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1. Local order of orthorhombic weberite-type Y3TaO7 as determined by neutron total scattering and density functional theory calculations✰

Author: Jörg Neuefeind, Maik Lang, Igor M. Gussev, Rodney C. Ewing, Fuxiang Zhang, Eric C. O'Quinn, Gianguido Baldinozzi, The University of Tennessee [Knoxville], Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, and Stanford University-Stanford University
Subjects: Materials science, Polymers and Plastics, Neutron diffraction, Pair distribution function analysis, 02 engineering and technology, 01 natural sciences, Molecular physics, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, Neutron, Rare-earth, 010302 applied physics, Scattering, Metals and Alloys, Pair distribution function, Space group, [CHIM.MATE]Chemical Sciences/Material chemistry, Crystalline oxides, 021001 nanoscience & nanotechnology, Electronic, Optical and Magnetic Materials, Density functional theory, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Ceramics and Composites, Orthorhombic crystal system, [PHYS.COND.CM-SCE]Physics [physics]/Condensed Matter [cond-mat]/Strongly Correlated Electrons [cond-mat.str-el], 0210 nano-technology, Stoichiometry
Abstract: International audience; Weberite-type oxides are a family of oxides with A3BO7 stoichiometry that can adopt different space groups depending on chemical composition. There is a discrepancy in previous studies as to whether Y3TaO7 is the orthorhombic C2221 or the Ccmm space group. Here, we describe the short- and long-range structural properties of weberite-type Y3TaO7 using neutron total scattering data, which has a high sensitivity to the oxygen sublattice. Simultaneous analysis of both short- and long-range structural data via conventional Rietveld and small box modelling demonstrates that Y3TaO7 is best modeled as C2221. While the Ccmm describes equally well the long-range structure, pair distribution function analysis revealed that the local atomic configuration can be best modelled as C2221. This is corroborated by first-principles calculations that confirm the energetic preference of the C2221 over Ccmm. Neutron total scattering data are reported for the first time for the Y3TaO7 weberite-type ceramics.
Published: 2020
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2. Decreasing Phanerozoic extinction intensity as a consequence of Earth surface oxygenation and metazoan ecophysiology

Author: Erik A. Sperling, Richard G. Stockey, Andy Ridgwell, Alexandre Pohl, Seth Finnegan, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), University of California [Riverside] (UC Riverside), University of California (UC), Department of Integrative Biology [Berkeley] (IB), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), European Project: 838373,BioSIGNAL, Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), University of California [Riverside] (UCR), University of California, University of California [Berkeley], University of California-University of California, Pohl, Alexandre, Marie Sklodowska-Curie grant agreement No. 838373 - BioSIGNAL - 838373 - INCOMING, and Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement
Subjects: [SDE] Environmental Sciences, Aquatic Organisms, Hot Temperature, 010504 meteorology & atmospheric sciences, Paleozoic, Earth system evolution, ecophysiology, Earth, Planet, Climate, Oceans and Seas, Effects of global warming on oceans, Biodiversity, Extinction, Biological, Atmospheric sciences, 01 natural sciences, Carbon Cycle, temperature-dependent hypoxia, 03 medical and health sciences, Phanerozoic, Animals, Seawater, Background extinction rate, 14. Life underwater, Ecosystem, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, 0105 earth and related environmental sciences, Extinction event, 0303 health sciences, Multidisciplinary, Extinction, extinction, Atmosphere, Fossils, Hypoxia (environmental), Earth, 15. Life on land, Biological, Biological Evolution, Oxygen, 13. Climate action, Physical Sciences, [SDE]Environmental Sciences, Environmental science, Planet, geographic locations
Abstract: The decline in background extinction rates of marine animals through geologic time is an established but unexplained feature of the Phanerozoic fossil record. There is also growing consensus that the ocean and atmosphere did not become oxygenated to near-modern levels until the mid-Paleozoic, coinciding with the onset of generally lower extinction rates. Physiological theory provides us with a possible causal link between these two observations-predicting that the synergistic impacts of oxygen and temperature on aerobic respiration would have made marine animals more vulnerable to ocean warming events during periods of limited surface oxygenation. Here, we evaluate the hypothesis that changes in surface oxygenation exerted a first-order control on extinction rates through the Phanerozoic using a combined Earth system and ecophysiological modeling approach. We find that although continental configuration, the efficiency of the biological carbon pump in the ocean, and initial climate state all impact the magnitude of modeled biodiversity loss across simulated warming events, atmospheric oxygen is the dominant predictor of extinction vulnerability, with metabolic habitat viability and global ecophysiotype extinction exhibiting inflection points around 40% of present atmospheric oxygen. Given this is the broad upper limit for estimates of early Paleozoic oxygen levels, our results are consistent with the relative frequency of high-magnitude extinction events (particularly those not included in the canonical big five mass extinctions) early in the Phanerozoic being a direct consequence of limited early Paleozoic oxygenation and temperature-dependent hypoxia responses.
Published: 2021

3. Role of Water and Hydroxyl Groups in the Structures of Stetindite and Coffinite, MSiO4 (M = Ce, U)

Author: Thomas Barral, Adel Mesbah, Rodney C. Ewing, Jianming Bai, Vitaliy G. Goncharov, Xiaofeng Guo, Nicolas Clavier, Nicolas Dacheux, Jason Baker, Stéphanie Szenknect, Hongwu Xu, Andrew C. Strzelecki, Paul Estevenon, Artaches Migdisov, Washington State University (WSU), Interfaces de Matériaux en Evolution (LIME), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Earth and Environmental Sciences Division [Los Alamos], Los Alamos National Laboratory (LANL), Brookhaven National Laboratory [Upton, NY] (BNL), UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY)-U.S. Department of Energy [Washington] (DOE), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), and State University of New York (SUNY)-State University of New York (SUNY)
Subjects: actinide geochemistry, Analytical chemistry, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Thermal expansion, Hydrothermal circulation, hydroxylation, Inorganic Chemistry, Metal, chemistry.chemical_compound, Orthosilicate, high temperature structure, confined water, Coffinite, Physical and Theoretical Chemistry, Fourier transform infrared spectroscopy, thermal expansion, coefficients of thermal expansion (CTE), 021001 nanoscience & nanotechnology, Enthalpy of mixing, 0104 chemical sciences, chemistry, visual_art, visual_art.visual_art_medium, 0210 nano-technology, [CHIM.RADIO]Chemical Sciences/Radiochemistry, Solid solution
Abstract: International audience; Orthosilicates adopt the zircon structure-types (I41/amd), consisting of isolated SiO4 tetrahedra joined by A-site metal cations, such as Ce and U. They are of significant interest in the fields of geochemistry, mineralogy, nuclear waste form development and material science. Stetindite (CeSiO4) and coffinite (USiO4) can be formed under hydrothermal conditions despite both being thermodynamically metastable. Water has been hypothesized to play a significant role in stabilizing and forming these orthosilicate phases, though little experimental evidence exists. To understand the effects of hydration or hydroxylation on these orthosilicates, in situ high temperature synchrotron and laboratory-based X-ray diffraction was conducted from 25 °C to ~850 °C. Stetindite maintains its I41/amd symmetry with increasing temperature but exhibits a discontinuous expansion along the a-axis during heating, presumably due to the removal of water confined in the [001] channels, which shrink against thermal expansion along the a-axis. Additional in situ high temperature Raman and FTIR spectroscopy also confirmed the presence of the confined water. Coffinite was also found to expand nonlinearly up to 600 °C, and then thermally decompose into a mixture of UO2 and SiO2. A combination of dehydration and dehydroxylation is proposed for explaining the thermal behavior of coffinite synthesized hydrothermally. Additionally, we investigated high temperature structures of two coffinite-thorite solid solutions, uranothorite (UxTh1-xSiO4), which displayed complex variations in composition during heating that was attributed to the negative enthalpy of mixing. Lastly, for the first time, the coefficients of thermal expansion of CeSiO4, USiO4, U0.46Th0.54SiO4, and U0.9Th0.1SiO4 were determined to be αV = 4.21 × 10-6 °C-1 , 14.29 × 10-6 °C-1 , 17.21 × 10-6 °C-1 , and 17.23 × 10-6 °C-1 , respectively.
Published: 2021
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4. Thermodynamics of CeSiO 4 : Implications for Actinide Orthosilicates

Author: Adel Mesbah, Andrew C. Strzelecki, Clement Bourgeois, Xiaofeng Guo, Paul Estevenon, Nicolas Dacheux, Kyle W. Kriegsman, Stéphanie Szenknect, Rodney C. Ewing, Nian Wei, Di Wu, Washington State University (WSU), Interfaces de Matériaux en Evolution (LIME), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010405 organic chemistry, Neptunium, Thorium, chemistry.chemical_element, Actinide, 010402 general chemistry, 01 natural sciences, Standard enthalpy of formation, 0104 chemical sciences, Plutonium, Inorganic Chemistry, chemistry.chemical_compound, Cerium, chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, Physical chemistry, [CHIM]Chemical Sciences, Orthosilicate, Physical and Theoretical Chemistry, [CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS, Zircon
Abstract: Zircon (ZrSiO4, I41/amd) can accommodate actinides, such as thorium, uranium, and plutonium. The zircon structure has been determined for several of the end-member compositions of other actinides, such as plutonium and neptunium. However, the thermodynamic properties of these actinide zircon structure types are largely unknown due to the difficulties in synthesizing these materials and handling transuranium actinides. Thus, we have completed a thermodynamic study of cerium orthosilicate, stetindite (CeSiO4), a surrogate of PuSiO4. For the first time, the standard enthalpy of formation of CeSiO4 was obtained by high temperature oxide melt solution calorimetry to be -1971.9 ± 3.6 kJ/mol. Stetindite is energetically metastable with respect to CeO2 and SiO2 by 27.5 ± 3.1 kJ/mol. The metastability explains the rarity of the natural occurrence of stetindite and the difficulty of its synthesis. Applying the obtained enthalpy of formation of CeSiO4 from this work, along with those previously reported for USiO4 and ThSiO4, we developed an empirical energetic relation for actinide orthosilicates. The predicted enthalpies of formation of AnSiO4 are then determined with a discussion of future strategies for efficiently immobilizing Pu or minor actinides in the zircon structure.
Published: 2020
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5. Predicting short-range order and correlated phenomena in disordered crystalline materials

Author: Gianguido Baldinozzi, Antonio F. Fuentes, Maik Lang, Eric C. O'Quinn, Kurt E. Sickafus, Matthew G. Tucker, Devon L. Drey, Rodney C. Ewing, Joerg C. Neuefeind, Materials Science and Engineering [University of Tennessee], The University of Tennessee [Knoxville], Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), and Institut de Chimie du CNRS (INC)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Diffraction, Multidisciplinary, Materials science, Scattering, Materials Science, Crystalline materials, SciAdv r-articles, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, Radiation, 021001 nanoscience & nanotechnology, Condensed Matter::Disordered Systems and Neural Networks, 01 natural sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Chemical physics, High pressure, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM.CRIS]Chemical Sciences/Cristallography, Short range order, Neutron, 010306 general physics, 0210 nano-technology, Research Articles, Research Article
Abstract: Short-range structure in disordered materials can be predicted by application of Pauling’s rules., Disordered crystalline materials are used in a wide variety of energy-related technologies. Recent results from neutron total scattering experiments have shown that the atomic arrangements of many disordered crystalline materials are not random nor are they represented by the long-range structure observed from diffraction experiments. Despite the importance of disordered materials and the impact of disorder on the expression of physical properties, the underlying fundamental atomic-scale rules of disordering are not currently well understood. Here, we report that heterogeneous disordering (and associated structural distortions) can be understood by the straightforward application of Pauling’s rules (1929). This insight, corroborated by first principles calculations, can be used to predict the short-range, atomic-scale changes that result from structural disordering induced by extreme conditions associated with energy-related applications, such as high temperature, high pressure, and intense radiation fields.
Published: 2020
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6. Persistence of soil organic carbon caused by functional complexity

Author: Naoise Nunan, Stefano Manzoni, Ingrid Kögel-Knabner, Christina Kaiser, Johannes Lehmann, Markus Reichstein, Kate Maher, William R. Wieder, Margaret S. Torn, Colleen M. Hansel, Joshua P. Schimel, Markus Kleber, University of Vienna [Vienna], Dept Crop & Soil Sci, Oregon State University (OSU), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Politecnico di Milano [Milan] (POLIMI), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Max Planck Society, Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), and Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
Subjects: 2. Zero hunger, chemistry.chemical_classification, Carbon dioxide in Earth's atmosphere, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, chemistry.chemical_element, Soil science, Soil carbon, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Decomposer, Soil management, Climate change mitigation, chemistry, 13. Climate action, [SDE]Environmental Sciences, Soil water, General Earth and Planetary Sciences, Environmental science, Meteorology & Atmospheric Sciences, Organic matter, Carbon, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Soil organic carbon management has the potential to aid climate change mitigation through drawdown of atmospheric carbon dioxide. To be effective, such management must account for processes influencing carbon storage and re-emission at different space and time scales. Achieving this requires a conceptual advance in our understanding to link carbon dynamics from the scales at which processes occur to the scales at which decisions are made. Here, we propose that soil carbon persistence can be understood through the lens of decomposers as a result of functional complexity derived from the interplay between spatial and temporal variation of molecular diversity and composition. For example, co-location alone can determine whether a molecule is decomposed, with rapid changes in moisture leading to transport of organic matter and constraining the fitness of the microbial community, while greater molecular diversity may increase the metabolic demand of, and thus potentially limit, decomposition. This conceptual shift accounts for emergent behaviour of the microbial community and would enable soil carbon changes to be predicted without invoking recalcitrant carbon forms that have not been observed experimentally. Functional complexity as a driver of soil carbon persistence suggests soil management should be based on constant care rather than one-time action to lock away carbon in soils. Dynamic interactions between chemical and biological controls govern the stability of soil organic carbon and drive complex, emergent patterns in soil carbon persistence.
Published: 2020
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7. In situ X-ray diffraction of silicate liquids and glasses under dynamic and static compression to megabar pressures

Author: A. E. Gleason, Eric Galtier, Bob Nagler, R. Bolis, Alessandra Benuzzi-Mounaix, Wendy L. Mao, Siegfried Glenzer, Alessandra Ravasio, A. K. Schuster, Guillaume Fiquet, Gaston Garbarino, Hae Ja Lee, J.-A. Hernandez, Guillaume Morard, M. Guarguaglini, Mohamed Mezouar, Tommaso Vinci, Denis Andrault, Byeongkwan Ko, M. A. Baron, Dimosthenis Sokaras, Roberto Alonso-Mori, Sang Heon Shim, Laboratoire pour l'utilisation des lasers intenses (LULI), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Arizona State University [Tempe] (ASU), Stanford University [Stanford], SLAC National Accelerator Laboratory (SLAC), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), ANR-16-CE31-0008,POMPEI,Propriétés de Mélanges de H2ONH3CH4 d'interet pour les intérieurs planétaires et les exoplanètes.(2016), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), University of Oslo (UiO), Stanford University, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), ANR POMPEI (Grant No. ANR-16-CE31-0008), European Project: 670787,H2020,ERC-2014-ADG,PLANETDIVE(2016), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC)
Subjects: Diffraction, Multidisciplinary, Materials science, 010504 meteorology & atmospheric sciences, [PHYS.PHYS]Physics [physics]/Physics [physics], [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Thermodynamics, Atmospheric temperature range, 01 natural sciences, Silicate, Diamond anvil cell, Mantle (geology), Amorphous solid, chemistry.chemical_compound, chemistry, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], 0103 physical sciences, X-ray crystallography, Core–mantle boundary, Physical Sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: International audience; Properties of liquid silicates under high pressure and high temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core-mantle boundary. Here, we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock compression (up to 130 GPa and 6000 K along the MgSiO3 glass Hugoniot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth's core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely-used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures.
Published: 2020
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8. Controls over δ44/40Ca and Sr/Ca variations in coccoliths: New perspectives from laboratory cultures and cellular models

Author: Luz María Mejía, Ana Kolevica, Anton Eisenhauer, Lorena Abrevaya, Clara T Bolton, Ana Mendez-Vicente, Adina Paytan, Florian Böhm, Heather Stoll, Kirsten Isensee, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Geology Department, and Oviedo University
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Fractionation, 010502 geochemistry & geophysics, 01 natural sciences, Coccolith, Isotopes of calcium, Paleontology, chemistry.chemical_compound, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Gephyrocapsa oceanica, skin and connective tissue diseases, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Emiliania huxleyi, biology, biology.organism_classification, Retention efficiency, Geophysics, chemistry, 13. Climate action, Space and Planetary Science, Environmental chemistry, [SDE]Environmental Sciences, Carbonate, Seawater, sense organs, Geology
Abstract: Coccoliths comprise a major fraction of the global carbonate sink. Therefore, changes in coccolithophores' Ca isotopic fractionation could affect seawater Ca isotopic composition, affecting interpretations of the global Ca cycle and related changes in seawater chemistry and climate. Despite this, a quantitative interpretation of coccolith Ca isotopic fractionation and a clear understanding of the mechanisms driving it are not yet available. Here, we address this gap in knowledge by developing a simple model (CaSri–Co) to track coccolith Ca isotopic fractionation during cellular Ca uptake and allocation to calcification. We then apply it to published and new δ44/40Ca and Sr/Ca data of cultured coccolithophores of the species Emiliania huxleyi and Gephyrocapsa oceanica. We identify changes in calcification rates, Ca retention efficiency and solvation–desolvation rates as major drivers of the Ca isotopic fractionation and Sr/Ca variations observed in cultures. Higher calcification rates, higher Ca retention efficiencies and lower solvation–desolvation rates increase both coccolith Ca isotopic fractionation and Sr/Ca. Coccolith Ca isotopic fractionation is most sensitive to changes in solvation–desolvation rates. Changes in Ca retention efficiency may be a major driver of coccolith Sr/Ca variations in cultures. We suggest that substantial changes in the water structure strength caused by past changes in temperature could have induced significant changes in coccolithophores' Ca isotopic fractionation, potentially having some influence on seawater Ca isotopic composition. We also suggest a potential effect on Ca isotopic fractionation via modification of the solvation environment through cellular exudates, a hypothesis that remains to be tested.
Published: 2018
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9. Effects of Grain Size on the Radiation Response of CeO2, ThO2, and UO2

Author: Cureton, William, Palomares, Raul, Tracy, Cameron, O'Quinn, Eric, Ewing, Rodney C., Baldinozzi, Gianguido, Jie, Lian, Trautmann, Christina, Lang, Maik, Baldinozzi, Gianguido, The University of Tennessee [Knoxville], Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Stanford University, Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Rensselaer Polytechnic Institute (RPI), Helmholtz Centre for Heavy Ion Research (GSI), and Materials Research Society (MRS)
Subjects: [CHIM.MATE] Chemical Sciences/Material chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.CRIS] Chemical Sciences/Cristallography, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract: International audience; Radiation stability is often a key limiting factor in performance of fluorite-structured materials and determining their suitability for use in energy-related applications. In an effort to mitigate the effects of radiation, nanostructured materials are of interest as they incorporate high defect sink strengths [Rose et al., Nanostructured Materials (1995), Nita et al., Journal of Nuclear Materials (2004)]. Recently, it has been shown that the response of CeO2, ThO2, and UO3 to highly ionizing radiation is strongly dependent on the material’s redox response [Tracy et al., Nature Communications (2015)]. When exposed to swift heavy ions, cations in the material are subject to changes in valence which drives swelling and microstrain as irradiation-induced defects accumulate. In this work, we present new insights into how crystallite size affects irradiation-induced redox response and defect accumulation in fluorite-structured simple oxides. Using 946 MeV Au ions at the UNILAC accelerator of the GSI Helmholtz Center, we irradiated microcrystalline and nanocrystalline materials of different compositions containing cations known to reduce (CeO2), remain univalent (ThO2), and oxidize (UO2) under ionizing conditions. Irradiated samples were characterized by synchrotron X-ray diffraction/absorption, neutron total scattering with pair distribution function (PDF) analysis, transmission electron microscopy, and Raman spectroscopy. Each composition exhibits a distinct response between microcrystalline and nanocrystalline forms, such as magnitude of volumetric swelling and secondary phase formation, driven mainly by redox processes. PDF analysis reveals small peroxide-like defects in CeO2 and mono- and di-interstitial clusters in UO2. Our findings imply that nanocrystallinity has negative effects on a material’s response to highly ionizing radiation. These results shed more light onto the interplay of particle size and cation redox behavior and their effect on defect production in an important class of materials, an insight that is essential in developing advanced materials for energy-related applications.
Published: 2020

10. Dissolution of radioactive, cesium-rich microparticles released from the Fukushima Daiichi Nuclear Power Plant in simulated lung fluid, pure-water, and seawater

Author: Gareth T. W. Law, Kazuya Morooka, Eitaro Kurihara, Genki Furuki, Ryohei Ikehara, Toshihiko Ohnuki, Kenji Horie, William R. Bower, Mizuki Suetake, Shinya Yamasaki, Tatsuki Komiya, Yuriko Nakano, Rodney C. Ewing, Mami Takehara, Satoshi Utsunomiya, Bernd Grambow, IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), Laboratoire de physique subatomique et des technologies associées (SUBATECH), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Department of Geological Sciences, University of Michigan, University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, and Department of Chemistry
Subjects: MECHANISM, Fukushima Nuclear Accident, PH, Health, Toxicology and Mutagenesis, 0208 environmental biotechnology, 116 Chemical sciences, Cesium, 02 engineering and technology, BASALTIC GLASS DISSOLUTION, 010501 environmental sciences, 01 natural sciences, Matrix (chemical analysis), Soil, Japan, Solubility, Dissolution, TEMPERATURE, ComputingMilieux_MISCELLANEOUS, General Medicine, Pollution, HYDROXYAPATITE, Radioactivity, Cesium Radioisotopes, Environmental chemistry, Nuclear Power Plants, Ultrapure water, [CHIM.RADIO]Chemical Sciences/Radiochemistry, Water Pollutants, Radioactive, Environmental Engineering, chemistry.chemical_element, Radiation Monitoring, Environmental Chemistry, Seawater, RATES, SILICA, KINETICS, 0105 earth and related environmental sciences, CONSEQUENCES, Silicates, Public Health, Environmental and Occupational Health, ALLOY, Water, General Chemistry, 020801 environmental engineering, chemistry, 13. Climate action, Caesium, Soil water, Glass
Abstract: To understand the chemical durability of highly radioactive cesium-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant in March 2011, we have, for the first time, performed systematic dissolution experiments with CsMPs isolated from Fukushima soils (one sample with 108 Bq and one sample with 57.8 Bq of Cs-137) using three types of solutions: simulated lung fluid, ultrapure water, and artificial sea water, at 25 and 37 degrees C for 1-63 days. The Cs-137 was released rapidly within three days and then steady-state dissolution was achieved for each solution type. The steady-state Cs-137 release rate at 25 degrees C was determined to be 4.7 x 10(3), 1.3 x 10(3), and 1.3 x 10(3) Bq . m(-2)s(-1) for simulated lung fluid, ultrapure water, and artificial sea water, respectively. This indicates that the simulated lung fluid promotes the dissolution of CsMPs. The dissolution of CsMPs is similar to that of Si-based glass and is affected by the surface moisture conditions. In addition, the Cs release from the CsMPs is constrained by the rate-limiting dissolution of silicate matrix. Based on our results, CsMPs with similar to 2 Bq, which can be potentially inhaled and deposited in the alveolar region, are completely dissolved after >35 years. Further, CsMPs could remain in the environment for several decades; as such, CsMPs are important factors contributing to the long-term impacts of radioactive Cs in the environment. (C) 2019 Elsevier Ltd. All rights reserved.
Published: 2019
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11. Isotopic Fingerprint of Uranium Accumulation and Redox Cycling in Floodplains of the Upper Colorado River Basin

Author: Pierre Lefebvre, K. L. Weaver, Kate Maher, John R. Bargar, Noah E. Jemison, Kimberly V. Lau, Vincent Noel, Kenneth H. Williams, Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'aérologie (LAERO), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, University of Illinois System, Earth Science Division [LBNL Berkeley] (ESD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), École normale supérieure - Paris (ENS-PSL), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Water Pollutants, Radioactive, Geologic Sediments, Colorado, Floodplain, Drainage basin, chemistry.chemical_element, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Fractionation, 010501 environmental sciences, 01 natural sciences, Redox, Isotopic signature, Rivers, MD Multidisciplinary, Environmental Chemistry, Water Pollutants, Radioactive, Groundwater, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Sediment, General Chemistry, Uranium, 6. Clean water, chemistry, Environmental chemistry, Environmental science, Oxidation-Reduction, Environmental Sciences
Abstract: International audience; Uranium (U) groundwater contamination is a major concern at numerous former mining and milling sites across the Upper Colorado River Basin (UCRB), USA, where U(IV)-bearing solids have accumulated within naturally reduced zones (NRZs). Understanding the processes governing U reduction and oxidation within NRZs is critical for assessing the persistence of U in groundwater. To evaluate the redox cycling of uranium, we measured the U concentrations and isotopic compositions (δ238U) of sediments and pore waters from four study sites across the UCRB that span a gradient in sediment texture and composition. We observe that U accumulation occurs primarily within fine-grained (low-permeability) NRZs that show active redox variations. Low-permeability NRZs display high accumulation and low export of U, with internal redox cycling of U. In contrast, within high-permeability NRZs, U is remobilized under oxidative conditions, possibly without any fractionation, and transported outside the NRZs. The low δ238U of sediments outside of defined NRZs suggests that these reduced zones act as additional U sources. Collectively, our results indicate that fine-grained NRZs have a greater potential to retain uranium, whereas NRZs with higher permeability may constitute a more-persistent but dilute U source.
Published: 2019
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12. Grain size effects on irradiated CeO2, ThO2, and UO2

Author: William F. Cureton, Chien-Hung Chen, Rodney C. Ewing, Jie Lian, Christina Trautmann, Jeffrey Walters, Cameron L. Tracy, Gianguido Baldinozzi, Maik Lang, Raul I. Palomares, The University of Tennessee [Knoxville], Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Rensselaer Polytechnic Institute (RPI), Technische Universität Darmstadt (TU Darmstadt), and Helmholtz zentrum für Schwerionenforschung GmbH (GSI)
Subjects: Materials science, Polymers and Plastics, Analytical chemistry, 02 engineering and technology, 01 natural sciences, symbols.namesake, 0103 physical sciences, Irradiation, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Metals and Alloys, 021001 nanoscience & nanotechnology, Grain size, Nanocrystalline material, Electronic, Optical and Magnetic Materials, Microcrystalline, Transmission electron microscopy, X-ray crystallography, Ceramics and Composites, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Grain boundary, 0210 nano-technology, Raman spectroscopy
Abstract: Microcrystalline and nanocrystalline UO2, ThO2, and CeO2 (∼2 μm and∼20 nm particle size, respectively) were irradiated with 946 MeV Au ions at room temperature and characterized by synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. All samples show a small increase in unit cell parameter as a function of ion fluence (0.17 ± 0.03% for CeO2 and 0.11 ± 0.03% for ThO2), except microcrystalline UO2, which displays a small contraction of the unit cell (−0.06 ± 0.02%). Raman spectroscopy measurements of microcrystalline UO2 indicate an increase in nonstoichiometry after irradiation. All bulk materials are subject to an increase in heterogeneous microstrain, most notably UO2, implying that the relatively small changes in unit cell parameter are accompanied by substantial local disorder induced by isolated defects. The magnitude of volumetric swelling for all materials is larger in the nanocrystalline form as compared with the microcrystalline form (0.38 ± 0.60% for CeO2, 0.14 ± 0.03% for ThO2, and 0.52 ± 0.13% for UO2). ThO2 shows the smallest difference in swelling between the microcrystalline and nanocrystalline samples (∼0.03%). All nanocrystalline materials exhibit irradiation-induced grain coarsening along with a decrease in heterogeneous microstrain with increasing ion fluence, except nanocrystalline CeO2, which shows no observable change in grain size and a slight increase in heterogeneous microstrain attributed to the accelerated formation of a secondary Ce11O20 phase evidenced in the X-ray diffraction data, present in both nanocrystalline and microcrystalline materials. Surprisingly, nanocrystalline UO2 exhibits a significant degree of swelling indicative of a decrease in oxygen content along with an increase in disorder induced by oxygen loss at grain boundaries during irradiation, based on the analysis of X-ray diffraction and Raman spectroscopy.
Published: 2018
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13. Effects of Crystallite Size on the Response of CeO2, ThO2, and UO2 to Highly Ionizing Radiation

Author: Cureton, William, Palomares, Raul, Walters, Jeffrey, Tracy, Cameron, Chen, Curtis, Ewing, Rodney, Baldinozzi, Gianguido, Lian, Jie, Trautmann, Christina, Lang, Maik, The University of Tennessee [Knoxville], Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Laboratoire Structures, Propriétés et Modélisation des solides (SPMS), Institut de Chimie du CNRS (INC)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Rensselaer Polytechnic Institute (RPI), Helmholtz zentrum für Schwerionenforschung GmbH (GSI), and Baldinozzi, Gianguido
Subjects: [CHIM.MATE] Chemical Sciences/Material chemistry, [CHIM.RADIO] Chemical Sciences/Radiochemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM.MATE]Chemical Sciences/Material chemistry, [CHIM.CRIS] Chemical Sciences/Cristallography, [CHIM.RADIO]Chemical Sciences/Radiochemistry, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract: International audience; Radiation response is often a key limiting factor to the extension of nuclear fuel lifetimes and the development of advanced fuel materials. Recently, it has been shown that the response of CeO2, ThO2, and UO3 to highly ionizing radiation is highly dependent on redox response [Tracy et al., Nature Communications (2015)]. When exposed to this radiation, cations in the material are subject to changes in valence which drives swelling and microstrain as irradiation-induced defects accumulate. In an effort to mitigate these effects, many have studied nanostructured materials because they incorporate high defect sink strengths [Rose et al., Nanostructured Materials (1995), Nita et al., Journal of Nuclear Materials (2004)]. In this work, we present new insights into how crystallite size affects irradiation-induced redox response and defect accumulation in of isostructural CeO2, ThO2, and UO2. Using highly ionizing swift heavy ions (946 MeV Au ions) at the UNILAC accelerator of the GSI Helmholtz Center, we irradiated microcrystalline and nanocrystalline materials of different compositions known to reduce (CeO2), remain stoichiometric (ThO2), and oxidize (UO2) under ionizing conditions. Irradiated samples were characterized by synchrotron X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Each composition exhibited a distinct response between microcrystalline and nanocrystalline forms, such as magnitude of volumetric swelling (Fig. 1), driven mainly by redox processes. Our findings imply that nanocrystallinity has negative effects on a materials response to highly ionizing radiation. These results have implications in engineering safer, more tolerant materials for current and future energy-related applications.
Published: 2018

14. Contrasting magma types and timing of intrusion in the Permian layered mafic complex of Mont Collon (Western Alps, Valais, Switzerland): evidence from U/Pb zircon and 40Ar/39Ar amphibole dating

Author: Henriette Lapierre, Hans-Ruedi Pfeifer, Urs Schaltegger, Andreas Mulch, François Bussy, Philippe Monjoie, Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Institute of Mineralogy and Geochemistry, IMG-ANTHROPOLE, Université de Lausanne (UNIL), Department of Mineralogy, University of Geneva [Switzerland], Department of Geological and Environmental Sciences [Stanford] (GES), Stanford University [Stanford], Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, and Stanford University-Stanford University
Subjects: Dike, 010504 meteorology & atmospheric sciences, Gabbro, Geochronology, geochronology, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Permian, 010502 geochemistry & geophysics, 01 natural sciences, Ultramafic rock, ddc:550, 0105 earth and related environmental sciences, geography, Felsic, geography.geographical_feature_category, Continental crust, Western Alps, Geology, 15. Life on land, [SDU]Sciences of the Universe [physics], Kaersutite, Mafic, Mantle, mantle, gabbro, Zircon
Abstract: International audience; We have selected and dated three contrasting rock-types representative of the magmatic activity within the Permian layered mafic complex of Mont Collon, Austroalpine Dent Blanche nappe, Western Alps. A pegmatitic gabbro associated to the main cumulus sequence yields a concordant U/Pb zircon age of 284.2 ± 0.6 Ma, whereas a pegmatitic granite dike crosscutting the latter yields a concordant age of 282.9 ± 0.6 Ma. A Fe-Ti-rich ultrabasic lamprophyre, crosscutting all other lithologies of the complex, yields an 40Ar/39Ar plateau age of 260.2 ± 0.7 Ma on a kaersutite concentrate. All ages are interpreted as magmatic. Sub-contemporaneous felsic dikes within the Mont Collon complex are ascribed to anatectic back-veining from the country-rock, related to the emplacement of the main gabbroic body in the continental crust, which is in accordance with new isotopic data. The lamprophyres have isotopic compositions typical of a depleted mantle, in contrast to those of the cumulate gabbros, close to values of the Bulk Silicate Earth. This indicates either contrasting sources for the two magma pulses – the subcontinental lithospheric mantle for the gabbros and the underlying asthenosphere for the lamprophyres – or a single depleted lithospheric source with variable degrees of crustal contamination of the gabbroic melts during their emplacement in the continental crust. The Mont Collon complex belongs to a series of Early Permian mafic massifs, which emplaced in a short time span about 285-280 Ma ago, in a limited sector of the post-Variscan continental crust now corresponding to the Austroalpine/Southern Alpine domains and Corsica. This magmatic activity was controlled in space and time by crustal-scale transtensional shear zones.
Published: 2018
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15. Oxidation of Ni-Rich Mangrove Sediments after Isolation from the Sea (Dumbea Bay, New Caledonia) : Fe and Ni Behavior and Environmental Implications

Author: Farid Juillot, Ludovic Delbes, John R. Bargar, Georges Ona-Nguema, Guillaume Morin, Gabrielle Dublet, Fabien Maillot, Gregory Marakovic, Vincent Noel, Cyril Marchand, Eric Viollier, Gordon E. Brown, François Prévot, Koniambo Nickel SAS KNS, BP 679, Kone 98860, New Caledonia, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Koniambo Nickel SAS (KNS), SLAC National Accelerator Laboratory (SLAC), Stanford University, Surface and Aqueous Geochemistry Group [Stanford], Stanford Synchrotron Radiation Lightsource (SSRL SLAC), Stanford University-Stanford University-SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University-Advanced Light Source [LBNL Berkeley] (ALS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Lawrence Berkeley National Laboratory [Berkeley] (LBNL), SLAC Natl Accelerator Lab, Dept Photon Sci, 2575 Sand Hill Rd,MS 69, Menlo Pk, CA 94025 USA, Koniambo Nickel SAS (KNS) United States Department of Energy (DOE)DE-AC02-76SF00515United States Department of Energy (DOE) United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of General Medical Sciences (NIGMS)P41GM103393U.S. Department of Energy, Office of Biological and Environmental Research (BER), Subsurface Biogeochemical Research (SBR) program DE-AC02-76SF00515, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Advanced Light Source [LBNL Berkeley] (ALS), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Stanford Synchrotron Radiation Lightsource (SSRL SLAC)
Subjects: inorganic chemicals, absorption spectroscopy, Atmospheric Science, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010501 environmental sciences, engineering.material, 010502 geochemistry & geophysics, Mangrove sediments, 01 natural sciences, Redox, Sink (geography), X-ray, Geochemistry and Petrology, Oxidizing agent, 14. Life underwater, Dissolution, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Schwertmannite, oxidation processes, X-ray absorption spectroscopy, 15. Life on land, Anoxic waters, anthropogenic pressure, pyrite, iron and nickel, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Environmental chemistry, engineering, Pyrite, Mangrove, Geology
Abstract: International audience; Formation of Fe-sulfides in anoxic horizons of mangrove sediments makes this ecosystem a potential long-term sink for metal contaminants in the intertropical region. Increasing anthropogenic pressure on coastal areas can alter the physicochemical of mangrove sediments by modifying their redox state, affecting directly the rate of Fe-sulfides that mediate accumulation of metal contaminant. Here, we show that isolation from the sea, due to land use planning, directly modify the redox state of mangrove sediments from reducing condition to oxidizing condition, affecting the stability of Ni-accumulating Fe-sulfides. Unusual suboxic/oxic conditions are indeed observed at intermediate depths in these mangrove sediments and favor the oxidative dissolution of Ni-pyrite (Fe1-xNixS2) that initially formed under anoxic/suboxic conditions. This reaction leads to a significant release of aqueous HS-, Fe2+ and Ni2+ at the redox boundary. HS- and Fe2+ oxidize into SO42- and Fe3+ and precipitate as schwertmannite (Fe8O8(OH)(6)SO4), leading to acidification of the pore-waters. Meanwhile, aqueous Ni2+ is mostly leached downward in the underlying anoxic layers of the sediment where it sorbs at the surface of pyrite and/or incorporates in the structure of newly formed pyrites. These results emphasize the potential of Fe-sulfides for mitigating the impact of the oxidation of former Ni-rich mangrove sediments, as long as the anoxic conditions are preserved at depth. This assumption can be expanded to other divalent metals and should be applicable to a larger set of mangrove ecosystems worldwide.
Published: 2017
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16. Inter-calibration of a proposed new primary reference standard AA-ETH Zn for zinc isotopic analysis

Author: Shuofei Dong, Tim M. Conway, Laura E. Wasylenki, Moneesha Samanta, Rebekah E. T. Moore, Corey Archer, Joey Nelson, Mark Rehkämper, Morten B. Andersen, Yoshiki Sohrin, Olivier Rouxel, Michael J. Ellwood, Shotaro Takano, Christophe Cloquet, Ki-Cheol Shin, Science and Technology Facilities Council (STFC), Institute of Geochemistry and Petrology [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Australian National University (ANU), Department of Earth Science and Engineering [Imperial College London], Imperial College London, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Research Institute for Humanity and Nature (RIHN), Kyoto University [Kyoto], Indiana University [Bloomington], and Indiana University System
Subjects: 0306 Physical Chemistry (Incl. Structural), 010401 analytical chemistry, Inter calibration, Analytical chemistry, chemistry.chemical_element, Mineralogy, Zinc, Standard solution, Q1, 010502 geochemistry & geophysics, 01 natural sciences, Isotopic composition, 0104 chemical sciences, Analytical Chemistry, chemistry, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Isotopes of zinc, Calibration, Reference standards, 0301 Analytical Chemistry, ComputingMilieux_MISCELLANEOUS, Spectroscopy, 0105 earth and related environmental sciences, Isotope analysis
Abstract: We have prepared a large volume of pure, concentrated and homogenous zinc standard solution. This new standard solution is intended to be used as a primary reference standard for the zinc isotope community, and to serve as a replacement for the nearly exhausted current reference standard, the so-called JMC-Lyon Zn. The isotopic composition of this new zinc standard (AA-ETH Zn) has been determined through an inter-laboratory calibration exercise, calibrated against the existing JMC-Lyon standard, as well as the certified Zn reference standard IRMM-3702. The data show that the new standard is isotopically indistinguishable from the IRMM-3702 zinc standard, with a weighted δ66/64Zn value of 0.28 ± 0.02‰ relative to JMC-Lyon. We suggest that this new standard be assigned a δ66/64Zn value of +0.28‰ for reporting of future Zn isotope data, with the rationale that all existing published Zn isotope data are presented relative to the JMC-Lyon standard. Therefore our proposed presentation allows for a direct comparison with all previously published data, and that are directly traceable to a certified reference standard, IRMM-3702 Zn. This standard will be made freely available to all interested labs through contact with the corresponding author., Journal of Analytical Atomic Spectrometry, 32 (2), ISSN:0267-9477, ISSN:1364-5544
Published: 2017
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17. Energetics of a Uranothorite (Th 1– x U x SiO 4 ) Solid Solution

Author: Nicolas Dacheux, Alexandra Navrotsky, Christophe Poinssot, Rodney C. Ewing, Xiaofeng Guo, Stéphanie Szenknect, Hongwu Xu, Adel Mesbah, Di Wu, Nicolas Clavier, University of California [Davis] (UC Davis), University of California (UC), Interfaces de Matériaux en Evolution (LIME), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Peter A. Rock Thermochemistry Laboratory, University of California Davis, University of California (UC)-University of California (UC), University of California, Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and University of California-University of California
Subjects: Exothermic reaction, Thermogravimetric analysis, Materials science, General Chemical Engineering, Analytical chemistry, Oxide, 02 engineering and technology, Calorimetry, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Differential scanning calorimetry, Metastability, Materials Chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Standard enthalpy of formation, chemistry, Physical chemistry, 0210 nano-technology, Solid solution
Abstract: High-temperature oxide melt solution calorimetric measurements were completed to determine the enthalpies of formation of the uranothorite, (USiO4)x–(ThSiO4)1–x, solid solution. Phase-pure samples with x values of 0, 0.11, 0.21, 0.35, 0.71, and 0.84 were prepared, purified, and characterized by powder X-ray diffraction, electron probe microanalysis, thermogravimetric analysis and differential scanning calorimetry coupled with in situ mass spectrometry, and high-temperature oxide melt solution calorimetry. This work confirms the energetic metastability of coffinite, USiO4, and U-rich intermediate silicate phases with respect to a mixture of binary oxides. However, variations in unit cell parameters and negative excess volumes of mixing, coupled with strongly exothermic enthalpies of mixing in the solid solution, suggest short-range cation ordering that can stabilize intermediate compositions, especially near x = 0.5.
Published: 2016
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18. First experimental determination of the solubility constant of coffinite

Author: H.P. Brau, Xavier F. Le Goff, Adel Mesbah, Stéphanie Szenknect, Nicolas Dacheux, Nicolas Clavier, Rodney C. Ewing, T. Cordara, Christophe Poinssot, Interfaces de Matériaux en Evolution (LIME), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Etude de la Matière en Mode Environnemental (L2ME), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
Subjects: Supersaturation, Aqueous solution, Chemistry, Analytical chemistry, Mineralogy, Solubility equilibrium, [CHIM.MATE]Chemical Sciences/Material chemistry, 010501 environmental sciences, solubility constant, 010502 geochemistry & geophysics, uranium silicate, 01 natural sciences, uraninite, coffinitization, Gibbs free energy, symbols.namesake, Uraninite, coffinite, Geochemistry and Petrology, silica, symbols, Coffinite, Quartz, Dissolution, 0105 earth and related environmental sciences
Abstract: Dissolution experiments have been performed in order to determine the solubility constant of coffinite, USiO4. Several assemblages of phases were used in under-saturated experiments performed in 0.1 mol L−1 HCl under Ar atmosphere, as well as in air. These samples were fully-characterized and were composed of either USiO4, solely, or USiO4 and additional oxide byproducts that resulted from the synthesis procedure. The solubility constant of coffinite was determined at 25 °C and 1 bar (log *KS°(USiO4, cr) = −5.25 ± 0.05), as well as the standard free energy of formation of coffinite (ΔfG°(298 K) = −1867.6 ± 3.2 kJ mol−1), which enables one to infer the relative stability of coffinite and uraninite as a function of groundwater composition. Geochemical simulations using PHREEQC 2 software and the Thermochimie data base indicate that coffinite precipitates at 25 °C under reducing conditions, at pH = 6, for H4SiO4(aq) concentration of 7 × 10−5 mol L−1 and U(OH)4(aq) concentration of 10−11 mol L−1. The ΔfG° value determined was used to calculate the standard free energy associated with the formation of coffinite from a mixture of uraninite and quartz. The value obtained (Δr,oxG° = 20.6 ± 5.2 kJ mol−1) indicates unambiguously that coffinite is less stable than the quartz + uraninite mixture at 25 °C. Geochemical simulations using PHREEQC 2 software indicate that coffinite precipitates in solutions supersaturated with respect to UO2(cr), but undersaturated with respect to UO2(am) in aqueous solutions with silica concentrations typical of groundwater. These favorable conditions during the formation of sedimentary uranium ore deposits, as well as slow dissolution kinetics, explain the common occurrence of coffinite.
Published: 2016
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19. The influence on Fe content on Raman spectra and unit cell parameters of magnesite–siderite solid solutions

Author: Guillaume Fiquet, E. Boulard, François Guyot, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Diffraction, Mineral, 010504 meteorology & atmospheric sciences, Analytical chemistry, Electron microprobe, 010502 geochemistry & geophysics, Raman spectroscopy Siderite Magnesite, 01 natural sciences, Chemistry Unit cells parameters, chemistry.chemical_compound, symbols.namesake, Siderite, chemistry, Geochemistry and Petrology, symbols, Carbonate, General Materials Science, Raman spectroscopy, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy, 0105 earth and related environmental sciences, Magnesite, Solid solution
Abstract: International audience; Characterization of a set of iron-magnesium carbonate mineral samples was done by Raman spectroscopy, X-ray diffraction and electron microprobe. The evolution of unit cell parameters and of the Raman peak positions of the three vibrations modes T, L and 2m2 are reported as a function of the Fe content. Fourteen samples spanning the compositional range from FeCO3 siderite to MgCO3 magnesite were used for this calibration. Such a calibration provides a non-destructive and rapid method for extracting mineral chemistry, suitable for samples that cannot be moved and need immediate analysis or for samples that cannot be destructed or that are in small quantities.
Published: 2011
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20. Physico-Chemical Heterogeneity of Organic-Rich Sediments in the Rifle Aquifer, CO: Impact on Uranium Biogeochemistry

Author: John R. Bargar, Florent Lallier, Kenneth H. Williams, Don Q. Pham, Juan S. Lezama Pacheco, Noémie Janot, Debra M. Hausladen, Kate Maher, Vincent Noel, Philip E. Long, Scott Fendorf, Tim M. O'Brien, Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Department of Earth System Science [Stanford] (ESS), Stanford EARTH, Université de Lorraine (UL), Department of Geological Sciences [Stanford] (GS), Earth Science Division [LBNL Berkeley] (ESD), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)
Subjects: Geologic Sediments, Water Pollutants, Radioactive, Colorado, 010504 meteorology & atmospheric sciences, chemistry.chemical_element, Color, Aquifer, 010501 environmental sciences, 01 natural sciences, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Environmental Chemistry, Water Pollutants, Organic matter, Organic Chemicals, Particle Size, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Radioactive, Groundwater, 0105 earth and related environmental sciences, Total organic carbon, chemistry.chemical_classification, Hydrology, geography, geography.geographical_feature_category, Biogeochemistry, Sediment, General Chemistry, Uranium, 6. Clean water, Carbon, Plume, X-Ray Absorption Spectroscopy, chemistry, 13. Climate action, Environmental chemistry, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Oxidation-Reduction, Environmental Sciences, Geology, Sulfur
Abstract: © 2015 American Chemical Society. The Rifle alluvial aquifer along the Colorado River in west central Colorado contains fine-grained, diffusion-limited sediment lenses that are substantially enriched in organic carbon and sulfides, as well as uranium, from previous milling operations. These naturally reduced zones (NRZs) coincide spatially with a persistent uranium groundwater plume. There is concern that uranium release from NRZs is contributing to plume persistence or will do so in the future. To better define the physical extent, heterogeneity and biogeochemistry of these NRZs, we investigated sediment cores from five neighboring wells. The main NRZ body exhibited uranium concentrations up to 100 mg/kg U as U(IV) and contains ca. 286 g of U in total. Uranium accumulated only in areas where organic carbon and reduced sulfur (as iron sulfides) were present, emphasizing the importance of sulfate-reducing conditions to uranium retention and the essential role of organic matter. NRZs further exhibited centimeter-scale variations in both redox status and particle size. Mackinawite, greigite, pyrite and sulfate coexist in the sediments, indicating that dynamic redox cycling occurs within NRZs and that their internal portions can be seasonally oxidized. We show that oxidative U(VI) release to the aquifer has the potential to sustain a groundwater contaminant plume for centuries. NRZs, known to exist in other uranium-contaminated aquifers, may be regionally important to uranium persistence.
Published: 2015
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21. Signature of a polyamorphic transition in the THz spectrum of vitreous GeO2

Author: Filippo Bencivenga, Ho-kwang Mao, Roberto Verbeni, Shibing Wang, Daniele Antonangeli, Yong Q. Cai, C. N. Kodituwakku, Alfred Q. R. Baron, Satoshi Tsutsui, Yan Li, Andrea Battistoni, Alessandro Cunsolo, Dima Bolmatov, National Synchrotron Light Source II, Brookhaven National Laboratory [Upton, NY] (BNL), UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY)-U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY)-U.S. Department of Energy [Washington] (DOE), American Physical Society, Research Road, Ridge, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, I-34012 Trieste, Italy, Dipartimento di Fisica, Università degli studi di Trieste = University of Trieste, European Synchrotron Radiation Facility (ESRF), Japan Synchrotron Radiation Research Institute [Hyogo] (JASRI), RIKEN SPring-8 Center [Hyogo] (RIKEN RSC), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Geophysical Laboratory [Carnegie Institution], Carnegie Institution for Science, Center for High Pressure Science & Technology Advanced Research, Center for High Pressure Science & Technology Advanced Research (HPSTAR), U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Università degli studi di Trieste, and Carnegie Institution for Science [Washington]
Subjects: Spectral shape analysis, Materials science, Phonon, Terahertz radiation, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Article, Condensed Matter::Materials Science, Physics - Chemical Physics, 0103 physical sciences, Dispersion (optics), 010306 general physics, Condensed Matter - Statistical Mechanics, Chemical Physics (physics.chem-ph), Range (particle radiation), Condensed Matter - Materials Science, Multidisciplinary, Condensed matter physics, Statistical Mechanics (cond-mat.stat-mech), Scattering, Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, 021001 nanoscience & nanotechnology, Rutile, [SDU]Sciences of the Universe [physics], 0210 nano-technology, Ambient pressure
Abstract: The THz spectrum of density fluctuations, $S(Q, \omega)$, of vitreous GeO$_2$ at ambient temperature was measured by inelastic x-ray scattering from ambient pressure up to pressures well beyond that of the known $\alpha$-quartz to rutile polyamorphic (PA) transition. We observe significant differences in the spectral shape measured below and above the PA transition, in particular, in the 30-80 meV range. Guided by first-principle lattice dynamics calculations, we interpret the changes in the phonon dispersion as the evolution from a quartz-like to a rutile-like coordination. Notably, such a crossover is accompanied by a cusp-like behavior in the pressure dependence of the elastic response of the system. Overall, the presented results highlight the complex fingerprint of PA phenomena on the high-frequency phonon dispersion., Comment: 18 pages, 5 figures
Published: 2015
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22. Pressure-induced phase transition in MnCO3and its implications on the deep carbon cycle

Author: Boulard, Eglantine, Goncharov, Alexander F., Blanchard, Marc, L. Mao, Wendy, Matériaux, Rayonnements, Structure (MRS), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Geophysical Laboratory [Carnegie Institution], Carnegie Institution for Science [Washington], Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Photon Science, SLAC National Accelerator Laboratory (SLAC), Matériaux, Rayonnements, Structure (NEEL - MRS), and Carnegie Institution for Science
Subjects: [PHYS]Physics [physics]
Abstract: International audience; The high-pressure behavior of manganese-rich carbonate, rhodochrosite, has been characterizedup to 62GPa by synchrotron-based midinfrared spectroscopy and X-ray diffraction. Modifications in boththe infrared spectra and the X-ray diffraction patterns were observed above ~35GPa, indicating the presenceof a high-pressure phase transition at these pressures. We found that rhodochrosite adopts a structure closeto CaCO3-VI with a triclinic unit cell (a=2.87Å, b = 4.83 Å, c=5.49Å, α = 99.86°, β = 94.95°, and γ=90.95° at62 GPa). Using first-principles calculations based on density functional theory, we confirmed these observationsand assigned modes in the new infrared signature of the high-pressure phase. These results suggest thathigh-pressure metastable phase of calcite may play an important role in carbon storage and transport in thedeep Earth.
Published: 2015
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23. Thermodynamics of formation of coffinite, USiO4

Author: Xiaofeng Guo, Adel Mesbah, Dirk Bosbach, Sabrina Labs, Stéphanie Szenknect, Nicolas Clavier, Alexandra Navrotsky, Rodney C. Ewing, Sergey V. Ushakov, Nicolas Dacheux, Hildegard Curtius, Peter C. Burns, Christophe Poinssot, University of California [Davis] (UC Davis), University of California (UC), Interfaces de Matériaux en Evolution (LIME), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Metallurgical and Materials Engineering, Universidade de São Paulo = University of São Paulo (USP)-Escola Politécnica, Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology (KIT), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Peter A. Rock Thermochemistry Laboratory, University of California Davis, University of California (UC)-University of California (UC), University of California, Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Universidade de São Paulo (USP)-Escola Politécnica, and University of California-University of California
Subjects: Materials science, Analytical chemistry, Oxide, Mineralogy, 02 engineering and technology, Calorimetry, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010502 geochemistry & geophysics, 01 natural sciences, U(IV) minerals, Hydrothermal circulation, uranium, chemistry.chemical_compound, Differential scanning calorimetry, coffinite, [CHIM]Chemical Sciences, Coffinite, Quartz, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Multidisciplinary, USiO4, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Standard enthalpy of formation, Thermogravimetry, chemistry, 13. Climate action, Physical Sciences, 0210 nano-technology, calorimetry, [CHIM.RADIO]Chemical Sciences/Radiochemistry
Abstract: Coffinite, USiO4, is an important U(IV) mineral, but its thermodynamic properties are not well-constrained. In this work, two different coffinite samples were synthesized under hydrothermal conditions and purified from a mixture of products. The enthalpy of formation was obtained by high-temperature oxide melt solution calorimetry. Coffinite is energetically metastable with respect to a mixture of UO2 (uraninite) and SiO2 (quartz) by 25.6 ± 3.9 kJ/mol. Its standard enthalpy of formation from the elements at 25 °C is −1,970.0 ± 4.2 kJ/mol. Decomposition of the two samples was characterized by X-ray diffraction and by thermogravimetry and differential scanning calorimetry coupled with mass spectrometric analysis of evolved gases. Coffinite slowly decomposes to U3O8 and SiO2 starting around 450 °C in air and thus has poor thermal stability in the ambient environment. The energetic metastability explains why coffinite cannot be synthesized directly from uraninite and quartz but can be made by low-temperature precipitation in aqueous and hydrothermal environments. These thermochemical constraints are in accord with observations of the occurrence of coffinite in nature and are relevant to spent nuclear fuel corrosion.
Published: 2015
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24. Tetrahedrally coordinated carbonates in Earth’s lower mantle

Author: Giulia Galli, Zhenxian Liu, Wendy L. Mao, E. Boulard, Ding Pan, Matériaux, Rayonnements, Structure (MRS), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institute for Molecular Engineering, University of Chicago, Geophysical Laboratory [Carnegie Institution], Carnegie Institution for Science [Washington], SLAC National Accelerator Laboratory (SLAC), and Stanford University
Subjects: Condensed Matter - Materials Science, Multidisciplinary, Materials science, Mineral, Subduction, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Geochemistry, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, General Chemistry, General Biochemistry, Genetics and Molecular Biology, chemistry.chemical_compound, Viscosity, chemistry, 13. Climate action, Phase (matter), Carbonate, Earth (classical element)
Abstract: Carbonates are the main species that bring carbon deep into our planet through subduction. They are an important rock-forming mineral group, fundamentally distinct from silicates in the Earth's crust in that carbon binds to three oxygen atoms, while silicon is bonded to four oxygens. Here we present experimental evidence that under the sufficiently high pressures and high temperatures existing in the lower mantle, ferromagnesian carbonates transform to a phase with tetrahedrally coordinated carbons. Above 80 GPa, in situ synchrotron infrared experiments show the unequivocal spectroscopic signature of the high-pressure phase of (Mg,Fe)CO3. Using ab-initio calculations, we assign the new infrared signature to C-O bands associated with tetrahedrally coordinated carbon with asymmetric C-O bonds. Tetrahedrally coordinated carbonates are expected to exhibit substantially different reactivity than low-pressure threefold coordinated carbonates, as well as different chemical properties in the liquid state. Hence, this may have significant implications for carbon reservoirs and fluxes, and the global geodynamic carbon cycle.
Published: 2015
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25. STRUCTURAL ENVIRONMENTS AROUND MOLYBDENUM IN SILICATE GLASSES AND MELTS. I. INFLUENCE OF COMPOSITION AND OXYGEN FUGACITY ON THE LOCAL STRUCTURE OF MOLYBDENUM

Author: Anne Guesdon, François Farges, Ralf Siewert, Guillaume Morin, Gordon E. Brown, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Minéralogie, Pétrologie (MP), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), and Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Inorganic chemistry, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, engineering.material, Molybdate, 010502 geochemistry & geophysics, Anorthite, glasses, 01 natural sciences, Albite, chemistry.chemical_compound, molybdenum, Geochemistry and Petrology, Mineral redox buffer, oxygen fugacity, 0105 earth and related environmental sciences, Extended X-ray absorption fine structure, Chemistry, 021001 nanoscience & nanotechnology, X-ray absorption fine structure, 13. Climate action, Molybdenum, redox, Molybdenite, melts, engineering, 0210 nano-technology, XAFS spectroscopy, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: The coordination chemistry of molybdenum was investigated in nine series of synthetic silicate glasses, including sodium disilicate (NS2), sodium trisilicate (NS3), albite (Ab), anorthite (An), Ab50An50, Ab30An70, diopside (DI), rhyolite (RH), and basalt (BA), using electron paramagnetic resonance (EPR) and X-ray absorption fine structure (XAFS) spectroscopies. The Mo content of these glasses ranges from 300 ppm to 3 wt.%. On the basis of results derived from high-resolution X-ray absorption near-edge structure (XANES) spectroscopy, molybdenum is present primarily as molybdate moieties [Mo(VI)O42−] in most of the glass compositions prepared at f (O2) values ranging from 1 atm to 10−12 atm (temperatures ranging from 1100 to 1700°C, i.e., from air to IW+4). Analysis of extended XAFS (EXAFS) spectra of these glasses indicates an average Mo–O distance of ~1.76(1) A. No evidence for second-neighbor Si or Al around Mo was found in any of the glasses, confirming that molybdate moieties are not connected to the tetrahedral framework, in agreement with Pauling bond-valence predictions. The presence of molybdate moieties in regions of these glasses enriched in network modifiers helps explain why crystalline molybdates can nucleate easily in silicate glasses (and, by extension, in the corresponding melts). In the highly polymerized glass compositions (such as “Ab” or “RH”), Mo(VI)O66− moieties also exist, but at minor levels (
Published: 2006
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26. Scientific Advances Made Possible by User Facilities

Author: Georges Calas, Russell J. Hemley, Gordon E. Brown, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Geophysical Laboratory [Carnegie Institution], Carnegie Institution for Science, Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Carnegie Institution for Science [Washington]
Subjects: Geophysical Processes, Engineering, business.industry, Ecology, 010502 geochemistry & geophysics, 01 natural sciences, synchrotron radiation sources, 13. Climate action, Geochemistry and Petrology, Multidisciplinary approach, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), neutron sources, national scientific user facilities, 010306 general physics, business, Environmental planning, Earth science research, 0105 earth and related environmental sciences
Abstract: National scientific user facilities are becoming increasingly available to many different scientific communities in a number of countries. There is a growing use of these facilities by Earth and environmental scientists to study a broad range of materials and processes under realistic P–T and environmental conditions at unprecedented levels of energy and spatial resolution and elemental and isotopic sensitivity. The results of these studies are providing new insights into biogeochemical processes operating at Earth's surface as well as petrological, geochemical, and geophysical processes in Earth's interior. The availability of national user facilities is changing scientific approaches and is leading to multidisciplinary studies that were not possible a decade ago.
Published: 2006
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27. Submarine landslides in the Santa Barbara Channel as potential tsunami sources

Author: Norm Maher, H. G. Greene, Philip Watts, C. E. Paull, Peter Eichhubl, Michael Fisher, L. Y. Murai, Monterey Bay Aquarium Research Institute (MBARI), Monterey Bay Aquarium Research Institute, Moss Landing Marine Laboratories, 8272 Moss Landing Road, Applied Fluids Engineering, Inc., AOA Geophysics, inc., United States Geological Survey [Reston] (USGS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, and EGU, Publication
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, Fault scarp, 01 natural sciences, lcsh:TD1-1066, Head (geology), Bathymetry, 14. Life underwater, lcsh:Environmental technology. Sanitary engineering, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geomorphology, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Colluvium, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:GE1-350, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QE1-996.5, lcsh:Geography. Anthropology. Recreation, Landslide, Debris, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment, Seafloor spreading, lcsh:Geology, lcsh:G, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, General Earth and Planetary Sciences, Seismology, Geology, Submarine landslide
Abstract: International audience; Recent investigations using the Monterey Bay Aquarium Research Institutes (MBARI) Remotely Operated Vehicles (ROVs) "Ventana" and "Tiburon" and interpretation of MBARI's EM 300 30 kHz multibeam bathymetric data show that the northern flank of the Santa Barbara Basin has experienced massive slope failures. Of particular concern is the large (130 km2) Goleta landslide complex located off Coal Oil Point near the town of Goleta, that measures 14.6-km long extending from a depth of 90 m to nearly 574 m deep and is 10.5 km wide. We estimate that approximately 1.75 km3 has been displaced by this slide during the Holocene. This feature is a complex compound submarine landslide that contains both surfical slump blocks and mud flows in three distinct segments. Each segment is composed of a distinct head scarp, down-dropped head block and a slide debris lobe. The debris lobes exhibit hummocky topography in the central areas that appear to result from compression during down slope movement. The toes of the western and eastern lobes are well defined in the multibeam image, whereas the toe of the central lobe is less distinct. Continuous seismic reflection profiles show that many buried slide debris lobes exist and comparison of the deformed reflectors with ODP Drill Site 149, Hole 893 suggest that at least 200 000 years of failure have occurred in the area (Fisher et al., 2005a). Based on our interpretation of the multibeam bathymetry and seismic reflection profiles we modeled the potential tsunami that may have been produced from one of the three surfical lobes of the Goleta slide. This model shows that a 10 m high wave could have run ashore along the cliffs of the Goleta shoreline. Several other smaller (2 km2 and 4 km2) slides are located on the northern flank of the Santa Barbara Basin, both to the west and east of Goleta slide and on the Conception fan along the western flank of the basin. One slide, named the Gaviota slide, is 3.8 km2, 2.6 km long and 1.7 km wide. A distinct narrow scar extends from near the eastern head wall of this slide for over 2km eastward toward the Goleta slide and may represent either an incipient failure or a remnant of a previous failure. Push cores collected within the main head scar of this slide consisted of hydrogen sulfide bearing mud, possibly suggesting active fluid seepage and a vibra-core penetrated ~50 cm of recent sediment overlying colluvium or landslide debris confirming the age of ~300 years as proposed by Lee et al. (2004). However, no seeps or indications of recent movement were observed during our ROV investigation within this narrow head scar indicating that seafloor in the scar is draped with mud.
Published: 2006
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28. Multi-objective calibration of a surface water-groundwater flow model in an irrigated agricultural region: Yaqui Valley, Sonora, Mexico

Author: Steven M. Gorelick, C. Lee Addams, Gerrit Schoups, EGU, Publication, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, International Research Institute for Climate Prediction (IRI), and Columbia University [New York]
Subjects: 010504 meteorology & atmospheric sciences, Groundwater flow, 0207 environmental engineering, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 02 engineering and technology, 01 natural sciences, lcsh:Technology, lcsh:TD1-1066, Water balance, Hydrology (agriculture), Evapotranspiration, Groundwater discharge, lcsh:Environmental technology. Sanitary engineering, 020701 environmental engineering, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:Environmental sciences, 0105 earth and related environmental sciences, Hydrology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:GE1-350, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:T, lcsh:Geography. Anthropology. Recreation, Groundwater recharge, 04 agricultural and veterinary sciences, 15. Life on land, 6. Clean water, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment, lcsh:G, 040103 agronomy & agriculture, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, Environmental science, 0401 agriculture, forestry, and fisheries, Groundwater model, Groundwater
Abstract: International audience; Multi-objective optimization was used to calibrate a regional surface water-groundwater model of the Yaqui Valley, a 6800 km2 irrigated agricultural region located along the Sea of Cortez in Sonora, Mexico. The model simulates three-dimensional groundwater flow coupled to one-dimensional surface water flow in the irrigation canals. It accounts for the spatial distribution of annual recharge from irrigation, subsurface drainage, agricultural pumping, and irrigation canal seepage. The main advantage of the calibration method is that it accounts for both parameter and model structural uncertainty. In this case, results show that the effect of including the process of bare soil evaporation is significantly greater than the effects of parameter uncertainty. Furthermore, by treating the different objectives independently, a better identification of the model parameters is achieved compared to a single-objective approach, since the various objectives are sensitive to different parameters. The simulated water balance shows that 15?20% of the water that enters the irrigation canals is lost by seepage to groundwater. The main discharge mechanisms in the Valley are crop evapotranspiration (53%), non-agricultural evapotranspiration and bare soil evaporation (19%), surface drainage to the Sea of Cortez (15%), and groundwater pumping (9%). In comparison, groundwater discharge to the estuary was relatively insignificant (less than 1%). The model was further refined by identifying zonal Kv and Kh values based on a spatial analysis of the model residuals.
Published: 2005

29. Occurrence of Zn/Al hydrotalcite in smelter-impacted soils from northern France: Evidence from EXAFS spectroscopy and chemical extractions

Author: Guillaume Morin, Thomas P. Trainor, Georges Calas, Laurence Galoisy, Marc F. Benedetti, Philippe Ildefonse, Gordon E. Brown, Farid Juillot, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
Subjects: chemistry.chemical_classification, Hydrotalcite, Extended X-ray absorption fine structure, Mineralogy, chemistry.chemical_element, Zinc, 15. Life on land, 010501 environmental sciences, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, 6. Clean water, Geophysics, Sphalerite, chemistry, Geochemistry and Petrology, Soil pH, Soil water, engineering, Organic matter, 0105 earth and related environmental sciences, Nuclear chemistry, Solid solution
Abstract: I Zinc speciation was studied by EXAFS spectroscopy, μ-SXRF elemental mapping, XRD, and chemical extraction methods in two smelter-impacted soils sampled near one of the largest Pb and Zn processing plants in Europe, which is located in northern France about 50 km south of Lille. The tilled and wooded soils chosen for study differ in Zn concentration (=600 and 1400 mg/kg, respectively), soil pH (7.5 and 5.5, respectively), and organic matter content (1.5 and 6.4 wt% TOC, respectively). In both soils, the occurrence of Fe- and Zn-rich (up to 10 wt% Zn) slag particles ranging in size from a few micrometers to a few millimeters, was shown by μ-SXRF elemental mapping of soil thin sections as well as by SEM and chemical analysis of different soil size fractions. For both soils, XRD analysis of the dense coarse fraction, which contains up to 10 wt% Zn, revealed the presence of a minor amount (1-1.5 wt%) of crystalline ZnS (sphalerite and wurtzite). In this fraction, EXAFS data show that Zn is mainly incorporated in the tetrahedral sites of a magnetite-franklinite solid solution. The clay fraction (
Published: 2003
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30. Coffinite, USiO4, Is Abundant in Nature: So Why Is It So Difficult To Synthesize?

Author: Adel Mesbah, Christophe Poinssot, Nicolas Dacheux, Christophe Den Auwer, Stéphanie Szenknect, Rodney C. Ewing, Nicolas Clavier, Janeth Lozano-Rodriguez, Interfaces de Matériaux en Evolution (LIME), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Département de recherche sur les procédés pour la mine et le recyclage du combustible (DMRC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Chimie de Nice (ICN), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)
Subjects: Abundance (chemistry), Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, 010402 general chemistry, 01 natural sciences, Inorganic Chemistry, chemistry.chemical_compound, Colloid, coffinite, [CHIM.CRIS]Chemical Sciences/Cristallography, [CHIM]Chemical Sciences, Coffinite, Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS, Mineral, Chemistry, Uranium, 021001 nanoscience & nanotechnology, Silicate, XANES, 0104 chemical sciences, EXAFS, 13. Climate action, PXRD, Yield (chemistry), Raman spectra, 0210 nano-technology, [CHIM.RADIO]Chemical Sciences/Radiochemistry, Earth (classical element)
Abstract: Coffinite, USiO4, is the second most abundant U(4+) mineral on Earth, and its formation by the alteration of the UO2 in spent nuclear fuel in a geologic repository may control the release of radionuclides to the environment. Despite its abundance in nature, the synthesis and characterization of coffinite have eluded researchers for decades. On the basis of the recent synthesis of USiO4, we can now define the experimental conditions under which coffinite is most efficiently formed. Optimal formation conditions are defined for four parameters: pH, T, heating time, and U/Si molar ratio. The adjustment of pH between 10 and 12 leads probably to the formation of a uranium(IV) hydroxo-silicate complex that acts as a precursor of uranium(IV) silicate colloids and then of coffinite. Moreover, in this pH range, the largest yield of coffinite formation (as compared with those of the two competing byproduct phases, nanometer-scale UO2 and amorphous SiO2) is obtained for 250 °C, 7 days, and 100% excess silica.
Published: 2015
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31. Density measurements and structural properties of liquid and amorphous metals under high pressure

Author: Guillaume Morard, Mathilde Roberge, Gaston Garbarino, Nicolas Guignot, Julien Siebert, Denis Andrault, Sylvain Petitgirard, A. Lincot, E. Boulard, A. Denoeud, Daniele Antonangeli, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institut des Sciences de la Terre (ISTerre), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Unité Matériaux et Transformations - UMR 8207 (UMET), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire pour l'utilisation des lasers intenses (LULI), Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geological and Environmental Sciences [Stanford] (GES), Stanford University [Stanford], Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut National de la Recherche Agronomique (INRA), Université Paris-Saclay-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut de Chimie du CNRS (INC)-Institut National de la Recherche Agronomique (INRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), and Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])
Subjects: Time delay and integration, Diffraction, Amorphous metal, Materials science, 010504 meteorology & atmospheric sciences, Analytical chemistry, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Pair distribution function, liquid and amorphous materials, 010502 geochemistry & geophysics, Condensed Matter Physics, 01 natural sciences, Diamond anvil cell, Amorphous solid, density measurements, high pressure, Data acquisition, Absorption (chemistry), 0105 earth and related environmental sciences
Abstract: International audience; We have implemented an in situ X-ray diffraction analysis method suitable for the determination of pressure-volume-temperature equations of state in the critical case of liquid and amorphous materials over an extended thermodynamic range (T > 2000K and P > 40 GPa). This method is versatile, it can be applied to data obtained using various angle-dispersive X-ray diffraction high pressure apparatus and, contrary to in situ X-ray absorption techniques, is independent from the sample geometry. Further advantage is the fast data acquisition (between 10 and 300 s integration time). Information on macroscopic bulk properties (density) and local atomic arrangement (pair distribution function g(r)) can be gathered in parallel. To illustrate the method, we present studies on liquid Fe-S alloys in the Paris Edinburgh press and in laser-heated diamond anvil cell (DAC), and measurements on Ce glass in DAC at room temperature
Published: 2014
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32. Linear spectroscopy and exciton binding energies in (Zn, Cd)Se-ZnSe heterostructures

Author: Sandrine Sanchez, Thierry Cloitre, Pierre Bigenwald, Fabio Liaci, Bernard Gil, Roger-Louis Aulombard, Rachid Essaid, Groupe d'étude des semiconducteurs (GES), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), Avignon Université (AU), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, and Stanford University-Stanford University
Subjects: Photoluminescence, Materials science, Condensed Matter::Other, Mechanical Engineering, Exciton, Context (language use), Heterojunction, 02 engineering and technology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Molecular physics, Condensed Matter::Materials Science, Mechanics of Materials, Excited state, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Atomic physics, 010306 general physics, 0210 nano-technology, Electronic band structure, Spectroscopy, Quantum well
Abstract: International audience; We report here on the study of the optical properties of ZnCdSe-ZnSe quantum structures elaborated by metal-organic chemical vapour deposition on GaAs substrates. The band structure of these samples is experimentally investigated by means of photoluminescence and photoreflectance spectroscopy. This makes clear the relationship between strain, carrier confinement and excitonic effects. We have computed for the first time heavy- and light-hole excitons associated with ground and excited states sub-bands, in the context of a self-consistent two-parameter trial function.
Published: 1997
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33. A 100-year long record of alkenone-derived SST changes by Southeast Greenland

Author: Mads Hvid Ribergaard, Jerry M. Lloyd, Antoon Kuijpers, Marie-Alexandrine Sicre, Torben Schmith, Fiammetta Straneo, David A. Sutherland, Camilla S. Andresen, Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Geological Survey of Denmark and Greenland (GEUS), Paléocéanographie (PALEOCEAN), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Woods Hole Oceanographic Institution (WHOI), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, University of Oregon [Eugene], Durham University, NAIV project supported by LEFE program of the Institut National des Sciences de l'Univers (INSU) of the Centre national de la Recherche Scientifique, Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Alkenone, 010504 meteorology & atmospheric sciences, Fjord, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Aquatic Science, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Hydrographic survey, 14. Life underwater, Glacial period, Subsurface flow, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Advection, Geology, Glacier, Sea surface temperature, 13. Climate action, Climatology
Abstract: International audience; Sediment core ER07 from Sermilik Fjord by Helheim Glacier in Southeast Greenland was analysedfor alkenones to document sea surface temperature (SST) changes over the past 100 years. Thealkenone SST values, ranging from 8 to 12°C, contrasts with colder values (0-4°C) obtained fromrecent hydrographic surveys inside the fjord. We suggest that advection of allochtonous alkenonesproduced in the warm Irminger Current waters circulating on the shelf likely accounts for thisdifference. The temperature range of the alkenone-derived record is similar to in situ observationsof 8-11°C on the shelf just outside Sermilik Fjord, and its variability over the past 100 yearsresembles the constructed variability over the shelf using remote instrumental data. This suggeststhat oceanographic changes on the adjacent shelf are linked to regional changes of the IrmingerCurrent and the East Greenland Current. The subsurface water heat content has previously beensuggested as an important control on Greenland outlet glacier stability and underlined by an episodeof warm subsurface waters ~ 1940 concurrent with markedly increased calving and retreat ofHelheim Glacier. Our results therefore suggest that alkenone-derived SST time series from highsedimentation rate glacial fjords may provide a new approach for reconstruction of past changes ofshelf water properties and variability around Greenland.
Published: 2013
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34. Experimental investigation of the stability of Fe-rich carbonates in the lower mantle

Author: Boulard, E., Menguy, N., Auzende, Anne-Line, Benzerara, K., Bureau, H., Antonangeli, D., Corgne, A., Morard, Guillaume, Siebert, J., Perrillat, Jean-Philippe, Guyot, F., Fiquet, G., Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Terre et Planètes, European Synchrotron Radiation Facility (ESRF)-Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), European Project, Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF)-Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: BEARING ECLOGITE, 20 GPA, X-RAY-DIFFRACTION, PHASE-RELATIONS, MAGNESITE, HIGH-PRESSURE, EARTHS LOWER MANTLE, DEEP MANTLE, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, CRYSTAL-STRUCTURE, EQUATION-OF-STATE
Abstract: International audience; The fate of carbonates in the Earth's mantle plays a key role in the geodynamical carbon cycle. Although iron is a major component of the Earth's lower mantle, the stability of Fe-bearing carbonates has rarely been studied. Here we present experimental results on the stability of Fe-rich carbonates at pressures ranging from 40 to 105 GPa and temperatures of 1450-3600 K, corresponding to depths within the Earth's lower mantle of about 1000-2400 km. Samples of iron oxides and iron-magnesium oxides were loaded into CO2 gas and laser heated in a diamond-anvil cell. The nature of crystalline run products was determined in situ by X-ray diffraction, and the recovered samples were studied by analytical transmission electron microscopy and scanning transmission X-ray microscopy. We show that Fe-(II) is systematically involved in redox reactions with CO2 yielding to Fe-(III)-bearing phases and diamonds. We also report a new Fe-(III)-bearing high-pressure phase resulting from the transformation of FeCO3 at pressures exceeding 40 GPa. The presence of both diamonds and an oxidized C-bearing phase suggests that oxidized and reduced forms of carbon might coexist in the deep mantle. Finally, the observed reactions potentially provide a new mechanism for diamond formation at great depth.
Published: 2012
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35. Morphological preservation of carbonaceous plant fossils in blueschist metamorphic rocks fromNew Zealand

Author: E. Galvez, M., Beyssac, O., Benzerara, K., Bernard, Serge, Menguy, N., C. Cox, S., Martinez, I., R. Johnston, M., E. Brown Jr, G., Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Minéralogie et Cosmochimie du Muséum (LMCM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Dunedin Research Centre, GNS Science, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDV.OT]Life Sciences [q-bio]/Other [q-bio.OT]
Abstract: International audience; Morphological and chemical evidence of ancient life is widespread in sedimentary rocks retrieved from shallow depths in the Earth's crust. Metamorphism is highly detrimental to the preservation of biological information in rocks, thus limiting the geological record in which traces of life might be found. Deformation and increasing pressure ⁄ temperature during deep burial may alter the morphology as well as the composition and structure of both the organic and mineral constituents of fossils. However, microspore fossils have been previously observed in intensely metamorphosed rocks. It has been suggested that their small size, and ⁄ or the nature of the polymer composing their wall, and ⁄ or the mineralogy of their surrounding matrix were key parameters explaining their exceptional preservation. Here, we describe the remarkable morphological preservation of plant macrofossils in blueschist metamorphic rocks from New Zealand containing lawsonite. Leaves and stems can be easily identified at the macroscale. At the microscale, polygonal structures with walls mineralized by micas within the leaf midribs and blades may derive from the original cellular ultrastructure or, alternatively, from the shrinkage during burial of the gelified remnants of the leaves in an abiotic process. Processes and important parameters involved in the remarkable preservation of these fossils during metamorphism are discussed. Despite the excellent morphological preservation, the initial biological polymers have been completely transformed to graphitic carbonaceous matter down to the nanometer scale. This occurrence demonstrates that plant macrofossils may experience major geodynamic processes such as metamorphism and exhumation involving deep changes and homogenization of their carbon chemistry and structure but still retain their morphology with remarkable integrity even if they are not shielded by any hard-mineralized concretion
Published: 2012
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36. Mineral-Aqueous Solution Interfaces and Their Impact on the Environment

Author: Georges Calas, Gordon E. Brown, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), and Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)
Subjects: Chemical process, Chemistry, Geology, Nanotechnology, Context (language use), Natural environment, Weathering, 02 engineering and technology, 010502 geochemistry & geophysics, 021001 nanoscience & nanotechnology, 01 natural sciences, Ferrihydrite, Isotope fractionation, Lead (geology), 13. Climate action, Geochemistry and Petrology, Environmental Chemistry, 0210 nano-technology, Dissolution, 0105 earth and related environmental sciences, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience; This Perspective describes an area of geochemistry that involves minerals, their surfaces, and the interactions of these surfaces with water and the ions and molecules present in water, some of which, like arsenic, are highly toxic to organisms. The importance of these interactions, together with those between microorganisms and mineral surfaces, cannot be overestimated, for they control the composition of our natural environment and mitigate some of the anthropogenic perturbations that are changing our environment in ways that are often unpredictable and sometimes detrimental. Following overviews of our scientific careers to date, including acknowledgments of our former and current students and research collaborators, we highlight some of the scientific contributions of Victor Goldschmidt, Irving Langmuir, Linus Pauling, Konrad Krauskopf, Werner Stumm, and others that led directly or indirectly to the evolution of this field, recalling personal interactions with some of these pioneers. In all fields of science, advances are made when new experimental methods, new characterisation and computational tools, and new theories become available. The field of mineralwater interface geochemistry is no different and has advanced significantly over the past 30-40 years due to enormous changes in molecular-level experimental methods, particularly those involving the extremely intense X-ray sources known as synchrotrons, in digital computers, and in molecular-level theories. We (GB and GC) offer our perspectives on the development of synchrotron radiation sources and their applications to mineral-water interface processes, based on our personal experiences starting in the early days of these major user facilities. We discuss some of these new methods and theories and their applications to mineral-water interface processes through various examples. Because of the complexity of mineral-water interfaces, particularly in natural Earth surface environments, where natural organic matter and microorganisms play very important roles, we adopt a reductionist approach and consider simple model systems of increasing complexity in our quest to understand the chemical processes occurring at these interfaces at the molecular level. We start with a discussion of the acid-base chemistry of metal-oxide surfaces in contact with bulk water and empirical models of the electrical double layer (EDL) that is thought to develop at solid-water interfaces. We then consider experimental and theoretical studies of the EDL, which show that the classical Helmholtz-Gouy- Chapman-Stern-Grahame model is qualitatively correct. Following a story about some of the new, controversial research on the structure of water, we discuss (1) experimental and theoretical studies of the reaction of water with metal-oxide surfaces, (2) the structure of hydrated mineral surfaces, (3) the uptake of cations and anions on metal-oxide surfaces, (4) X-ray absorption spectroscopy studies of lead and arsenic adsorption complexes at mineral-water interfaces, (5) the adsorption of organic molecules at mineral-water interfaces, (6) the effect of organic and microbial biofilm coatings on the reactivity of mineral surfaces, and (7) the effect of particle size on the structure and properties of nanoparticles, using ferrihydrite as an example of a natural nanomineral and silver nanoparticles as an example of an engineered nanoparticle. In keeping with the spirit of Geochemical Perspectives, we interspersed personal experiences resulting from our involvement in most of these research areas. To put the results of this more basic research in context we end by discussing selected applications of mineral-water interface geochemistry to environmental and Earth science problems, including (1) sorption reactions in real environmental systems that were anthropogenically perturbed, focusing on lead-polluted sites in the USA and France and As-polluted areas in southern Asia and France, (2) dissolution and weathering mechanisms of silicate minerals and zircon, (3) the interaction of aluminum with diatom surfaces, (4) the interaction of cobalt with manganese oxides, (5) the role of mineral-surface reactions in isotope fractionation, (6) the role of mineral surfaces in mineral- carbonation reactions, and (7) the surface chemistry associated with alteration of nuclear waste glasses. We finish with our thoughts on what has and has not been learned about mineral-water interface processes over the past 30 years and offer our opinions about some of the exciting research opportunities in this field that await the next generation of geochemists
Published: 2012
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37. Ni speciation in a New Caledonian lateritic regolith : a quantitative X-ray absorption spectroscopy investigation

Author: Emmanuel Fritsch, Georges Ona-Nguema, Dik Fandeur, Guillaume Morin, Gabrielle Dublet, Farid Juillot, Gordon E. Brown, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, and Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Goethite, Olivine, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Mineralogy, Weathering, 010501 environmental sciences, Saprolite, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Regolith, Geochemistry and Petrology, Ultramafic rock, visual_art, Silicate minerals, visual_art.visual_art_medium, Laterite, engineering, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Changes in Ni speciation in a 64 m vertical profile of a New Caledonian saprolitic-lateritic regolith developed over ultramafic rocks under tropical weathering conditions were investigated by EXAFS spectroscopy. Quantitative analysis of the EXAFS spectra by linear combination-least squares fitting (LC-LSF) using a large set of model compound spectra showed that Ni hosted in primary silicate minerals (olivine and serpentine) in the bedrock is incorporated in secondary phyllosilicates (serpentine) and Fe-oxides (goethite) in the saprolite unit and mainly in goethite in the laterite unit. A significant concentration of Ni (up to 30% of total Ni) is also hosted by Mn-oxides in the transition laterite (i.e. the lowest part of the laterite unit which contains large amounts of Mn-oxides). However, the amount of Ni associated with Mn-oxides does not exceed 20% of the total Ni in the overlying laterite unit. This sequence of Ni species from bedrock to laterite yields information about the behavior of Ni during tropical weathering of ultramafic rocks. The different Ni distributions in phyllosilicates in the bedrock (randomly distributed) and in the saprolite unit (clustered) indicate two generations of Ni-bearing phyllosilicates. The first, which formed at higher temperature, is related to serpentinization of oceanic crust, whereas the second one, which formed at lower temperature, is associated with post-obduction weathering of ultramafic rocks. In addition, the observed decrease in the proportion of Ni hosted by Mn-oxides from the transition laterite to the upper lateritic horizons indicates dissolution of Mn-oxides during the last stages of differentiation of the lateritic regolith (i.e. lateritization). Finally, the ubiquitous occurrence of Ni-bearing goethite emphasizes the major role of this phase in Ni speciation at the different weathering stages and suggests that goethite represents the major host for Ni in the final tropical weathering stages of New Caledonian ultramafic rocks.
Published: 2012
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38. Late Jurassic magmatism, metamorphism, and deformation in the Blue Mountains Province, northeast Oregon

Author: Arthur W. Snoke, Joshua J. Schwartz, Joseph L. Wooden, Kenneth Johnson, Fabrice Cordey, Carol D. Frost, Calvin G. Barnes, Todd A. LaMaskin, Laboratoire de mécanique des sols, structures et matériaux (MSSMat), CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Department of Geological Sciences, University of Alabama [Tuscaloosa] (UA), Department of Geology and Geophysics [Laramie], University of Wyoming (UW), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Natural Sciences, University of Houston, Department of Geosciences, Texas Tech University [Lubbock] (TTU), University of Oregon [Eugene], Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, University of Wyoming University of Alabama University of Alabama Research Grants Committee (RGC) National Science Foundation (NSF) : EAR-0911681, EAR-0711470, EAR-073243, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Metamorphic rock, Metamorphism, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, IGNEOUS ROCKS, Thrust fault, CENTRAL BRITISH-COLUMBIA, GEOCHEMICAL CLASSIFICATION, TECTONIC EVOLUTION, Geomorphology, CACHE CREEK TERRANE, WESTERN SIERRA-NEVADA, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Terrane, geography, AMERICAN CORDILLERA, geography.geographical_feature_category, EASTERN OREGON, Geology, Orogeny, 15. Life on land, CANADIAN CORDILLERA, Igneous rock, Ridge, Sedimentary rock, CENTRAL KLAMATH MOUNTAINS
Abstract: International audience; An early to mid-Mesozoic record of sedimentation, magmatism, and metamorphism is well developed in the Blue Mountains Province of northeast Oregon. Detailed studies-both north and south of the Blue Mountains Province (e. g., terranes of the Intermontane belt, Klamath Mountains, and western Sierra Nevada) have documented a complex Middle to Late Jurassic orogenic evolution. However, the timing of magmatic, metamorphic, and deformational events in the Blue Mountains, and the significance of these events in relationship to other terranes in the western North American Cordillera remain-poorly understood. In this study, we investigate the structural, magmatic, and metamorphic histories of brittle to semibrittle deformation zones that indicate widespread Late Jurassic orogenesis in the Blue Mountains Province. Folding and faulting associated with contractional deformation are primarily localized along terrane boundaries (e. g., Baker-Wallowa and Baker-Izee-Olds Ferry boundaries) and within the composite Baker oceanic melange terrane (e. g., Bourne-Greenhorn subterrane boundary). These brittle to semibrittle deformation zones are broadly characterized by the development of E-W-oriented slaty to spaced cleavage in fine-grained metasedimentary rocks of the Baker terrane (e. g., Elkhorn Ridge Argillite), approximately N-S-bivergent folding, and N- and S-dipping reverse and thrust faulting on opposite flanks of the Baker terrane. Similarly oriented contractional features are also present in late Middle Triassic to early Late Jurassic (i.e., Oxfordian Stage, ca. 159 Ma) sedimentary rocks of the John Day and Huntington areas of northeast Oregon. Radiometric age constraints from youngest detrital zircons in deformed sedimentary rocks and crystallization ages of postkinematic plutons, which intrude the deformation zones, limit deformation to between ca. 159 and ca. 154 Ma. We suggest that the widespread, approximately N-S-directed contractional features in the Blue Mountains Province record a short-lived, intense early Late Jurassic deformational event and preserve an example of upper-crustal strain localization associated with terminal arc-arc collision between the Olds Ferry and Wallowa island-arc terranes. The age interval of deformation in the Blue Mountains Province is younger than Middle Jurassic deformation in the Canadian Cordillera and Klamath Mountains (Siskiyou orogeny) and predates classic Nevadan orogenesis
Published: 2011
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39. Constraints on the late Quaternary glaciations in Tibet from cosmogenic exposure ages of moraine surfaces

Author: Frederick J. Ryerson, Paul Tapponnier, Jérôme Van der Woerd, Marie-Luce Chevalier, Xiaohan Liu, Robert C. Finkel, Haibing Li, Jing Liu-Zeng, George E. Hilley, Institute of Geology [CAGS Beijing] (CAGS), Chinese Academy of Geological Sciences [Beijing] (CAGS), Ministry of Land and Resources (MLR)-Ministry of Land and Resources (MLR), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Earth Observatory of Singapore (EOS), Nanyang Technological University [Singapour], Sismologie (IPGS) (IPGS-Sismologie), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institute of Tibetan Plateau Research (ITPR), Chinese Academy of Sciences [Changchun Branch] (CAS), Department of Earth and Planetary Science [UC Berkeley] (EPS), University of California [Berkeley], University of California-University of California, and Lawrence Livermore National Laboratory (LLNL)
Subjects: Archeology, China, 010504 meteorology & atmospheric sciences, Range (biology), [SDE.MCG]Environmental Sciences/Global Changes, 010502 geochemistry & geophysics, Tibet, 01 natural sciences, Paleontology, Quaternary glaciation, Paleoclimatology, paleoclimate, Glacial period, Precipitation, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Global and Planetary Change, geography, geography.geographical_feature_category, Feature (archaeology), Geology, 15. Life on land, moraine, 10Be cosmogenic nuclide dating, 13. Climate action, Moraine, Erosion, Quaternary
Abstract: International audience; This contribution provides new constraints on the timing of Tibetan glacial recessions recorded by the abandonment of moraines. We present cosmogenic radionuclide 10Be inventories at 17 sites in southern and western Tibet (32 crests, 249 samples) and infer the range of permissible emplacement ages based on these analyses. Individual large embedded rock and boulder samples were collected from the crests of moraine surfaces and analyzed for 10Be abundance. We consider two scenarios to interpret the age of glacial recession leading to the moraine surface formation from these sample exposure ages: 1) Erosion of the moraine surface is insignificant and so the emplacement age of the moraines is reflected by the mean sample age; and 2) Erosion progressively exposes large boulders with little prior exposure, and so the oldest sample age records the minimum moraine emplacement age. We found that depending on the scenario chosen, the moraine emplacement age can vary by > 50% for 100 ka-old samples. We consider two scaling models for estimating the production rates of 10Be in Tibet, which has an important, although lesser, effect on inferred moraine ages. While the data presented herein effectively increase the database of sample exposure ages from Tibet by 20%, we find that uncertainties related to the interpretation of the 10Be abundance within individual samples in terms of moraine emplacement ages are sufficient to accommodate either a view in which glacial advances are associated with temperature minima or precipitation maxima that are recorded by independent paleoclimate proxies. A reanalysis of published data from moraines throughout Tibet shows that the variation we observe is not unique to our dataset but rather is a robust feature of the Tibetan moraine age database. Thus, when viewed in a similar way with other samples collected from this area, uncertainties within moraine exposure ages obscure attribution of Tibetan glacial advances to temperature minima or precipitation maxima. Our work suggests that more reliable chronologies of Tibetan glaciations will come from improvements in production rate models for this portion of the world, as well as a better understanding of the processes that form and modify these geomorphic surfaces.
Published: 2011
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40. Using radium isotopes to characterize water ages and coastal mixing rates: A sensitivity analysis

Author: Knee, K. L., Garcia-Solsona, E., Garcia-Orellana, J., Boehm, A. B., Paytan, A., Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Ciencia i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona (UAB), Environmental and Water Studies, Stanford University, Institute of Marine Sciences, University of California [Santa Cruz] (UCSC), University of California-University of California, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), University of California [Santa Cruz] (UC Santa Cruz), and University of California (UC)-University of California (UC)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, SUBMARINE GROUNDWATER DISCHARGE, GROUNDWATER, RESIDENCE TIME, NUTRIENT DISCHARGE, DIAGRAMS, SURF ZONE, FECAL, DIFFUSION, INDICATOR BACTERIA, NEW-YORK, NATURAL GEOCHEMICAL TRACERS, CONTAMINATED, SUBTERRANEAN ESTUARY
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W., 2006, PAPERS SUMMER UNDERG, P51 Taniguchi M, 2003, BIOGEOCHEMISTRY, V66, P35, DOI 10.1023/B:BIOG.0000006090.25949.8d Taylor J. R., 1997, INTRO ERROR ANAL, P160 Turner IL, 1997, J COASTAL RES, V13, P46 Weinstein Y., 2006, RADIOACT ENV, V8, P360, DOI DOI 10.1016/S1569-4860(05)08029-0 Windom HL, 2006, MAR CHEM, V102, P252, DOI 10.1016/j.marchem.2006.06.016 Knee, Karen L. Garcia-Solsona, Ester Garcia-Orellana, Jordi Boehm, Alexandria B. Paytan, Adina 4 AMER SOC LIMNOLOGY OCEANOGRAPHY WACO LIMNOL OCEANOGR-METH; Numerous studies have used naturally occurring Ra isotopes (Ra-223, Ra-224, Ra-226, and Ra-228, with half-lives of 11.4 d, 3.7 d, 1600 y, and 5.8 y, respectively) to quantify water mass ages, coastal ocean mixing rates, and submarine groundwater discharge (SGD). Using Monte Carlo models, this study investigated how uncertainties in Ra isotope activities and the derived activity ratios (AR) arising from analytical uncertainty and natural variability affect the uncertainty associated with Ra-derived water ages and eddy diffusion coefficients, both of which can be used to calculate SGD. Analytical uncertainties associated with Ra-224, Ra-226, and Ra-228 activities were reported in most published studies to be less than 10% of sample activity; those reported for Ra-223 ranged from 7% to 40%. Relative uncertainty related to natural variability-estimated from the variability in Ra-223 and Ra-224 activities of replicate field samples-ranged from 15% to 50% and was similar for Ra-223 activity, Ra-224 activity, and the Ra-224/Ra-223 AR. Our analysis revealed that AR-based water ages shorter than 3-5 d often have relative uncertainties greater than 100%, potentially limiting their utility. Uncertainties in eddy diffusion coefficients estimated based on cross-shore gradients in short-lived Ra isotope activity were greater when fewer points were used to determine the linear trend, when the coefficient of determination (R-2) was low, and when Ra-224, rather than Ra-223, was used. By exploring the uncertainties associated with Ra-derived water ages and eddy diffusion coefficients, this study will enable researchers to apply these methods more effectively and to reduce uncertainty.
Published: 2011
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41. Heavy metal association with Particulate Organic Matter in contaminated agrosystems

Author: Labanowski, Jérôme, van Hullebusch, Eric, Farges, Francois, Harfouche, Messaoud, Borca, Camelia, Foy, Eddy, Lamy, Isabelle, van Oort, Folkert, Laboratoire de Chimie et Microbiologie de l'Eau (LCME), Université de Poitiers-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Marne-la-Vallée (UPEM), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, IPS, Institut Paul Scherrer - Swiss Light Source, Villigen, Suisse, Partenaires INRAE, Service Interdisciplinaire sur les Systèmes Moléculaires et les Matériaux (ex SCM) (SIS2M UMR 3299), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Science du Sol (USS), Institut National de la Recherche Agronomique (INRA), Laboratoire de Chimie de l'Eau et de l'Environnement (LCEE), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Stanford University, Institut Paul Scherrer (IPS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), ProdInra, Migration, and Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC)
Subjects: [SDV] Life Sciences [q-bio], [SDE] Environmental Sciences, [SDV]Life Sciences [q-bio], [SDE]Environmental Sciences, [SDE.ES] Environmental Sciences/Environmental and Society, [SDE.ES]Environmental Sciences/Environmental and Society, ComputingMilieux_MISCELLANEOUS
Abstract: National audience
Published: 2009

42. EXAFS and HRTEM Evidence for As(III)-Containing Surface Precipitates on Nanocrystalline Magnetite: Implications for As Sequestration

Author: Morin, Guillaume, Wang, Yuheng, Ona-Nguema, Georges, Juillot, Farid, Calas, Guillaume, Menguy, N., Aubry, Emmanuel, R. Bargar, John, E. Brown Jr, Gordon, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Biogéochimie et écologie des milieux continentaux (Bioemco), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Stanford Synchrotron Radiation Laboratory (SSRL), Stanford Linear Accelerator Center, Department of Geological and Environmental Sciences [Stanford] (GES), Stanford University [Stanford], and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
Subjects: [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry
Abstract: International audience; Arsenic sorption onto iron oxide spinels such as magnetite could contribute to immobilization of arsenite (AsO3 3-), the reduced, highly toxic form of arsenic in contaminated anoxic groundwaters, as well as to putative remediation processes. Nanocrystalline magnetite (10 μmol/m2). However, the higher solubility of the amorphous surface precipitate compared to the 3C surface complexes causes a dramatic increase of dissolved As concentration for coverages above 1.9 μmol/m2.
Published: 2009

43. Scanning fransmission X-ray microscopy analysis of metamorphic biogenic carbon

Author: Bernard, S., Benzerara, K., Beyssac, O., Brown Jr, G.E., Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: ComputingMilieux_MISCELLANEOUS, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience
Published: 2008
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44. Arsenite sorption at the magnetite–water interface during aqueous precipitation of magnetite: EXAFS evidence fo ra new arsenite surface complex

Author: Farid Juillot, Nicolas Menguy, Georges Calas, Gordon E. Brown, François Guyot, Georges Ona-Nguema, Yuheng Wang, Guillaume Morin, Emmanuel Aubry, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Surface and Aqueous Geochemistry Group [Stanford], Advanced Light Source [LBNL Berkeley] (ALS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University-SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Stanford Synchrotron Radiation Lightsource (SSRL SLAC), Department of Geological and Environmental Sciences [Stanford] (GES), Stanford University [Stanford], Stanford Synchrotron Radiation Laboratory (SSRL), Stanford Linear Accelerator Center, Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Stanford University-Stanford University-Advanced Light Source [LBNL Berkeley] (ALS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Geological Sciences [Stanford] (GS), and Stanford EARTH
Subjects: Aqueous solution, Precipitation (chemistry), Inorganic chemistry, chemistry.chemical_element, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Sorption, 010501 environmental sciences, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Adsorption, chemistry, 13. Climate action, Geochemistry and Petrology, Solubility, Arsenic, 0105 earth and related environmental sciences, Arsenite, Magnetite, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: The interaction of aqueous As(III) with magnetite during its precipitation from aqueous solution at neutral pH has been studied as a function of initial As/Fe ratio. Arsenite is sequestered via surface adsorption and surface precipitation reactions, which in turn influence the crystal growth of magnetite. Sorption samples were characterized using EXAFS spectroscopy at the As K-edge in combination with HRTEM observations, energy dispersive X-ray analysis at the nanoscale, electron energy loss spectroscopy at the Fe L3-edge, and XRD-Rietveld analyses of reaction products. Our results show that As(III) forms predominantly tridentate hexanuclear As(III)O3 complexes ( 3 C), where the As(III)O3 pyramids occupy vacant tetrahedral sites on {1 1 1} surfaces of magnetite particles. This is the first time such a tridentate surface complex has been observed for arsenic. This complex, with a dominant As–Fe distance of 3.53 ± 0.02 A ˚ , occurs in all samples examined except the one with the highest As/Fe ratio (0.33). In addition, at the two highest As/Fe ratios (0.133 and 0.333) arsenite tends to form mononuclear edge-sharing As(III)O3 species ( 2 E) within a highly soluble amorphous As(III)–Fe(III,II)-containing precipitate. At the two lowest As/Fe ratios (0.007 and 0.033), our results indicate the presence of additional As(III) species with a dominant As–Fe distance of 3.30 ± 0.02 A ˚ , for which a possible structural model is proposed. The tridentate 3 C As(III)O3 complexes on the {1 1 1} magnetite surface, together with this additional As(III) species, dramatically lower the solubility of arsenite in the anoxic model systems studied. They may thus play an important role in lowering arsenite solubility in putative magnetite-based water treatment processes, as well as in natural iron-rich anoxic media, especially during the reductive dissolution-precipitation of iron minerals in anoxic environments. 2008 Elsevier Ltd. All rights reserved.
Published: 2008
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45. Reconstruction of seasonal temperature variability in the tropical Pacific Ocean from the shell of the scallop, Comptopallium radula

Author: Laurent Chauvaud, Robert B. Dunbar, Julien Thébault, Jacques Clavier, Jennifer Guarini, Renaud Fichez, Eric Morize, David A. Mucciarone, Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Brest ( UBO ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Institut Universitaire Européen de la Mer ( IUEM ), Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ), CAMELIA - Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques, Observatoire océanologique de Banyuls ( OOB ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Department of Geological and Environmental Sciences [Stanford] ( GES ), Stanford University [Stanford], Centre d'océanologie de Marseille ( COM ), Centre National de la Recherche Scientifique ( CNRS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de la Méditerranée - Aix-Marseille 2, This work was supported by IRD, the Programme National Environnement Côtier (PNEC) and the ACIPECTEN. It was part of a 3-year research program funded by IRD and the Région Bretagne., Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, Centre d'océanologie de Marseille (COM), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de la Méditerranée - Aix-Marseille 2
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Temperature salinity diagrams, Mineralogy, 010502 geochemistry & geophysics, 01 natural sciences, Isotopes of oxygen, [ SDE ] Environmental Sciences, chemistry.chemical_compound, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, 14. Life underwater, Precipitation, Transect, Mollusca, 0105 earth and related environmental sciences, Calcite, biology, Pectinidae, biology.organism_classification, [ SDU.STU.GC ] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [ SDE.MCG ] Environmental Sciences/Global Changes, Oceanography, chemistry, Scallop, [SDE]Environmental Sciences, Geology
Abstract: International audience; We investigated the oxygen isotope composition (d18O) of shell striae from juvenile Comptopallium radula (Mollusca; Pectinidae) specimens collected live in New Caledonia. Bottom-water temperature and salinity were monitored in-situ throughout the study period. External shell striae form with a 2-day periodicity in this scallop, making it possible to estimate the date of precipitation for each calcite sample collected along a growth transect. The oxygen isotope composition of shell calcite (d18Oshell calcite) measured at almost weekly resolution on calcite accreted between August 2002 and July 2003 accurately tracks bottom-water temperatures. A new empirical paleotemperature equation for this scallop species relates temperature and d18Oshell calcite: t(°C)=20.00(+/-0.61)-3.66(+/-0.39)x(d18Oshell calcite VPDB -d18Owater VSMOW) The mean absolute accuracy of temperature estimated using this equation is 1.0 °C at temperatures between 20 and 30 °C. Uncertainties regarding the precise timing of CaCO3 deposition and the actual variations in d18Owater at our study sites probably contribute to this error. Comparison with a previously published empirical paleotemperature equation indicates that C. radula calcite is enriched in 18O by ~0.7‰ relative to equilibrium. Given the direction of this offset and the lack of correlation between shell growth rate and d18Oshell calcite, this disequilibrium is unlikely to be related to kinetic isotope effects. We suggest that this enrichment reflects (1) a relatively low pH in the scallop's marginal extrapallial fluid (EPF), (2) an isotopic signature of the EPF different from that of seawater, or (3) Rayleigh fractionation during the biocalcification process. Relative changes in d18Oshell calcite reflect seawater temperature variability at this location and we suggest that the shell of C. radula may be useful as an archive of past seawater temperatures.
Published: 2007
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46. Exceptional preservation of fossil plant spores in high-pressure metamorphic rocks

Author: Karim Benzerara, Gordon E. Brown, François Guyot, Bruno Goffé, Sylvain Bernard, Nicolas Menguy, Olivier Beyssac, Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de minéralogie, cristallographie de Paris (LMCP), Surface and Aqueous Geochemistry Group [Stanford], Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University-SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University-Advanced Light Source [LBNL Berkeley] (ALS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Stanford University-Stanford University, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Advanced Light Source [LBNL Berkeley] (ALS), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Lawrence Berkeley National Laboratory [Berkeley] (LBNL)-Stanford Synchrotron Radiation Lightsource (SSRL SLAC)
Subjects: 010506 paleontology, HRTEM, Metamorphic rock, Geochemistry, Metamorphism, carbonates, 010502 geochemistry & geophysics, 01 natural sciences, biosignature, Paleontology, chemistry.chemical_compound, Geochemistry and Petrology, Biosignature, Earth and Planetary Sciences (miscellaneous), Alpine orogeny, Ankerite, Raman, 0105 earth and related environmental sciences, Magnetite, Calcite, fossil, organic carbon, STXM, Diagenesis, Geophysics, chemistry, 13. Climate action, Space and Planetary Science, metamorphism, Geology, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience; It is commonly believed that high-grade metamorphism erases all traces of fossils and, more generally, of biogenicity in rocks. To address this issue, we report in this study X-ray spectromicroscopy, Raman microspectroscopy, and electron microscopy observations at the nm-scale of fossil lycophytes megaspores found in Triassic metasedimentary rocks from the French Alps. These rocks have undergone high-pressure metamorphic conditions (not, vert, similar 14 kbar, not, vert, similar 360 °C) during the Alpine orogeny corresponding to a burial of not, vert, similar 35 km during subduction. Despite such metamorphism, the fossil megaspores are remarkably well-preserved texturally. An unusual mineralogical zonation consisting of magnetite, ankerite and calcite is superposed on the structures of the spore walls. In parallel, chemical heterogeneities of the organic matter (OM) composing the spore walls were detected. We discuss different interpretations for our observations, in particular a scenario in which these features are remnants of the original structural heterogeneities in the spores, and provide insights on the fossilization processes under high-grade metamorphic conditions. Whatever the processes leading to such heterogeneities, our observations oppose the usual assumption that high-grade metamorphism erases all indications of biogenicity in rocks and open new avenues for investigation at the nm-scale of the evolution of organic matter during diagenesis and metamorphism.
Published: 2007
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47. The structure of silicate glasses and melts

Author: Jonathan F. Stebbins, Grant S. Henderson, Georges Calas, Department of Geology, University of Toronto, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
Subjects: coordination, Mineralogy, Thermodynamics, 02 engineering and technology, Neutron scattering, 010502 geochemistry & geophysics, 01 natural sciences, Molar volume, Geochemistry and Petrology, Polyamorphism, Earth and Planetary Sciences (miscellaneous), structure, heterogeneous, Spectroscopy, Silicate glass, 0105 earth and related environmental sciences, Chemistry, polyamorphism, 021001 nanoscience & nanotechnology, cations, Temperature and pressure, properties, melts, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Glass transition
Abstract: Much progress has been made in elucidating the complex structures of silicate glasses and melts. X-ray and neutron scattering, spectroscopy, and theoretical calculations now provide a reasonable clear picture of many aspects of the short-range structure of glasses (which approximates the melt structure at the glass transition temperature). Critical effects of redox conditions and volatiles on structure have been clarified. Qualitatively, links between structure and properties such as molar volume, entropy, cation partitioning, and viscosity have been established, but quantitative connections remain challenging. Effects of temperature and pressure on structure have been the subject of much recent work.
Published: 2006

48. Glasses and Melts: Linking Geochemistry and Materials Science

Author: Grant S. Henderson, Jonathan F. Stebbins, Georges Calas, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Geology, University of Toronto, Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Stanford University-Stanford University, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, 010504 meteorology & atmospheric sciences, Geochemistry, magmas, 010502 geochemistry & geophysics, 01 natural sciences, glasses, Silicate, chemistry.chemical_compound, Incomplete knowledge, volcanology, chemistry, Geochemistry and Petrology, silicate materials, Earth and Planetary Sciences (miscellaneous), [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Earth (chemistry), Silicate glass, 0105 earth and related environmental sciences, geochemistry
Abstract: Silicate melts are major components of magmatic activity and of its most spectacular expression, volcanic eruptions. The "hidden part" is even more fascinating, as silicate melts are directly involved in matter and heat transfer within the Earth and planets. Silicate glasses, often investigated as a frozen picture of their molten counterparts, are also materials of major importance in technology. Despite the difficulties in rationalizing physical and chemical properties of glasses and melts, due to an incomplete knowledge of their structure, major progress has been made recently in synthetic and natural systems. This issue of Elements reviews the properties of silicate glasses and melts from the molecular to the field scale. It includes insights into their technological applications and describes some recent advances this fast-evolving field.
Published: 2006

49. Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

Author: Klas Andersson, Bongjin Simon Mun, Karim Benzerara, Sutapa Ghosal, E. Kneedler, Satish Chandra Babu Myneni, K. Pecher, H.-Ch. Hansen, A. L. D. Kilcoyne, Hirohito Ogasawara, John R. Lawrence, Miquel Salmeron, Guido Ketteler, John C. Hemminger, D.F. Ogletree, Mary K. Gilles, Gary G. Leppard, David K. Shuh, Hendrik Bluhm, Brian P. Tonner, Tae Hyun Yoon, Tohru Araki, Adam P. Hitchcock, Tolek Tyliszczak, Anders Nilsson, James J. Dynes, Tony Warwick, Gordon E. Brown, J. Majzlam, Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Stanford Synchrotron Radiation Lightsource (SSRL SLAC), SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, FYSIKUM, Stockholm University, Stockholm University, Brockhouse Institute for Materials Research, McMaster University, McMaster University [Hamilton, Ontario], Department of Geological Sciences [Stanford] (GS), Stanford EARTH, Advanced Light Source [LBNL Berkeley] (ALS), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Irvine], University of California [Irvine] (UC Irvine), University of California (UC)-University of California (UC), Materials Science Division [LBNL Berkeley], Royal Veterinary and Agricultural University = Kongelige Veterinær- og Landbohøjskole (KVL ), FEI Company, FEI France [Merignac], National Water Research Institute, Department of Geosciences [Princeton], Princeton University, Chemical Sciences Division, Pacific Northwest National Laboratory, Pacific Northwest National Laboratory (PNNL), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of California [Irvine] (UCI), and University of California-University of California
Subjects: X-ray photoelectron spectroscopy, Photoemission spectroscopy, Analytical chemistry, 02 engineering and technology, Scanning transmission X-ray microscopy, 010402 general chemistry, 01 natural sciences, law.invention, law, Microscopy, Near-edge X-ray absorption fine structure, Physical and Theoretical Chemistry, Spectroscopy, Radiation, Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, X-ray emission spectroscopy, Atomic and Molecular Physics, and Optics, Synchrotron, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, Beamline, Water environmental science, 13. Climate action, Environmental science, 0210 nano-technology, Water vapor
Abstract: We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally relevant samples. The experiments were performed at the molecular environmental science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(1 1 1) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river water biofilms, Al-containing colloids and mineral–bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e., with water or water vapor present at ambient temperature.
Published: 2006
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50. Physics, chemistry and rheology of silicate melts and glasses

Author: Pascal Richet, Jonathan F. Stebbins, Roberto Moretti, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stanford] (GS), Stanford EARTH, and Stanford University-Stanford University
Subjects: 010302 applied physics, Polymer science, Chemistry, Geochemistry, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Geology, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Silicate, chemistry.chemical_compound, Rheology, Geochemistry and Petrology, 0103 physical sciences, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2006
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