replacing garnet, cordierite, or as selvages around leu- cosomes should be common in rocks in which melt is not removed. There is also a predicted field for dehydration melting of staurolite between 5 and 12 kbar. Textures in migmatites from New Hampshire, USA, suggest that prograde dehydration melting reactions are very nearly completely reversible during cooling and crystallization in rocks in which melt is not removed. Therefore, many reaction textures in “low grade” migmatites may represent retrograde rather than prograde reactions.
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  • 10
    Publication Date: 2021-07-05
    Description: We compared stable isotopes of water in plant stem (xylem) water and soil collected over a complete growing season from five well‐known long‐term study sites in northern/cold regions. These spanned a decreasing temperature gradient from Bruntland Burn (Scotland), Dorset (Canadian Shield), Dry Creek (USA), Krycklan (Sweden), to Wolf Creek (northern Canada). Xylem water was isotopically depleted compared to soil waters, most notably for deuterium. The degree to which potential soil water sources could explain the isotopic composition of xylem water was assessed quantitatively using overlapping polygons to enclose respective data sets when plotted in dual isotope space. At most sites isotopes in xylem water from angiosperms showed a strong overlap with soil water; this was not the case for gymnosperms. In most cases, xylem water composition on a given sampling day could be better explained if soil water composition was considered over longer antecedent periods spanning many months. Xylem water at most sites was usually most dissimilar to soil water in drier summer months, although sites differed in the sequence of change. Open questions remain on why a significant proportion of isotopically depleted water in plant xylem cannot be explained by soil water sources, particularly for gymnosperms. It is recommended that future research focuses on the potential for fractionation to affect water uptake at the soil‐root interface, both through effects of exchange between the vapour and liquid phases of soil water and the effects of mycorrhizal interactions. Additionally, in cold regions, evaporation and diffusion of xylem water in winter may be an important process.
    Description: We compared stable isotopes of water in plant stem (xylem) water and soil collected over a complete growing season from five well‐known long‐term study sites in northern/cold regions. Xylem water was isotopically depleted compared to soil waters, most notably for deuterium. At all sites except one, water sources of angiosperms could be associated with soil water, while the sources of water uptake by gymnosperms were much less easily explained.
    Description: FP7 Ideas: European Research Council http://dx.doi.org/10.13039/100011199
    Description: KAW Branch‐Point project
    Description: SITES (VR)
    Description: Boise State University http://dx.doi.org/10.13039/100007233
    Description: US National Science Foundation
    Description: Leverhulme Trust through the ISO‐LAND project
    Keywords: 551.9 ; cold regions ; critical zone ; northern environments ; stable isotopes ; soil isotopes ; xylem isotopes
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