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151. Gavialis from the Pleistocene of Thailand and Its Relevance for Drainage Connections from India to Java

Author

Komsorn Lauprasert, Wilailuck Naksri, Jeremy E. Martin, Eric Buffetaut, Julien Claude, School of Earth Sciences [Bristol], University of Bristol [Bristol], PaleoEnvironnements et PaleobioSphere (PEPS), 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), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE)

Subjects
0106 biological sciences, 010506 paleontology, Early Pleistocene, Pleistocene, Landform History, Science, [SDV]Life Sciences [q-bio], Vertebrate Paleontology, Endangered species, Fluvial, India, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDV.BID]Life Sciences [q-bio]/Biodiversity, 010603 evolutionary biology, 01 natural sciences, Genus, Animals, Paleoclimatology, Biology, Gavialis, 0105 earth and related environmental sciences, Evolutionary Biology, Alligators and Crocodiles, Multidisciplinary, biology, Ecology, Geography, Fossils, Geographical Hydrology, Paleontology, Biostratigraphy, Geomorphology, 15. Life on land, biology.organism_classification, Thailand, Biogeography, Physical Geography, Indonesia, Earth Sciences, Biological dispersal, Medicine, Mainland, Paleoecology, Paleobiology, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Research Article
Abstract

BackgroundThe genus Gavialis comprises a single living but endangered species, G. gangeticus, as well as fossil species recorded in the Miocene to Pleistocene deposits of the Indian subcontinent. The genus is also represented in the Pleistocene deposits of Java by the species G. bengawanicus, which was recently recognized to be valid. Surprisingly, no detailed report of the genus exists between these two provinces and the recent evolutionary history of Gavialis is not understood.Methodology/principal findingsWe report new material consisting of skull and mandibular remains of Gavialis from the Early Pleistocene of Khok Sung, Nakhon Ratchasima Province, northeastern Thailand. The Gavialis material described herein is attributed to Gavialis cf. bengawanicus and sheds new light on the occurrence of the genus in mainland SE Asia.Conclusions/significanceComparison of this new material with other species referred to the genus Gavialis led us to preliminary restrict the content of the genus to three species, namely G. gangeticus Gmelin, G. bengawanicus Dubois and G. lewisi Lull. The occurrence of G. cf. bengawanicus in Thailand allows us to propose a scenario for the dispersal of Gavialis from Indo-Pakistan to Indonesia, thus bridging a geographical gap between these two provinces. Dispersal by sea appears a less likely possibility than dispersal through fluvial drainages.

Published
2012

152. Iconic CO2 Time Series at Risk

Author

Frédéric Chevallier, Paul I. Palmer, Philippe Ciais, Bakr Badawy, Christian Rödenbeck, James T. Randerson, Scott Denning, Alex Vermeulen, Marc Fischer, Dylan B. A. Jones, Aslam Khalil, Thomas Röckmann, A. G. C. A. Meesters, Jing M. Chen, Martin Heimann, Andrew Schuh, Z. Poussi, Sourish Basu, Andrew R. Jacobson, G. James Collatz, Philippe Bousquet, L. Yurganov, Philippe Peylin, Maarten Krol, Prasad S. Kasibhatla, Taro Takahashi, Wouter Peters, Jorge L. Sarmiento, Andrew C. Manning, Richard Engelen, Manuel Gloor, Shamil Maksyutov, David Baker, John B. Miller, Michael J. Prather, Grégoire Broquet, Ian G. Enting, Dmitry Belikov, Sander Houweling, Marko Scholze, Jocelyn Turnbull, Prabir K. Patra, Nir Y. Krakauer, Christoph Gerbig, David S. Schimel, Parv Suntharalingam, Peter Bergamaschi, Josep G. Canadell, Annemarie Fraser, Takashi Maki, Tim Butler, Thomas Kaminski, Energy and Sustainability Research Institute Groni, SRON Netherlands Institute for Space Research ( SRON ), Institute for Marine and Atmospheric Research [Utrecht] ( IMAU ), Utrecht University [Utrecht], 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 ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Copenhagen Business School, Copenhagen Business School [Copenhagen] ( CBS ), Atmospheric and Oceanic Sciences Program [Princeton] ( AOS Program ), NOAA Geophysical Fluid Dynamics Laboratory ( GFDL ), National Oceanic and Atmospheric Administration ( NOAA ) -National Oceanic and Atmospheric Administration ( NOAA ) -Princeton University, School of Earth Sciences [Bristol], University of Bristol [Bristol], Amsterdam Global Change Institute, Earth and Climate, Hydrology and Geo-environmental sciences, SRON Netherlands Institute for Space Research (SRON), Institute for Marine and Atmospheric Research [Utrecht] (IMAU), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), 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), Copenhagen Business School [Copenhagen] (CBS), ICOS-ATC (ICOS-ATC), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Atmospheric and Oceanic Sciences Program [Princeton] (AOS Program), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA)-Princeton University, 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), and 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)

Subjects
carbon footprint, sea, 010504 meteorology & atmospheric sciences, Compromise, media_common.quotation_subject, Climate Change, air pollution, letter, Climate change, Commission, chemistry, 010502 geochemistry & geophysics, 01 natural sciences, carbon monoxide, biology.animal, Physical Sciences and Mathematics, Whaling, 14. Life underwater, China, fossil fuel, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, media_common, Multidisciplinary, biology, Whale, Atmosphere, methane, carbon dioxide, land use, Carbon Dioxide, Earth system science, priority journal, Economy, greenhouse gas, 13. Climate action, Greenhouse gas, [SDE]Environmental Sciences, halocarbon, aquatic environment
Abstract

COMMENTARY Common but differentiated IBI Prize Essay LETTERS I BOOKS I POLICY FORUM I EDUCATION FORUM I PERSPECTIVES LETTERS edited by Jennifer Sills Iconic CO 2 Time Series at Risk THE STEADY RISE IN ATMOSPHERIC LONG- lived greenhouse gas concentrations is the main driver of contemporary climate change. The Mauna Loa CO 2 time series (1, 2), started by C. D. Keeling in 1958 and maintained today by the Scripps Institution of Oceanography and the Earth System Research Laboratory (ESRL) of NOAA, is iconic evidence of the effect of human- caused fossil fuel and land-use change emis- sions on the atmospheric increase of CO 2 . The continuity of such records depends criti- cally on having stable funding, which is chal- lenging to maintain in the context of 3- to 4-year research grant funding cycles (3), and LEAH R. GERBER Faculty of Ecology, Evolution, and Environmental Sciences, School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA. E-mail: leah.gerber@asu.edu References 1. Associated Press, The New York Times, 6 July 2012, p. A7 (www.nytimes.com/2012/07/06/ world/europe/south-korea-whaling-plan-criticized.html). 2. S. Herman, Voice of America, 24 July 2012 (www.voanews.com/content/south-korea-still- considering-resumption-of-whaling/1444081.html). 3. L. R. Gerber, L. Morissette, K. Kaschner, D. Pauly, Science 323, 880 (2009). 4. R. Black, BBC News, 5 July 2012 (www.bbc.co.uk/news/science-environment-18719512). is currently threatened by the fi nancial crisis. The ESRL Global Monitoring Division maintains a network of about 100 surface and aircraft sites worldwide at which whole air samples are collected approximately every week for analysis of CO 2 , CH 4 , CO, halocar- bons, and many other chemical species (4). This is complemented by high-frequency measurements at the Mauna Loa, Barrow, American Samoa, and South Pole obser- vatories, and about 10 North American tall towers. The success of the NOAA program has inspired similar efforts in Europe (5), China (6), India (7), and Brazil (8), with the United Nations World Meteorological Orga- nization providing guidance and precision requirements through the Global Atmosphere Watch program (9), but no funding. 31 AUGUST 2012 Downloaded from www.sciencemag.org on August 17, 2015 AT THE RECENT INTERNATIONAL WHALING COMMISSION’S ANNUAL meeting in Panama, South Korean offi cials announced their plan to initiate a “scientifi c whaling” program (1). This announcement came as a surprise given the general sentiment that the global demand for whale meat is declining. After weeks of international outcry, on 17 July, South Korea reversed their decision to hunt whales for research, but the issue is not dead (2). South Korea claimed that the goal of the scientifi c whaling pro- gram is to study the types and amounts of fi sh whales eat, given confl ict with fi sher- ies. Yet, it is well established in the scien- tifi c literature that there are many ways to study whale diet without killing them (3). Decades of fruitless negotiation between pro- and anti-whaling nations suggests a broken system, wrought with loopholes that allow unsustainable whal- ing to continue. Within this broken system, there is no incentive to reduce whaling, as the recent announcement by South Korea shows. Whaling groups are unwilling to compromise by allowing a sustainable harvest of whales, so unsustainable (scientifi c) whaling continues. To ensure a future of both whales and whalers, we must har- ness the passion and value that people place on living whales, with- out telling people what to do or force one set of values on others. We need novel, out-of-the-box approaches to effective management and conservation of whales. We must compromise to ensure reduc- tions in whales being killed, better oversight of countries that har- vest them, and limited whaling that does not threaten the persis- tence of whales. For those who believe that whaling is unethical, I challenge you to put forward alternative ideas to a global moratorium that fosters the “loophole” of scientifi c whaling. With new plans to develop scientifi c whaling programs (4), the current global moratorium is clearly bro- ken. Scientists, conservation advocates, resource managers, and the public must work together to develop new approaches to ensure the persistence of whales in our oceans. The data collected by NOAA and its worldwide partners have been used not only to demonstrate the unassailable rise of atmo- spheric greenhouse gas concentrations, but also to infer the magnitudes, locations, and times of surface-atmosphere exchange of those gases based on small concentration gradients between sites (10). Important fi nd- ings from analysis of these records include the detection of a signifi cant terrestrial car- bon sink at northern mid-latitudes (11) and subsequent research aimed at identifying the mechanisms by which that sink must operate. Long-term, high-quality, atmospheric mea- surements are crucial for quantifying trends in greenhouse gas fl uxes and attributing them to fossil fuel emissions, changes in land-use and management, or the response of natural VOL 337 SCIENCE www.sciencemag.org Published by AAAS CREDIT: LEAH GERBER/ ARIZONA STATE UNIVERSITY The Scientifi c Whaling Loophole

Published
2012

153. Water vapor in Titan’s stratosphere from Cassini CIRS far-infrared spectra

Author

Nicholas A Teanby, Carrie M. Anderson, G. Bampasidis, Emmanuel Lellouch, F. M. Flasar, Valeria Cottini, Gordon L. Bjoraker, Richard Achterberg, N. Gorius, Patrick G. J. Irwin, R. de Kok, Bruno Bézard, Athena Coustenis, Donald E. Jennings, Conor A. Nixon, NASA Goddard Space Flight Center (GSFC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], Science Systems and Applications, Inc. [Lanham] (SSAI), SRON Netherlands Institute for Space Research (SRON), Clarendon Laboratory [Oxford], University of Oxford [Oxford], and University of Oxford

Subjects
Atmospheres, 010504 meteorology & atmospheric sciences, Satellites, Atmospheric sciences, 01 natural sciences, symbols.namesake, Far infrared, 0103 physical sciences, Mixing ratio, Radiative transfer, Atmosphere of Titan, 010303 astronomy & astrophysics, Stratosphere, Spectroscopy, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [PHYS]Physics [physics], Satellites, Atmospheres, Astronomy and Astrophysics, Spectral bands, 13. Climate action, Space and Planetary Science, symbols, Atmospheres, Composition, Environmental science, Titan (rocket family), Titan, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Water vapor, Composition
Abstract

Here we report the measurement of water vapor in Titan's stratosphere using the Cassini Composite Infrared Spectrometer (CIRS, Flasar, F.M. et al. [2004]. Space Sci. Rev. 115, 169-297). CIRS senses water emissions in the far infrared spectral region near 50μm, which we have modeled using two independent radiative transfer codes (NEMESIS (Irwin, P.G.J. et al. [2008]. J. Quant. Spectrosc. Radiat. Trans. 109, 1136-1150) and ART (Coustenis, A. et al. [2007]. Icarus 189, 35-62; Coustenis, A. et al. [2010]. Icarus 207, 461-476). From the analysis of nadir spectra we have derived a mixing ratio of 0.14±0.05ppb at an altitude of 97km, which corresponds to an integrated (from 0 to 600km) surface normalized column abundance of 3.7±1.3×10 14molecules/cm 2. In the latitude range 80°S to 30°N we see no evidence for latitudinal variations in these abundances within the error bars. Using limb observations, we obtained mixing ratios of 0.13±0.04ppb at an altitude of 115km and 0.45±0.15ppb at an altitude of 230km, confirming that the water abundance has a positive vertical gradient as predicted by photochemical models (e.g. Lara, L.M., Lellouch, F., Lopez-Moreno, J.J., Rodrigo, R. [1996]. J. Geophys. Res. 101(23), 261; Wilson, E.H., Atreya, S.K. [2004]. J. Geophys. Res. 109, E6; Hörst, S.M., Vuitton, V., Yelle, R.V. [2008]. J. Geophys. Res., 113, E10). We have also fitted our data using scaling factors of ~0.1-0.6 to these photochemical model profiles, indicating that the models over-predict the water abundance in Titan's lower stratosphere. © 2012 Elsevier Inc..

Published
2012

154. GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration

Author

Boyle, E.A., John, S., Abouchami, W., Adkins, J.F., Echegoyen-Sanz, Y., Ellwood, M., Flegal, R., Fornace, K., Gallon, C., Galer, S., Gault-Ringold, M., Lacan, F., Radic, A., Rehkamper, M., Rouxel, Olivier, Sohrin, Y., Stirling, C., Thompson, C., Vance, D., Xue, Z., Zhao, Y., Massachusetts Institute of Technology (MIT), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Austalian National University, Australian National University (ANU), University of California [Santa Cruz] (UCSC), University of California, Department of Chemistry [Dunedin], University of Otago [Dunedin, Nouvelle-Zélande], Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), 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), Imperial College London, Woods Hole Oceanographic Institution (WHOI), Kyoto University [Kyoto], School of Earth Sciences [Bristol], University of Bristol [Bristol], University of California [Santa Cruz] (UC Santa Cruz), University of California (UC), 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), and Kyoto University

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract

International audience; We report data on the isotopic composition of cadmium, copper, iron, lead, zinc, and molybdenum at the GEOTRACES IC1 BATS Atlantic intercalibration station. In general, the between lab and within-lab precisions are adequate to resolve global gradients and vertical gradients at this station for Cd, Fe, Pb, and Zn. Cd and Zn isotopes show clear variations in the upper water column and more subtle variations in the deep water; these variations are attributable, in part, to progressive mass fractionation of isotopes by Rayleigh distillation from biogenic uptake and/or adsorption. Fe isotope variability is attributed to heavier crustal dust and hydrothermal sources and light Fe from reducing sediments. Pb isotope variability results from temporal changes in anthropogenic source isotopic compositions and the relative contributions of U.S. and European Pb sources. Cu and Mo isotope variability is more subtle and close to analytical precision. Although the present situation is adequate for proceeding with GEOTRACES, it should be possible to improve the within-lab and between-lab precisions for some of these properties.

Published
2012

155. Where might we find evidence of a Last Interglacial West Antarctic Ice Sheet collapse in Antarctic ice core records?

Author

Glenn A. Milne, Sarah L. Bradley, Valérie Masson-Delmotte, Eric W. Wolff, Mark Siddall, School of Earth Sciences [Bristol], University of Bristol [Bristol], Department of Earth Sciences [Ottawa], Carleton University, 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), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), 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), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), 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
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ice stream, Antarctic ice sheet, Antarctic sea ice, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Ice shelf, Ice-sheet model, Ice core, 13. Climate action, Climatology, Sea ice, Physical geography, Ice sheet, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Abundant indirect evidence suggests that the West Antarctic Ice Sheet (WAIS) reduced in size during the Last Interglacial (LIG) compared to the Holocene. This study explores this possibility by comparing, for the first time, ice core stable isotope records for the LIG with output from a glacio-isostatic adjustment (GIA) model. The results show that ice core records from East Antarctica are remarkably insensitive to vertical movement of the solid land motion driven by a simulated hypothetical collapse of the WAIS. However, new and so far unexplored sites are identified which are sensitive to the isostatic signal associated with WAIS collapse and so ice core proxy data from these sites would be effective in testing this hypothesis further.

Published
2012

156. ISOTOPIC RATIOS IN TITAN's METHANE: MEASUREMENTS AND MODELING

Author

C. D. Sherrill, Nicholas A Teanby, Richard K. Achterberg, Pgj Irwin, F. M. Flasar, Bruno Bézard, A. Coustenis, Berhane Temelso, Sandrine Vinatier, Conor A. Nixon, Kathleen Mandt, D. E. Jennings, Paul N. Romani, NASA Goddard Space Flight Center (GSFC), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], Science Systems and Applications, Inc. [Lanham] (SSAI), Southwest Research Institute [San Antonio] (SwRI), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford, and University of Oxford [Oxford]

Subjects
Physics, [PHYS]Physics [physics], 010304 chemical physics, Atmospheric methane, Astronomy and Astrophysics, Atmospheric sciences, 01 natural sciences, Methane, Astrobiology, Atmosphere, symbols.namesake, chemistry.chemical_compound, chemistry, 13. Climate action, Space and Planetary Science, Isotopes of carbon, 0103 physical sciences, symbols, Isotopologue, Atmosphere of Titan, Titan (rocket family), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Hydrodynamic escape
Abstract

The existence of methane in Titan's atmosphere (∼6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of ∼20Myr. In this paper, we examine the clues available from isotopic ratios (12C/13C and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH4 collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: 13CH4, 12CH3D, and 13CH3D. From these we compute estimates of 12C/13C= 86.5 ± 8.2 and D/H= (1.59 ± 0.33) × 10-4, in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH4+ C2H→ CH3+ C2H2. Using these new measurements and predictions we proceed to model the time evolution of 12C/13C and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model1 (no resupply of CH4), we find that the present-day 12C/13C implies that the CH4 entered the atmosphere 60-1600Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently - most likely less than 10Myr ago - if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing. We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric methane. © 2012 The American Astronomical Society. All rights reserved.

Published
2012

157. Lunar Net—a proposal in response to an ESA M3 call in 2010 for a medium sized mission

Author

Axel Hagermann, Lon L. Hood, Ian A. Crawford, Richard M. Ambrosi, Andrew David Griffiths, David J. Lawrence, C. Braithwaite, E. K. Gibson, Wojciech Marczewski, Patrick Brown, Martin Knapmeyer, V. Tong, Katarina Miljković, Glyn Collinson, Julian Chela-Flores, Nicholas A Teanby, Manuel Grande, J. Grygorczuk, Yang Gao, Philip Church, S. Ulamec, Ernesto Palomba, Andrew J. Coates, J. Heldmann, S. M. P. McKenna-Lawlor, Martin Sweeting, Neil Bowles, D. L. Talboys, G.W. Fraser, T. Cook, D. Pullan, Roman Wawrzaszek, O. B. Khavroshkin, Alan Smith, T. Cholinser, Richard C. Elphic, T. Colaprete, Timothy D. Glotch, Karol Seweryn, Ian Wright, Katherine H. Joy, Georgiana Y. Kramer, J. Rask, Lawrence A. Taylor, Nigel Bannister, Mark A. Wieczorek, Bruce Banerdt, G. Klingelhoefer, Mahesh Anand, R. A. Gowen, Adrian P. Jones, Murthy S. Gudipati, Andy Phipps, Timothy D. Swindle, Mark R. Sims, D. T. Richard, William T. Pike, Simon Sheridan, Lionel Wilson, Shyama Narendranath, Gareth S. Collins, Planetary and Space Sciences [Milton Keynes] (PSS), School of Physical Sciences [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), NASA, Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford [Oxford], Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), NASA Goddard Space Flight Center (GSFC), Sichuan University, Space Science Department, ASTRONIKA Sp. Zo.o., Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), The Open University [Milton Keynes] (OU), Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Space Technology Ireland Limited, Department of Mechanical Engineering [Imperial College London], Imperial College London, Space Research Centre [Leicester], University of Leicester, Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Beaumont Hospital, University of Cambridge [UK] (CAM), School of Earth Sciences [Bristol], University of Bristol [Bristol], German Aerospace Center (DLR), Institut de Physique du Globe de Paris (IPGP), 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)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU)-Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], and Sichuan University [Chengdu] (SCU)

Subjects
Physics, Solar System, 010504 meteorology & atmospheric sciences, Survivability, Astronomy and Astrophysics, Mars Exploration Program, 01 natural sciences, 7. Clean energy, Regolith, Identification (information), Resource (project management), [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Impact crater, 13. Climate action, Space and Planetary Science, Range (aeronautics), 0103 physical sciences, Systems engineering, Lunar Net, 010303 astronomy & astrophysics, Lunar, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Remote sensing
Abstract

Emplacement of four or more kinetic penetrators geographically distributed over the lunar surface can enable a broad range of scientific exploration objectives of high priority and provide significant synergy with planned orbital missions. Whilst past landed missions achieved a great deal, they have not included a far-side lander, or investigation of the lunar interior apart from a very small area on the near side. Though the LCROSS mission detected water from a permanently shadowed polar crater, there remains in-situ confirmation, knowledge of concentration levels, and detailed identification of potential organic chemistry of astrobiology interest. The planned investigations will also address issues relating to the origin and evolution of the Earth–Moon system and other Solar System planetary bodies. Manned missions would be enhanced with use of water as a potential in-situ resource; knowledge of potential risks from damaging surface Moonquakes, and exploitation of lunar regolith for radiation shielding. LunarNet is an evolution of the 2007 LunarEX proposal to ESA (European Space Agency) which draws on recent significant advances in mission definition and feasibility. In particular, the successful Pendine full-scale impact trials have proved impact survivability for many of the key technology items, and a penetrator system study has greatly improved the definition of descent systems, detailed penetrator designs, and required resources. LunarNet is hereby proposed as an exciting stand-alone mission, though is also well suited in whole or in-part to contribute to the jigsaw of upcoming lunar missions, including that of a significant element to the ILN (International Lunar Network).

Published
2012

158. Active upper-atmosphere chemistry and dynamics from polar circulation reversal on Titan

Author

F. Michael Flasar, S. B. Calcutt, Conor A. Nixon, Sandrine Vinatier, Athena Coustenis, Patrick G. J. Irwin, Nicholas A Teanby, Remco de Kok, Elliot Sefton-Nash, School of Earth Sciences [Bristol], University of Bristol [Bristol], SRON Netherlands Institute for Space Research (SRON), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), University of Oxford [Oxford], NASA Goddard Space Flight Center (GSFC), Agence Spatiale Européenne = European Space Agency (ESA), and University of Oxford

Subjects
[PHYS]Physics [physics], Multidisciplinary, Haze, 010504 meteorology & atmospheric sciences, Surface pressure, Atmospheric sciences, 01 natural sciences, Trace gas, Astrobiology, Troposphere, symbols.namesake, Planetary science, 13. Climate action, 0103 physical sciences, symbols, Life Science, Atmosphere of Titan, Thermosphere, Titan (rocket family), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Saturn's moon Titan has a nitrogen atmosphere comparable to Earth's, with a surface pressure of 1.4 bar. Numerical models reproduce the tropospheric conditions very well but have trouble explaining the observed middle-atmosphere temperatures, composition and winds. The top of the middle-atmosphere circulation has been thought to lie at an altitude of 450 to 500 kilometres, where there is a layer of haze that appears to be separated from the main haze deck. This 'detached' haze was previously explained as being due to the co-location of peak haze production and the limit of dynamical transport by the circulation's upper branch. Here we report a build-up of trace gases over the south pole approximately two years after observing the 2009 post-equinox circulation reversal, from which we conclude that middle-atmosphere circulation must extend to an altitude of at least 600 kilometres. The primary drivers of this circulation are summer-hemisphere heating of haze by absorption of solar radiation and winter-hemisphere cooling due to infrared emission by haze and trace gases; our results therefore imply that these effects are important well into the thermosphere (altitudes higher than 500 kilometres). This requires both active upper-atmosphere chemistry, consistent with the detection of high-complexity molecules and ions at altitudes greater than 950 kilometres, and an alternative explanation for the detached haze, such as a transition in haze particle growth from monomers to fractal structures.

Published
2012

159. The structure of liquid calcium aluminates as investigated by neutron and high-energy x-ray diffraction in combination with molecular dynamics simulation methods

Author

James W E Drewitt, Sandro Jahn, Viviana Cristiglio, Aleksei Bytchkov, Marlène Leydier, Séverine Brassamin, Henry E Fischer, Louis Hennet, School of Earth Sciences [Bristol], University of Bristol [Bristol], German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), European Synchrotron Radiation Facility (ESRF), Institut Laue-Langevin (ILL), ILL, Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), and Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, 550 - Earth sciences, 010306 general physics, Condensed Matter Physics, 01 natural sciences, ComputingMilieux_MISCELLANEOUS, 010305 fluids & plasmas
Abstract

International audience

Published
2012

160. First observation in the south of titan's far-infrared 220 cm-1 cloud

Author

Valeria Cottini, Athena Coustenis, Nicholas A Teanby, Richard K. Achterberg, Ronald Carlson, Robert E. Samuelson, Gordon L. Bjoraker, R. de Kok, V. G. Kunde, Georgios Bampasidis, Conor A. Nixon, C. M. Anderson, Paul N. Romani, Donald E. Jennings, Brigette E. Hesman, S. Vinatier, S. B. Calcutt, F. M. Flasar, NASA Goddard Space Flight Center (GSFC), Uni Research Climate, Uni Research Ltd, University of Florida [Gainesville] (UF), GSFC Laboratory for Extraterrestrial Physics, Science Systems and Applications, Inc. [Lanham] (SSAI), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, SRON Netherlands Institute for Space Research (SRON), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], University of Oxford [Oxford], and University of Oxford

Subjects
Sunlight, Physics, [PHYS]Physics [physics], 010504 meteorology & atmospheric sciences, Infrared, Astronomy, Astronomy and Astrophysics, 01 natural sciences, Latitude, Atmosphere, symbols.namesake, Atmosphere of Earth, Far infrared, 13. Climate action, Space and Planetary Science, atmospheres - planets and satellites: composition -planets and satellites: individual (Titan) - radiation mechanisms: thermal [processes - planets and satellites], 0103 physical sciences, processes - planets and satellites: atmospheres - planets and satellites: composition -planets and satellites: individual (Titan) - radiation mechanisms: thermal, symbols, Titan (rocket family), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Stratosphere, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

An emission feature at 220 cm-1 which has been attributed to a cloud of condensed material in Titan's winter stratosphere has been seen for the first time in the south. This feature had previously been found only at high northern latitudes during northern winter and spring. The material emitting at 220 cm-1, as yet unidentified, may be volatiles associated with nitrile gases that accumulate in the absence of ultraviolet sunlight. Not detected as recently as 2012 February, the 220 cm-1 feature clearly appeared at the south pole in Cassini spectra recorded on 2012 July 24, indicating a rapid onset of the emission. This is the first indication of the winter buildup of condensation in the southern stratosphere that has been expected as the south pole moves deeper into shadow. In the north the 220 cm-1 feature continued to decrease in intensity with a half-life of 3 years. © 2012. The American Astronomical Society. All rights reserved.

Published
2012

161. Sources and input mechanisms of hafnium and neodymium in surface waters of the Atlantic sector of the Southern Ocean

Author

Martin Frank, Joerg Rickli, Catherine Pradoux, Brian A. Haley, Catherine Jeandel, Ed C Hathorne, Torben Stichel, FM-GEOMAR, Leibniz Institute of Marine Sciences at the University of Kiel, SOEST, University of Hawai‘i [Mānoa] (UHM), School of Earth Sciences [Bristol], University of Bristol [Bristol], COAS, Oregon State University (OSU), GEOMAR LEGOS, 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 Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), 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), 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)-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
RARE-EARTH-ELEMENTS, Provenance, Water mass, 010504 meteorology & atmospheric sciences, MARINE-SEDIMENTS, DRAKE PASSAGE, Geotraces, 010502 geochemistry & geophysics, 01 natural sciences, WEDDELL GYRE, Geochemistry and Petrology, Ocean gyre, ISOTOPIC COMPOSITIONS, PACIFIC-OCEAN, 14. Life underwater, 0105 earth and related environmental sciences, Polar front, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, ANTARCTIC CIRCUMPOLAR CURRENT, Terrigenous sediment, 15. Life on land, NORTH-ATLANTIC, Oceanography, 13. Climate action, FERROMANGANESE CRUSTS, Seawater, CIRCULATION MODEL, Subtropical front, Geology
Abstract

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C., 2005, ENCY GEOLOGY, P132 STRAMMA L, 1990, J PHYS OCEANOGR, V20, P846, DOI 10.1175/1520-0485(1990)0202.0.CO;2 Tachikawa K, 1999, EARTH PLANET SC LETT, V170, P433, DOI 10.1016/S0012-821X(99)00127-2 Tanaka T, 2000, CHEM GEOL, V168, P279, DOI 10.1016/S0009-2541(00)00198-4 Taylor SR, 1985, CONTINENTAL CRUST IT THOMAS RJ, 1993, J AFR EARTH SCI, V16, P5, DOI 10.1016/0899-5362(93)90159-N van de Flierdt T, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2006GL026020 van de Flierdt T, 2002, EARTH PLANET SC LETT, V201, P639, DOI 10.1016/S0012-821X(02)00731-8 van de Flierdt T, 2012, LIMNOL OCEANOGR-METH, V10, P234, DOI 10.4319/lom.2012.10.234 van de Flierdt T, 2007, EARTH PLANET SC LETT, V259, P432, DOI 10.1016/j.epsl.2007.05.003 Vervoort JD, 1999, EARTH PLANET SC LETT, V168, P79, DOI 10.1016/S0012-821X(99)00047-3 WHITE WM, 1986, EARTH PLANET SC LETT, V79, P46, DOI 10.1016/0012-821X(86)90039-7 WHITWORTH T, 1980, DEEP-SEA RES, V27, P497, DOI 10.1016/0198-0149(80)90036-9 Zimmermann B, 2009, GEOCHIM COSMOCHIM AC, V73, P91, DOI 10.1016/j.gca.2008.09.033 Zimmermann B, 2009, GEOCHIM COSMOCHIM AC, V73, P3218, DOI 10.1016/j.gca.2009.02.028 Stichel, Torben Frank, Martin Rickli, Joerg Hathorne, Ed C. Haley, Brian A. Jeandel, Catherine Pradoux, Catherine Deutsche Forschungsgemeinschaft (DFG) [FR1198/2, SPP 1158] This study was funded by a Grant of the Deutsche Forschungsgemeinschaft (DFG) to M. F. (Project FR1198/2) within the priority program "Antarctic Research" (SPP 1158). We thank Jutta Heinze and Ana Kolevica for lab support and the chief scientists Eberhard Fahrbach and Hein de Baar, as well as Captain Stefan Schwarze and the crew of Polarstern for their contribution and bravery. Many thanks to Celia Venchiarutti for her help during sample collection and preparation. This manuscript was significantly improved by the comments and suggestions by editor Sidney Hemming and reviewers. 7 PERGAMON-ELSEVIER SCIENCE LTD OXFORD GEOCHIM COSMOCHIM AC; Radiogenic isotopes of hafnium (Hf) and neodymium (Nd) are powerful tracers for water mass transport and trace metal cycling in the present and past oceans. However, due to the scarcity of available data the processes governing their distribution are not well understood. Here we present the first combined dissolved Hf and Nd isotope and concentration data from surface waters of the Atlantic sector of the Southern Ocean. The samples were collected along the Zero Meridian, in the Weddell Sea and in the Drake Passage during RV Polarstern expeditions ANTXXIV/3 and ANTXXIII/3 in the frame of the International Polar Year (IPY) and the GEOTRACES program. The general distribution of Hf and Nd concentrations in the region is similar. However, at the northernmost station located 200 km southwest of Cape Town a pronounced increase of the Nd concentration is observed, whereas the Hf concentration is minimal, suggesting much less Hf than Nd is released by the weathering of the South African Archean cratonic rocks. From the southern part of the Subtropical Front (STF) to the Polar Front (PF) Hf and Nd show the lowest concentrations (

Published
2012

162. Uncertainties in elevation changes and their impact on Antarctic temperature records since the end of the last glacial period

Author

Valérie Masson-Delmotte, Glenn A. Milne, Mark Siddall, School of Earth Sciences [Bristol], University of Bristol [Bristol], Department of Earth Sciences [Ottawa], University of Ottawa [Ottawa], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), 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), 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), and 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)

Subjects
010504 meteorology & atmospheric sciences, Ice stream, Antarctic sea ice, 010502 geochemistry & geophysics, 01 natural sciences, Ice core, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Cryosphere, [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, Arctic ice pack, Ice-sheet model, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Sea ice thickness, sense organs, Physical geography, Ice sheet, Geology
Abstract

This study presents a sensitivity analysis considering the influence of elevation changes associated with both ice thickness and land height changes on water stable isotope temperature proxies from Antarctic ice cores. We compare results from three different ice sheet models and three different Earth viscosity models at a 10 ice core sites. As expected, the ice-thinning signal at West Antarctic sites is the largest contributor to elevation-induced temperature changes. The signal predicted by the ice models considered produced 100–200% of the total glacial to interglacial signal in δD, indicating that the deglacial ice thinning is overestimated by an amount approaching an order of magnitude at some locations. This indicates that the total volume loss in these models is considerably overestimated. Furthermore, the predicted rate of this change is not supported by the isotope data and so, again, most likely reflects inaccuracies in the adopted ice models. Estimates of contemporary ice mass changes inferred from satellite gravity data corrected using any of these models with therefore be biased as a result. The isostatic signal acts to reduce the total elevation change at most sites and has a relatively small magnitude (a few% to ~ 20% of that due to the ice thickness change) so is secondary at most sites and for most of the time. However, our results indicate that it could be the dominant control on elevation at some West Antarctic sites during the Holocene, resulting in a secular cooling signal of ~ 10–20‰ in δD. None of the models capture the Holocene isotopic depletion trend present at several sites in East Antarctica.

Published
2012

163. The Middle Devonian plant assemblage from Dechra Aït Abdallah (Morocco) revisited

Author

Martin Rücklin, Romain Blanchard, Brigitte Meyer-Berthaud, Cyrille Prestianni, Philippe Gerrienne, Gaël Clément, Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Paléobotanique, Paléopalynologie et Micropaléontologie, Université de Liège, School of Earth Sciences [Bristol], University of Bristol [Bristol], Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), ANR-06-BLAN-0347,ACCRO-Earth,Accidents in Climate Carbon cycle Regulation of the Earth(2006), Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD [France-Sud])

Subjects
0106 biological sciences, Flora, Taphonomy, 010502 geochemistry & geophysics, 010603 evolutionary biology, 01 natural sciences, Devonian, Paleontology, Abundance (ecology), Assemblage (archaeology), Fossil plants, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Gondwana, biology, Ecology, Middle Devonian, Leclercqia, 15. Life on land, biology.organism_classification, Morocco, Dechra Aït Abdallah, Eifelian, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology
Abstract

ACL-12-37; International audience; The composition of the allochthonous flora from Dechra Aït Abdallah (Central Morocco), initially described by Termier and Termier (1950), is reassessed from newly collected fossil material. Our work provides an updated taxonomic treatment of the plant remains. The flora comprises two lycophytes (including Leclercqia complexa), the probable iridopterid Anapaulia moodyi, and two aneurophytalean progymnosperms: Rellimia sp. and "Aneurophyton" maroccanum. Our revision confirms the Termiers' main conclusions that this Devonian flora is to date the most diverse and best known from Africa. Based on the complete paleontological evidence available from this locality, a Givetian age is as likely as an Eifelian age for the flora. The abundance of plant remains associated with the extreme scarcity of fertile organs may be accounted for by a taphonomic sorting, climatic conditions and/or specific ecological strategies. The flora of Dechra Aït Abdallah shows similarities with the Middle Devonian floras from the European part of Laurussia. This suggests that the paleogeographical position of Central Morocco permitted exchanges with Laurussia, and infers proximity of the latter with the north-western border of Gondwana during Middle Devonian times

Published
2012

164. Upper mantle anisotropy of southeast Arabia passive margin [Gulf of Aden northern conjugate margin], Oman

Author

Christel Tiberi, Michael Kendall, Cynthia Ebinger, George Helffrich, Ali Al-Lazki, Khalfan Al-Toobi, Graham Stuart, Sylvie Leroy, Department of Earth Sciences [Oman], Sultan Qaboos University (SQU), Department of Earth and Environmental Sciences [Rochester], University of Rochester [USA], School of Earth Sciences [Bristol], University of Bristol [Bristol], Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Manteau et Interfaces, Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), School of Earth and Environment [Leeds] (SEE), University of Leeds, and Earthquake Monitoring Center

Subjects
Seismic anisotropy, 010504 meteorology & atmospheric sciences, Proterozoic, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Crust, Shear wave splitting, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Passive margin, General Earth and Planetary Sciences, 14. Life underwater, Suture (geology), Anisotropy, Geology, 0105 earth and related environmental sciences, General Environmental Science, Terrane
Abstract

International audience; In this study, we used data recorded by two consecutive passive broadband deployments on the Gulf of Aden northern margin, Dhofar region, Sultanate of Oman. The objective of these deployments is to map the young eastern Gulf of Aden passive continental margin crust and upper mantle structure and rheology. In this study, we use shear-wave splitting analysis to map lateral variations of upper mantle anisotropy beneath the study area. In this study, we found splitting magnitudes to vary between 0.33 and 1.0 s delay times, averaging about 0.6 s for a total of 17 stations from both deployment periods. Results show distinct abrupt lateral anisotropy variation along the study area. Three anisotropy zones are identified: a western zone dominated by NW-SE anisotropy orientations, an eastern zone dominat- ed with NE-SW anisotropy orientations, and central zone with mixed anisotropy orientations similar to the east and west zones. We interpret these shorter wavelength anisotropy zones to possibly represent fossil lithospheric mantle anisotropy. We postulate that the central anisotropy zone may be representing a Proterozoic suture zone that separates two terranes to the east and west of it. The anisotropy zones west and east were being used indicative of different terranes with different upper mantle anisotropy signatures.

Published
2012

165. Deformation experiments of bubble and crystal bearing magmas : rheological and microstructural analysis

Author

Pistone, M., Caricchi, Luca, Ulmer, Pete, Burlini, L., Ardia, Paola, Reusser, Éric, Marone, Federica, Arbaret, Laurent, Institute for Geochemistry and Petrology, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), School of Earth Sciences [Bristol], University of Bristol [Bristol], 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), Department of Geology and Geophysics [Minneapolis], University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, The Swiss Light Source (SLS) (SLS-PSI), Paul Scherrer Institute (PSI), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), and Swiss National Foundation (grant 200020-120221)

Subjects
Condensed Matter::Soft Condensed Matter, Physics::Fluid Dynamics, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract

International audience; Simple shear deformation experiments on three-phase, hydrous, haplogranitic magmas, composed of quartz crystals (24-65 vol%), CO2-rich gas bubbles (9-12 vol%) and melt in different proportions, were performed with a Paterson-type rock deformation apparatus. Strain rates from 5*10-6 s-1 to 4*10-3 s-1 were applied at temperatures between 723 and 1023 K and at pressure of 200 MPa. The results show that the three-phase suspension rheology is strongly strain-rate dependent (non-Newtonian behavior). Two non-Newtonian regimes were observed: shear thinning (viscosity decreases with increasing strain rate) and shear thickening (viscosity increases with increasing strain rate). Shear thinning occurs in crystal-rich magmas (55-65 vol% crystals; 9-10 vol% bubbles) as a result of crystal size reduction and shear zoning. Shear thickening prevails in dilute suspensions (24 vol% crystals; 12 vol% bubbles), where bubble coalescence and outgassing dominate. At intermediate crystallinity (44 vol% crystals; 12 vol% bubbles) both shear thickening and thinning occur. Based on the microstructural observations using synchrotron radiation X-ray tomographic microscopy, bubbles can develop two different shapes: oblate at low temperature (< 873 K) and prolate at high temperature (> 873 K). These differences in shape are caused by different conditions of flow: unsteady flow, where the relaxation time of the bubbles is much longer than the timescale of deformation (oblate shapes); steady flow, where bubbles are in their equilibrium deformation state (prolate shapes). Three-phase magmas are characterized by a rheological behavior that is substantially different with respect to suspensions containing only crystals or only gas bubbles.

Published
2012

166. Uranus Pathfinder: exploring the origins and evolution of Ice Giant planets

Author

Abigail Rymer, S. Kemble, Elias Roussos, Sebastien Hess, Benoît Noyelles, Imke de Pater, Nick Sergis, Glyn Collinson, Stas Barabash, Ravit Helled, Jared Leisner, Chris S. Arridge, Nicholas A Teanby, Baptiste Cecconi, Andy F. Cheng, Norbert Krupp, Andrew Bacon, Joachim Saur, Yves Langevin, Andrew Fazakerley, Steve Miller, Jaques Gustin, Matthew S. Tiscareno, Christopher T. Russell, Mathieu Barthelemy, Nadine Nettelmann, Richard Holme, Philippe Zarka, Ingo Müller-Wodarg, Apostolos A. Christou, Andrew J. Coates, Robert Ebert, Thomas P. Andert, Olivier Mousis, Sandrine Vinatier, Paul M. Schenk, Gerald Schubert, Laurent Lamy, Michael Guest, Craig B. Agnor, Régis Courtin, Daniel Gautier, Jan-Erik Wahlund, Cesar Bertucci, Ulrich R. Christensen, Pontus Brandt, Javier Martin-Torres, Adam Masters, Don Banfield, Silvia Tellmann, Elizabeth P. Turtle, Matthew M. Hedman, Frank Sohl, Mark Hofstadter, Leigh N. Fletcher, Özgür Karatekin, Chris Paranicas, Kunio M. Sayanagi, Nicolas André, Agustín Sánchez-Lavega, Tom Stallard, Kevin H. Baines, Eric Quémerais, Martin Pätzold, Supriya Chakrabarti, Marina Galand, L. Peacocke, Pierre Henri, John F. Cooper, Gabriel Tobie, Marta Entradas, Nicholas Achilleos, Michele K. Dougherty, Renée Prangé, C. P. Chaloner, Henrik Melin, Geraint H. Jones, Jonathan J. Fortney, Edward C. Sittler, Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), School of Physics and Astronomy [London], Queen Mary University of London (QMUL), Centre d'étude spatiale des rayonnements (CESR), 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), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford [Oxford], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), University of Rostock [Germany], Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), University of California-University of California, Department of Physics and Astronomy [Leicester], University of Leicester, Cornell University, Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Astrium [Stevenage], EADS - European Aeronautic Defense and Space, Department of Physics and Astronomy [UCL London], Universität der Bundeswehr München [Neubiberg], Swedish Institute of Space Physics [Uppsala] (IRF), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-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)-Centre National de la Recherche Scientifique (CNRS), Instituto de Astronomía y Física del Espacio [Buenos Aires] (IAFE), Universidad de Buenos Aires [Buenos Aires] (UBA)-Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Center for Space Physics [Boston] (CSP), Boston University [Boston] (BU), Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Armagh Observatory [Armagh], NASA Goddard Space Flight Center (GSFC), Blackett Laboratory, Imperial College London, Southwest Research Institute [San Antonio] (SwRI), Department of Science and Technology Studies [London] (STS), University of California [Santa Cruz] (UCSC), University of California, Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, Department of Earth and Space Sciences [Los Angeles], University of Colorado [Boulder], School of Environmental Sciences [Liverpool], University of Liverpool, Royal Observatory of Belgium [Brussels], University of Iowa [Iowa City], Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Space Research Centre [Leicester], Fondation Universitaire Notre Dame de la Paix (FUNDP), Facultés Universitaires Notre-Dame de la Paix, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Astronomy [Berkeley], University of California [Berkeley], Rhenish Institute for Environmental Research (RIU), University of Cologne, HEPPI - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of the Basque Country/Euskal Herriko Unibertsitatea (UPV/EHU), Institute for Geophysics and Meteorology [Köln] (IGM), Lunar and Planetary Institute [Houston] (LPI), Office for Space Research and Applications [Athens], Academy of Athens, DLR Institute of Planetary Research, German Aerospace Center (DLR), School of Earth Sciences [Bristol], University of Bristol [Bristol], 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), University of Oxford, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), University of Rostock, University of California (UC)-University of California (UC), Cornell University [New York], Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), 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 d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Universidad de Buenos Aires [Buenos Aires] (UBA), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), University of California [Santa Cruz] (UC Santa Cruz), University of California (UC), Royal Observatory of Belgium [Brussels] (ROB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Facultés Universitaires Notre Dame de la Paix (FUNDP), University of California [Berkeley] (UC Berkeley), HELIOS - LATMOS, 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)-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, California Institute of Technology (CALTECH)-NASA, Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), 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), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Universität der Bundeswehr München [Neubiberg] = Bundeswehr University, 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)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Mullard Space Science Laboratory ( MSSL ), University College of London [London] ( UCL ), Queen Mary University of London ( QMUL ), Centre d'étude spatiale des rayonnements ( CESR ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] ( AOPP ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Institut d'astrophysique spatiale ( IAS ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules ( UTINAM ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Institute of Geophysics and Planetary Physics [Los Angeles] ( IGPP ), University of California at Los Angeles [Los Angeles] ( UCLA ), Laboratoire de Planétologie et Géodynamique de Nantes ( LPGN ), Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Swedish Institute of Space Physics [Uppsala] ( IRF ), Institut de Planétologie et d'Astrophysique de Grenoble ( IPAG ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), 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 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 ) -Centre National de la Recherche Scientifique ( CNRS ), Instituto de Astronomia y Fisica del Espacio ( IAFE ), Consejo Nacional de Investigaciones Científicas y Técnicas ( CONICET ) -Universidad de Buenos Aires [Buenos Aires], Johns Hopkins University Applied Physics Laboratory [Laurel, MD] ( APL ), Center for Space Physics [Boston] ( CSP ), Boston University [Boston] ( BU ), Max Planck Institute for Solar System Research ( MPS ), NASA Goddard Space Flight Center ( GSFC ), Southwest Research Institute [San Antonio] ( SwRI ), Department of Science and Technology Studies [London] ( STS ), University of California [Santa Cruz] ( UCSC ), Laboratoire de Physique Atmosphérique et Planétaire ( LPAP ), University of Colorado Boulder [Boulder], University of Iowa [Iowa], Centro de Astrobiologia [Madrid] ( CAB ), Instituto Nacional de Técnica Aeroespacial ( INTA ) -Consejo Superior de Investigaciones Científicas [Spain] ( CSIC ), Fondation Universitaire Notre Dame de la Paix ( FUNDP ), Institut de Mécanique Céleste et de Calcul des Ephémérides ( IMCCE ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), Astronomy Department [Berkeley], Rhenish Institute for Environmental Research ( RIU ), Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), University of the Basque Country/Euskal Herriko Unibertsitatea ( UPV/EHU ), Institute for Geophysics and Meteorology [Köln] ( IGM ), Lunar and Planetary Institute [Houston] ( LPI ), and German Aerospace Center ( DLR )

Subjects
Solar System, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Ciencias Físicas, Uranus, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], interior, Natural satellite, 7. Clean energy, 01 natural sciences, Astrobiology, Ice Giant, Orbiter, Neptune, Planet, 0103 physical sciences, 010303 astronomy & astrophysics, ICE GIANT, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], natural satellite, ice giants, Nice model, Giant planet atmosphere, Astronomy, Astronomy and Astrophysics, Planetary system, [ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Ring system, Dynamo, Astronomía, [ PHYS.ASTR.EP ] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], URANUS, 13. Climate action, Space and Planetary Science, Exploration of Uranus, Magnetosphere, GIANT PLANET ATMOSPHERE, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ORBITER, CIENCIAS NATURALES Y EXACTAS, Ice giant
Abstract

The “Ice Giants” Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA’s Cosmic Vision 2015–2025. UP was proposed to the European Space Agency’s M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines the need to develop power sources suitable for the outer Solar System. The UP science case is based around exploring the origins, evolution, and processes at work in Ice Giant planetary systems. Three broad themes were identified: (1) Uranus as an Ice Giant, (2) An Ice Giant planetary system, and (3) An asymmetric magnetosphere. Due to the long interplanetary transfer from Earth to Uranus a significant cruise-phase science theme was also developed. The UP mission concept calls for the use of a Mars Express/Rosetta-type platform to launch on a Soyuz–Fregat in 2021 and entering into an eccentric polar orbit around Uranus in the 2036–2037 timeframe. The science payload has a strong heritage in Europe and beyond and requires no significant technology developments. Fil: Arridge, Christopher S.. University College London; Estados Unidos Fil: Agnor, Craig B.. Queen Mary University of London; Reino Unido Fil: Andre, Nicolas. Centre National de la Recherche Scientifique; Francia Fil: Baines, Kevin H.. National Aeronautics And Space Administration; Estados Unidos Fil: Fletcher, Leigh N.. University of Oxford; Reino Unido Fil: Gautier, Daniel. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Hofstadter, Mark D.. National Aeronautics And Space Administration; Estados Unidos Fil: Jones, Geraint H.. University College London; Estados Unidos Fil: Lamy, Laurent. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Langevin, Yves. Centre National de la Recherche Scientifique; Francia Fil: Mousis, Olivier. Centre National de la Recherche Scientifique; Francia Fil: Nettelmann, Nadine. Universitat Rostock; Alemania Fil: Russell, Christopher T.. University of California at Los Angeles; Estados Unidos Fil: Stallard, Tom. University of Leicester; Reino Unido Fil: Tiscareno, Matthew S.. Cornell University; Estados Unidos Fil: Tobie, Gabriel. Centre de Recherche de Nantes; Francia Fil: Bacon, Andrew. Systems Engineering and Asssessment Ltd; Reino Unido Fil: Chaloner, Chris. Systems Engineering and Asssessment Ltd; Reino Unido Fil: Guest, Michael. Systems Engineering and Asssessment Ltd; Reino Unido Fil: Kemble, Steve. Astrium; Reino Unido Fil: Peacocke, Lisa. Astrium; Reino Unido Fil: Achilleos, Nicholas. University College London; Estados Unidos Fil: Andert, Thomas P.. Universität der Bundeswehr; Alemania Fil: Banfield, Don. Cornell University; Estados Unidos Fil: Barabash, Stas. Sweden Institute of Space Physics; Suecia Fil: Barthelemy, Matthieu. Universite Joseph Fourier; Francia Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Brandt, Pontus. University Johns Hopkins; Estados Unidos Fil: Cecconi, Baptiste. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia Fil: Chakrabarti, Supriya. Boston University; Estados Unidos

Published
2012

167. Changes in methanogenic substrate utilization and communities with depth in a salt-marsh, creek sediment in southern England

Author

John C. Fry, Ronald John Parkes, Erwan George Philippe Roussel, Edward R. C. Hornibrook, Andrew J. Weightman, Natasha Banning, Fiona Brock, School of Earth and Ocean Sciences [Cardiff], Cardiff University, Bristol Biogeochemistry Research Centre, School of Earth Sciences [Bristol], University of Bristol [Bristol]-University of Bristol [Bristol], and School of Biosciences [Cardiff]

Subjects
animal structures, Methanogenesis, [SDE.MCG]Environmental Sciences/Global Changes, Aquatic Science, Oceanography, Methanosaeta, Methane, 03 medical and health sciences, chemistry.chemical_compound, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, 0303 health sciences, biology, 030306 microbiology, Ecology, biology.organism_classification, Methanogen, Anoxic waters, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, chemistry, 13. Climate action, Environmental chemistry, Anaerobic oxidation of methane, Methanosarcinales, Methanomicrobiales, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, [SDV.EE.IEO]Life Sciences [q-bio]/Ecology, environment/Symbiosis
Abstract

A combined biogeochemical and molecular genetic study of creek sediments (down to 65 cm depth) from Arne Peninsula salt-marsh (Dorset, UK) determined the substrates used for methanogenesis and the distribution of the common methanogens, Methanosarcinales and Methanomicrobiales capable of metabolising these substrates. Methane concentrations increased by 11 cm, despite pore water sulphate not being removed until 45 cm. Neither upward methane diffusion or anaerobic oxidation of methane seemed to be important in this zone. In the near-surface sulphate-reduction zone (5–25 cm) turnover time to methane for the non-competitive methanogenic substrate trimethylamine was most rapid (80 days), and were much longer for acetate (7900 days), methanol (40,500 days) and bicarbonate (361,600 days). Methylamine-utilizing Methanosarcinales were the dominant (60–95%) methanogens in this zone. In deeper sediments rates of methanogenesis from competitive substrates increased substantially, with acetate methanogenic rates becoming ∼100 times greater than H2/CO2 methanogenesis below 50 cm. In addition, there was a dramatic change in methanogen diversity with obligate acetate-utilizing, Methanosaeta related sequences being dominant. At a similar depth methanol turnover to methane increased to its most rapid (1700 days). This activity pattern is consistent with deeper methanogen populations (55 cm) being dominated by acetate-utilizing Methanosaeta with H2/CO2 and alcohol-utilizing Methanomicrobiales also present. Hence, there is close relationship between the depth distribution of methanogenic substrate utilization and specific methanogens that can utilize these compounds. It is unusual for acetate to be the dominant methanogenic substrate in coastal sediments and δ13C-CH4 values (−74 to −71‰) were atypical for acetate methanogenesis, suggesting that common stable isotope proxy models may not apply well in this type of dynamic anoxic sediment, with multiple methanogenic substrates.

Published
2012

168. GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles. Part 1: reproducibility of results for the international intercomparison

Author

van de Flierdt, T., Pahnke, K., Amakawa, H., Andersson, P., Basak, C., Coles, B., Colin, C., Crocket, K., Frank, M., Frank, N., Goldstein, S. L., Goswami, V., Haley, B. A., Hathorne, E. C., Hemming, S. R., Henderson, G. M., Jeandel, C., Jones, K., Kreissig, K., Lacan, F., Lambelet, M., Martin, E. E., Newkirk, D. R., Obata, H., Pena, Luisa, Piotrowski, A. M., Pradoux, C., Scher, H. D., Schoberg, H., Singh, S. K., Stichel, T., Tazoe, H., Vance, D., Yang, J. J., Department of Earth Science and Technology [Imperial College London], Imperial College London, Department of Geology and Geophysics, University of Hawaii, Marine Isotope Geochemistry Group, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg-University of Oldenburg-Max Planck Institute for Marine Microbiology, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Atmosphere and Ocean Research Institute [Kashiwa-shi] (AORI), The University of Tokyo (UTokyo), Department of Geosciences, National Taiwan University [Taiwan] (NTU), Laboratory for Isotope Geology, Swedish Museum of Natural History (NRM), Department of Geological Sciences, University of Florida [Gainesville] (UF), Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Géochrononologie Traceurs Archéométrie (GEOTRAC), 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), Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Department of Earth and Environmental Sciences [New York], Geosciences Division [Ahmedabad], Physical Research Laboratory [Ahmedabad] (PRL), Indian Space Research Organisation (ISRO)-Indian Space Research Organisation (ISRO), FM-GEOMAR, Leibniz Institute of Marine Sciences at the University of Kiel, Department of Earth Sciences [Oxford], University of Oxford, GEOMAR LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), 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)-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)-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), Godwin Laboratory for Palaeoclimate Research, University of Cambridge [UK] (CAM), Department of Earth and Ocean Sciences [Columbia], University of South Carolina [Columbia], Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, School of Earth Sciences [Bristol], University of Bristol [Bristol], Laboratoire des Interactions et Dynamique des Environnements de Surface, CNRS-Université de Paris-Sud, 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)-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), University of Oxford [Oxford], 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 Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and 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)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, OCEAN, ROCKS, PARTICULATE MATTER, ISLAND ARCS, ISOTOPES, ND, EXCHANGE, MASS DISCRIMINATION, SR, NORTH PACIFIC, EVOLUTION, Panoply
Abstract

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Goswami, Vineet Haley, Brian A. Hathorne, Ed C. Hemming, Sidney R. Henderson, Gideon M. Jeandel, Catherine Jones, Kevin Kreissig, Katharina Lacan, Francois Lambelet, Myriam Martin, Ellen E. Newkirk, Derrick R. Obata, Haijme Pena, Leopoldo Piotrowski, Alexander M. Pradoux, Catherine Scher, Howie D. Schoberg, Hans Singh, Sunil Kumar Stichel, Torben Tazoe, Hirofumi Vance, Derek Yang, Jingjing Lacan, Francois/B-8032-2009; Scher, Howie/C-4927-2013; Pena, Leopoldo/B-8140-2013; Crocket, Kirsty/G-6327-2013 Crocket, Kirsty/0000-0003-2171-3010 NSF [OCE-07-52402]; Marie Curie International Reintegration [IRG 230828]; NERC [NE/F016751/1]; U.S. National Science Foundation [OCE-927285] We would like to extend a special word of thanks to Bob Anderson, Marty Fleisher, and Tim Kenna for being a great team to work with during this GEOTRACES intercalibration. Thanks also to crew and colleagues who sailed on the two intercalibration cruises on the R/V Knorr, and to Greg Cutter, Ken Bruland, and Rob Sherrell for leading the GEOTRACES intercalibration effort. Thermo Fisher Scientific and Gideon Henderson are thanked for providing the unknown Nd isotope and REE standards. Wafa Abouchami, associate editor Peter Croot, and two anonymous reviewers are thanked for providing constructive reviews. Funding was provided by NSF grant OCE-07-52402 to TvdF and KP, and by Marie Curie International Reintegration grant IRG 230828 and NERC grantNE/F016751/1 to TvdF. This paper is part of the Intercalibration in Chemical Oceanography special issue of L&O Methods that was supported by funding from the U.S. National Science Foundation, Chemical Oceanography Program (Grant OCE-927285 to G. Cutter). 14 AMER SOC LIMNOLOGY OCEANOGRAPHY WACO LIMNOL OCEANOGR-METH; One of the key activities during the initial phase of the international GEOTRACES program was an extensive international intercalibration effort, to ensure that results for a range of trace elements and isotopes (TEIs) from different cruises and from different laboratories can be compared in a meaningful way. Here we present the results from the intercalibration efforts on neodymium isotopes and rare earth elements in seawater and marine particles. Fifteen different laboratories reported results for dissolved Nd-143/Nd-144 ratios in seawater at three different locations (BATS 15 m, BATS 2000 m, SAFe 3000 m), with an overall agreement within 47 to 57 ppm (2 sigma standard deviation of the mean). A similar agreement was found for analyses of an unknown pure Nd standard solution carried out by 13 laboratories (56 ppm), indicating that mass spectrometry is the main variable in achieving accurate and precise Nd isotope ratios. Overall, this result is very satisfactory, as the achieved precision is a factor of 40 better than the range of Nd isotopic compositions observed in the global ocean. Intercalibration for dissolved rare earth element concentrations (REEs) by six laboratories for two water depths at BATS yielded a reproducibility of 15% or better for all REE except Ce, which seems to be the most blank-sensitive REE. Neodymium concentrations from 12 laboratories show an agreement within 9%, reflecting the best currently possible reproducibility. Results for Nd isotopic compositions and REE concentrations on marine particles are inconclusive, and should be revisited in the future.

Published
2012

169. The shapes of dikes: Evidence for the influence of cooling and inelastic deformation

Author

Katherine A. Daniels, J. Sparks R. Stephen, Thierry Menand, Janine Kavanagh, School of Earth Sciences [Bristol], University of Bristol [Bristol], School of Geosciences, Monash University [Clayton], Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Basalt, Dike, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Geology, Tapering, Crust, 010502 geochemistry & geophysics, 01 natural sciences, Overpressure, Stress (mechanics), Magma, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Geomorphology, Kimberlite, 0105 earth and related environmental sciences
Abstract

International audience; We document the shape of dikes from well exposed field locations in the Isle of Rum, Scotland,14 and Helam Mine, South Africa. The basaltic Rum dikes crop out on a smaller scale than the15 Helam kimberlite dikes and have a smaller length to thickness ratio (~100:1 Isle of Rum,16 ~1000:1 Helam Mine). We compare dike thickness field measurements with the geometry17 predicted by elastic theory, finding best-fit models to estimate magma overpressure and regional18 stress gradients at the time of dike emplacement. Most of the dike shapes fit poorly with elastic19 theory, being too thick at the dike ends and too narrow in the middle. Our calculated20 overpressures and stress gradients are much larger than independent estimates based on rock21 strength. Dike shape can be explained by a combination of host rock inelastic deformation and22 magma chilling at the dike’s tapering edges preventing its closure as magma pressure declines23 during emplacement. The permanent wedging of the dike edges due to chilling has implications24 for crustal magma transport and strain response in the crust due to dike emplacement

Published
2012

170. Variations of Li and Mg isotope ratios in bulk chondrites and mantle xenoliths

Author

Yi-Jen Lai, Horst R. Marschall, Dmitri A. Ionov, A. Jeffcoate, Tim Elliott, Philip A.E. Pogge von Strandmann, Christopher D. Coath, School of Earth Sciences [Bristol], University of Bristol [Bristol], Woods Hole Oceanographic Institution (WHOI), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Olivine, 010504 meteorology & atmospheric sciences, Mantle wedge, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Isotope fractionation, 13. Climate action, Geochemistry and Petrology, Chondrite, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, engineering, Enstatite, Xenolith, Primitive mantle, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

We present whole rock Li and Mg isotope analyses of 33 ultramafic xenoliths from the terrestrial mantle, which we compare with analyses of 30 (mostly chondritic) meteorites. The accuracy of our new Mg isotope ratio measurement protocol is substantiated by a combination of standard addition experiments, the absence of mass independent effects in terrestrial samples and our obtaining identical values for rock standards using two different separation chemistries and three different mass-spectrometric introduction systems. Carbonaceous, ordinary and enstatite chondrites have irresolvable mean stable Mg isotopic compositions (δ 25Mg=-0.14±0.06; δ 26Mg=-0.27±0.12‰, 2SD), but our enstatite chondrite samples have lighter δ 7Li (by up to ~3‰) than our mean carbonaceous and ordinary chondrites (3.0±1.5‰, 2SD), possibly as a result of spallation in the early solar system. Measurements of equilibrated, fertile peridotites give mean values of δ 7Li=3.5±0.5‰, δ 25Mg=-0.10±0.03‰ and δ 26Mg=-0.21±0.07‰. We believe these values provide a useful estimate of the primitive mantle and they are within error of our average of bulk carbonaceous and ordinary chondrites. A fuller range of fresh, terrestrial, ultramafic samples, covering a variety of geological histories, show a broad positive correlation between bulk δ 7Li and δ 26Mg, which vary from -3.7‰ to +14.5‰, and -0.36‰ to + 0.06‰, respectively. Values of δ 7Li and δ 26Mg lower than our estimate of primitive mantle are strongly linked to kinetic isotope fractionation, occurring during transport of the mantle xenoliths. We suggest Mg and Li diffusion into the xenoliths is coupled to H loss from nominally anhydrous minerals following degassing. Diffusion models suggest that the co-variation of Mg and Li isotopes requires comparable diffusivities of Li and Mg in olivine. The isotopically lightest samples require ~5-10years of diffusive ingress, which we interpret as a time since volatile loss in the host magma. Xenoliths erupted in pyroclastic flows appear to have retained their mantle isotope ratios, likely as a result of little prior degassing in these explosive events. High δ 7Li, coupled with high [Li], in rapidly cooled arc peridotites may indicate that these samples represent fragments of mantle wedge that has been metasomatised by heavy, slab-derived fluids. If such material is typically stirred back into the convecting mantle, it may account for the heavy δ 7Li seen in some oceanic basalts. © 2011 Elsevier Ltd.

Published
2011

171. Synthetic zircon doped with hafnium and rare earth elements: A reference material for in situ hafnium isotope analysis

Author

Janne Blichert-Toft, Scott D. Samson, John M. Hanchar, Rebecca Lam, Bruno Dhuime, Christopher M. Fisher, Jeffery D. Vervoort, Department of Earth Sciences [St. John's], Memorial University of Newfoundland [St. John's], Department of Earth Sciences [Syracuse], Syracuse University, Department of Earth Sciences [St Andrews], University of St Andrews [Scotland], School of Earth Sciences [Bristol], University of Bristol [Bristol], 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), School of Earth and Environmental Sciences, Washington State University (WSU), INCO Innovation Centre, Memorial Unversity of Newfoundland, Mineralogical Society of America, Canadian Natural Sciences and Research Council (NSERC), University of Newfoundland, INSU : Institut National des Sciences de l'Univers, NERC : NE/E005225/1Memorial, Department of Earth and Environmental Sciences, George Washington University, The George Washington University (GW), Laboratoire de Sciences de la Terre (LST), Memorial University of Newfoundland = Université Memorial de Terre-Neuve [St. John's, Canada] (MUN), 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), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ytterbium, In situ, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Analytical chemistry, chemistry.chemical_element, Mineralogy, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, Mass spectrometry, 01 natural sciences, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Isotope analysis, Laser ablation, Doping, Geology, Synthetic zircon, Hafnium isotopes, Hafnium, Isobaric interference, chemistry, Reference material, Zircon
Abstract

International audience; A series of flux-grown synthetic zircon crystals doped with Hf and selected rare earth elements (REE) were produced for use as a potential reference material for Lu-Hf isotopic analysis of zircon by in situ laser ablation multi-collector inductively-coupled plasma mass spectrometry (LA-MC-ICPMS). The synthetic zircon crystals were doped such as to produce a large range of REE/Hf, allowing for a robust means of monitoring and correcting the sometimes large (176)Yb and (176)Lu isobaric interferences on the low-abundance (176)Hf in natural zircon, as well as potential oxide interferences from Gd, Tb, and Dy. The synthetic zircon crystals have a homogeneous Hf isotopic composition, both within and between grains, as documented by solution MC-ICPMS analyses of Hf chemically separated from multiple fragments of zircon from three different syntheses, and 321 laser ablation MC-ICPMS analyses done in two different laboratories. An additional 110 in situ analyses of natural zircon crystals reveal identical behavior of natural and synthetic zircon during Hf isotope analysis by laser ablation. Hence, the synthetic zircon crystals provide a means of monitoring a wide range of Yb and Lu interferences (up to 50% of the total signal intensity at mass 176) during routine isotopic analysis for geological studies. They also may be helpful in developing improved laboratory protocols for accurate in situ Lu-Hf isotopic measurement of natural zircon. The present data illustrate the importance of the (176)Yb interference correction on (176)Hf, which can result in large biases if not properly applied to natural samples with their variable and often high (176)Yb/(177)Hf. This study definitively shows that use of high-REE/Hf synthetic zircon standards for calibrating the Yb mass bias correction is more accurate than use of Yb-doped natural Hf solutions. Finally, the results of the present work suggest that synthetic minerals may prove useful as both in situ method development tools and isotopic reference materials.

Published
2011

172. Emplacement of magma pulses and growth of magma bodies

Author

Michel de Saint-Blanquat, Thierry Menand, Catherine Annen, University of Bristol [Bristol], Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-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-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), School of Earth Sciences [Bristol], 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), 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)-Université Fédérale Toulouse Midi-Pyrénées-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), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), 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
Earth science, Pluton, Granite, Plutons, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Magma chamber, 010502 geochemistry & geophysics, 01 natural sciences, Sill, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 010503 geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, Incremental emplacement, geography.geographical_feature_category, Continental crust, Sills, Crust, Plutonism, Geophysics, 13. Climate action, Magmatism, Igneous differentiation, Geology
Abstract

International audience; Magmatism is responsible for the formation of continental and oceanic crusts. It is the main agent of mass and heat transfers from the mantle towards the crust, the hydrosphere (oceanic and continental hydrothermalism) and the atmosphere (emissions of volcanic gas and ashes). Its expressions are the crystallization of intrusive rocks and the eruption of volcanic products. However, with a ratio between the volumes of extrusive and intrusive magmatic rocks estimated to be of the order of 1:5 for most magmatic systems (White et al., 2006), one of the main characteristics of magmatism is that magmas rarely reach the Earth's surface. This suggests that the prevailing conditions in the crust are not favourable to the arrival of magma on the Earth's surface, but instead lean heavily towards the formation of intrusive bodies in the crust. These intrusive bodies, referred to here as plutons, constitute the elementary building brick of the continental crust. An increasing number of geophyscial and geochronological data as well as geological observations is currently modifying our understanding of pluton construction. When plutons were initially envisaged as quasi-spherical bodies growing slowly and essentially by an overall inflation, they are now recognized as growing incrementally by the accretion of successive and relatively small magma pulses, over variable periods of time, from hundred to millions of years, depending on geodynamic setting and source fertility. This brings new challenges and has far-reaching implications. According to this new model of plutonism, the evolution of magma bodies is related to the processes that control the timescale and the spatial distribution of the successive pulses. Depending on their emplacement rate and on their ability to amalgamate, repeated magma pulses can either rapidly solidify or ultimately build up an active magma chamber. Thus understanding how magma bodies grow has fundamental implications for the link between volcanism and plutonism as well as for magma differentiation and ultimately for our understanding of the growth and evolution of the Earth crusts. The concept of pluton incremental growth challenges our understanding as well as our field interpretations of the processes involved during pluton construction. Indeed, these processes and how they operate in governing the emplacement and growth of plutons, both in space and time, are still debated.A state-of-the-art session on these very issues was held at the 2008 General Assembly of the European Geosciences Union. As a follow-up of this session, this special volume Emplacement of magma pulses and growth of magma bodies brings together both theoretical models and field studies that cover most aspects of the emplacement and growth of plutons.

Published
2011
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173. Lithosphere-asthenosphere interaction beneath Ireland from joint inversion of teleseismic P-wave delay times and GRACE gravity

Author

O'Donnell, J. P., Daly, E., Tiberi, Christel, Bastow, I. D., O'Reilly, B. M., Readman, P. W., Hauser, F., Department of Earth and Ocean Sciences [Galway], National University of Ireland [Galway] (NUI Galway), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], Dublin Institute for Advanced Studies (DIAS), School of Geological Sciences [Dublin], University College Dublin [Dublin] (UCD), Manteau et Interfaces, and Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
british-isles, Seismic tomography, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, suture zone, proto-iceland plume, Gravity anomalies, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], dynamics of lithosphere and mantle, crustal structure, Body waves, continental lithosphere, arrival times, Dynamics of lithosphere, velocity structure, gravity anomalies and earth structure, north-atlantic, europe, upper-mantle, Earth structure
Abstract

International audience; The nature and extent of the regional lithosphere-asthenosphere interaction beneath Ireland and Britain remains unclear. Although it has been established that ancient Caledonian signatures pervade the lithosphere, tertiary structure related to the Iceland plume has been inferred to dominate the asthenosphere. To address this apparent contradiction in the literature, we image the 3-D lithospheric and deeper upper-mantle structure beneath Ireland via non-linear, iterative joint teleseismic-gravity inversion using data from the ISLE (Irish Seismic Lithospheric Experiment), ISUME (Irish Seismic Upper Mantle Experiment) and GRACE (Gravity Recovery and Climate Experiment) experiments. The inversion combines teleseismic relative arrival time residuals with the GRACE long wavelength satellite derived gravity anomaly by assuming a depth-dependent quasilinear velocity-density relationship. We argue that anomalies imaged at lithospheric depths probably reflect compositional contrasts, either due to terrane accretion associated with Iapetus Ocean closure, frozen decompressional melt that was generated by plate stretching during the opening of the north Atlantic Ocean, frozen Iceland plume related magmatic intrusions, or a combination thereof. The continuation of the anomalous structure across the lithosphere-asthenosphere boundary is interpreted as possibly reflecting sub-lithospheric small-scale convection initiated by the lithospheric compositional contrasts. Our hypothesis thus reconciles the disparity which exists between lithospheric and asthenospheric structure beneath this region of the north Atlantic rifted margin.

Published
2011

174. The structure of liquid calcium aluminates as investigated using neutron and high energy x-ray diffraction in combination with molecular dynamics simulation methods

Author

Sandro Jahn, James W E Drewitt, Henry E. Fischer, S. Brassamin, Viviana Cristiglio, Louis Hennet, A. Bytchkov, M. Leydier, School of Earth Sciences [Bristol], University of Bristol [Bristol], German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), European Synchrotron Radiation Facility (ESRF), Institut Laue-Langevin (ILL), ILL, Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), and Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
550 - Earth sciences, 02 engineering and technology, Crystal structure, 01 natural sciences, Molecular physics, symbols.namesake, chemistry.chemical_compound, Molecular dynamics, 0103 physical sciences, General Materials Science, Neutron, Calcium aluminates, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Chemistry, Pair distribution function, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 3. Good health, Crystallography, Chemical bond, X-ray crystallography, symbols, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, Raman spectroscopy
Abstract

The structure of laser heated aerodynamically levitated (CaO)(x)(Al₂O₃)(1-x) high temperature liquids, with x = 0.33, 0.5, 0.75, was measured by using neutron and high energy x-ray diffraction. The partial structure factors for the liquids at 2500 K were also determined using molecular dynamics computer simulations. The simulation results are in excellent agreement with the diffraction measurements. The results show a predominant tetrahedral Al coordination with approximately 20% of fivefold coordinated Al at x = 0.33 which reduces with increasing CaO concentration. The Ca atoms occupy a broad range of coordination environments but with a predominance of sixfold distorted octahedra. The simulations confirm the presence of 13, 7 and 0.6% OAl₃ triclusters connecting AlO₄ tetrahedra in the structure of CA2 (x = 0.33), CA (x = 0.5) and C3A (x = 0.75) liquids, respectively.

Published
2011

175. Strain-Induced Magma Degassing: Insights From Simple-Shear Experiments on Bubble Bearing Melts

Author

Mattia Pistone, Diego Perugini, Luca Caricchi, Jonathan M. Castro, Alain Burgisser, Anne Pommier, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), Institute for Geochemistry and Petrology, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), School of Geosciences, Monash University [Clayton], Department of Earth Sciences [Perugia], Università degli Studi di Perugia (UNIPG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Obsidian banding, 010504 meteorology & atmospheric sciences, Bubble, [SDE.MCG]Environmental Sciences/Global Changes, Mineralogy, 010502 geochemistry & geophysics, 01 natural sciences, law.invention, Optical microscope, Geochemistry and Petrology, law, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Magma deformation, Strain-induced degassing, Bubble deformation, Composite material, Fourier transform infrared spectroscopy, Water content, 0105 earth and related environmental sciences, Overburden pressure, Pressure vessel, Simple shear, Shear (geology), 13. Climate action, Geology
Abstract

International audience; Experiments have been performed to determine the effect of deformation on degassing of bubble-bearing melts. Cylindrical specimens of phonolitic composition, initial water content of 1.5 wt.% and 2 vol.% bubbles, have been deformed in simple-shear (torsional configuration) in an internally heated Paterson-type pressure vessel at temperatures of 798-848 K, 100-180 MPa confining pressure and different final strains. Micro-structural analyses of the samples before and after deformation have been performed in two and three dimensions using optical microscopy, a nanotomography machine and synchrotron tomography. The water content of the glasses before and after deformation has been measured using Fourier Transform Infrared Spectroscopy (FTIR). In samples strained up to a total of γ ∼ 2 the bubbles record accurately the total strain, whereas at higher strains (γ ∼ 10) the bubbles become very flattened and elongate in the direction of shear. The residual water content of the glasses remains constant up to a strain of γ ∼ 2 and then decreases to about 0.2 wt.% at γ ∼ 10. Results show that strain enhances bubble coalescence and degassing even at low bubble volume-fractions. Noticeably, deformation produced a strongly water under-saturated melt. This suggests that degassing may occur at great depths in the volcanic conduit and may force the magma to become super-cooled early during ascent to the Earth's surface potentially contributing to the genesis of obsidian.

Published
2011

176. The H2O solubility of alkali basaltic melts: an experimental study

Author

Michel Pichavant, Jean-Michel Bény, Bruno Scaillet, Priscille Lesne, Giada Iacono-Marziano, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], INGV funds and by the department of the Italian Civil Defence., and Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS)

Subjects
Basalt, Aqueous solution, Experimental petrology, 010504 meteorology & atmospheric sciences, Chemistry, Water solubility, [SDE.MCG]Environmental Sciences/Global Changes, Analytical chemistry, partial molar volume, Mineralogy, Partial molar property, Context (language use), Alkali basalts, 010502 geochemistry & geophysics, Alkali metal, 01 natural sciences, Water speciation, Geophysics, 13. Climate action, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Solubility, Glass transition, 0105 earth and related environmental sciences
Abstract

Experiments were conducted to determine the water solubility of alkali basalts from Etna, Stromboli and Vesuvius volcanoes, Italy. The basaltic melts were equilibrated at 1,200°C with pure water, under oxidized conditions, and at pressures ranging from 163 to 3,842 bars. Our results show that at pressures above 1 kbar, alkali basalts dissolve more water than typical mid-ocean ridge basalts (MORB). Combination of our data with those from previous studies allows the following simple empirical model for the water solubility of basalts of varying alkalinity and fO2 to be derived: $$ {\text{H}}_{ 2} {\text{O}}\left( {{\text{wt}}\% } \right) = {\text{ H}}_{ 2} {\text{O}}_{\text{MORB}} \left( {{\text{wt}}\% } \right) + \left( {5.84 \times 10^{ - 5} *{\text{P}} - 2.29 \times 10^{ - 2} } \right) \times \left( {{\text{Na}}_{2} {\text{O}} + {\text{K}}_{2} {\text{O}}} \right)\left( {{\text{wt}}\% } \right) + 4.67 \times 10^{ - 2} \times \Updelta {\text{NNO}} - 2.29 \times 10^{ - 1} $$ where H2OMORB is the water solubility at the calculated P, using the model of Dixon et al. (1995). This equation reproduces the existing database on water solubilities in basaltic melts to within 5%. Interpretation of the speciation data in the context of the glass transition theory shows that water speciation in basalt melts is severely modified during quench. At magmatic temperatures, more than 90% of dissolved water forms hydroxyl groups at all water contents, whilst in natural or synthetic glasses, the amount of molecular water is much larger. A regular solution model with an explicit temperature dependence reproduces well-observed water species. Derivation of the partial molar volume of molecular water using standard thermodynamic considerations yields values close to previous findings if room temperature water species are used. When high temperature species proportions are used, a negative partial molar volume is obtained for molecular water. Calculation of the partial molar volume of total water using H2O solubility data on basaltic melts at pressures above 1 kbar yields a value of 19 cm3/mol in reasonable agreement with estimates obtained from density measurements.

Published
2011

177. Experimental determination of electrical conductivity during deformation of melt-bearing olivine aggregates: Implications for electrical anisotropy in the oceanic low velocity zone

Author

Julian Mecklenburgh, Emmanuel Le Trong, Luca Caricchi, Fabrice Gaillard, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], University of Bristol [Bristol], School of Earth, University of Manchester [Manchester], ANR-05-JCJC-0019,ELECTROVOLC,Mesures expérimentales des propriétés électriques et sismiques des magmas et de leur zone source(2005), and Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Torsion (mechanics), Mineralogy, anisotropy, Conductivity, 010502 geochemistry & geophysics, Thermal conduction, 01 natural sciences, Deformation and electrical conductivity, Simple shear, Geophysics, Shear (geology), Space and Planetary Science, Geochemistry and Petrology, Electrical resistivity and conductivity, Earth and Planetary Sciences (miscellaneous), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Low-velocity zone, Composite material, Anisotropy, Geology, 0105 earth and related environmental sciences, Lithosphere-Asthenosphere Boundary
Abstract

International audience; A novel experimental setup was used to measure in-situ variations of electrical conductivity (EC) during deformation in torsion (simple shear) at 300 MPa confining pressure and temperatures between 873 and 1473 K. This setup is designed to test if deformation of partially molten systems can produce electrical anisotropy. The motivation for this study comes from the observation that the Lithosphere–Asthenosphere Boundary (LAB) at mid-ocean ridges and in particular at the East Pacific Rise is strongly electrically anisotropic. In an initial set of calibration experiments, the variation of EC with temperature (873–1473 K) was determined for Carrara marble, Åheim dunite and basalt-bearing olivine aggregates. EC was then monitored during deformation experiments at 1473 K and measured in the frequency range between 6 MHz and 1 Hz. The electrical response of the different materials tested as a function of frequency, changes significantly depending on the presence, absence, proportion and distribution of melt contained in the specimen. Melt-free samples show a single conduction mechanism whereas melt-bearing samples display two conduction mechanisms linked in series, reflecting the contribution of isolated and connected melt. Impedance was measured along the sample radius, in a direction parallel to the shear gradient inherent in torsion experiments. During the tests, increasing values of the impedance measured suggest that the long range melt connectivity decreases radially, and melt drains from low to high shear stress regions. The conductivity, calculated from impedance measurements, is low and comparable to values measured along mid-ocean ridges. We suggest that electrical anisotropy of the LAB reflects an alternation of melt-enriched and melt-depleted channels elongated in the spreading direction possibly induced by spreading velocity gradients along the ridge. This implies that the observed electrical anisotropy reveals larger scale processes than strain-induced generation of crystallographic preferred orientations. Such large-scale processes could influence the distribution of seamounts and chemical variations of mid-ocean ridge basalts.

Published
2011

178. Constraining predictions of the carbon cycle using data

Author

Thomas Kaminski, E. N. Koffi, Peter Rayner, Jean-Louis Dufresne, Marko Scholze, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), School of Earth Sciences [Bristol], University of Bristol [Bristol], Fastopt GmbH, D-20357 Hamburg, Germany, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-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), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
010504 meteorology & atmospheric sciences, Climate Change, General Mathematics, General Physics and Astronomy, Climate change, 010502 geochemistry & geophysics, Atmospheric sciences, History, 21st Century, Models, Biological, 01 natural sciences, Sink (geography), Carbon Cycle, Carbon cycle, Physics::Geophysics, chemistry.chemical_compound, Data assimilation, Ecosystem, Water content, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, General Engineering, Linear model, Carbon Dioxide, chemistry, 13. Climate action, Data Interpretation, Statistical, Carbon dioxide, Linear Models, Environmental science, Forecasting
Abstract

We use a carbon-cycle data assimilation system to estimate the terrestrial biospheric CO 2 flux until 2090. The terrestrial sink increases rapidly and the increase is stronger in the presence of climate change. Using a linearized model, we calculate the uncertainty in the flux owing to uncertainty in model parameters. The uncertainty is large and is dominated by the impact of soil moisture on heterotrophic respiration. We show that this uncertainty can be greatly reduced by constraining the model parameters with two decades of atmospheric measurements.

Published
2011

179. How can land-use modelling tools inform bioenergy policies?

Author

Sarah Davis, Andras Molnar, Rocio Diaz-Chavez, Evan H. DeLucia, Joanna Isobel House, Hugo Valin, Energy Biosci Inst, Dept Plant Biol, University of Illinois System, School of Earth Sciences [Bristol], University of Bristol [Bristol], Ctr Environm Policy, Imperial College of Science, Economie Publique (ECO-PUB), AgroParisTech-Institut National de la Recherche Agronomique (INRA), and Institut National de la Recherche Agronomique (INRA)-AgroParisTech

Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences, MISCANTHUS, AGRICULTURE, Natural resource economics, 020209 energy, Biomedical Engineering, Biophysics, Biomass, Bioengineering, 02 engineering and technology, 010501 environmental sciences, 7. Clean energy, 01 natural sciences, Biochemistry, 12. Responsible consumption, Ecosystem services, Biomaterials, ENERGY, ORGANIC-CARBON, Bioenergy, BENEFITS, 0202 electrical engineering, electronic engineering, information engineering, Production (economics), feedstocks, SWITCHGRASS, indirect land-use change, 0105 earth and related environmental sciences, 2. Zero hunger, GREENHOUSE-GAS EMISSIONS, CLIMATE-CHANGE, Land use, business.industry, Environmental resource management, Energy security, Articles, 15. Life on land, biofuels, NITROGEN, 13. Climate action, greenhouse gas, Greenhouse gas, BIOFUEL FEEDSTOCK, environmental economics, Business, ecosystem services, Externality, Biotechnology
Abstract

Targets for bioenergy have been set worldwide to mitigate climate change. Although feedstock sources are often ambiguous, pledges in European nations, the United States and Brazil amount to more than 100 Mtoe of biorenewable fuel production by 2020. As a consequence, the biofuel sector is developing rapidly, and it is increasingly important to distinguish bioenergy options that can address energy security and greenhouse gas mitigation from those that cannot. This paper evaluates how bioenergy production affects land-use change (LUC), and to what extent land-use modelling can inform sound decision-making. We identified local and global internalities and externalities of biofuel development scenarios, reviewed relevant data sources and modelling approaches, identified sources of controversy about indirect LUC (iLUC) and then suggested a framework for comprehensive assessments of bioenergy. Ultimately, plant biomass must be managed to produce energy in a way that is consistent with the management of food, feed, fibre, timber and environmental services. Bioenergy production provides opportunities for improved energy security, climate mitigation and rural development, but the environmental and social consequences depend on feedstock choices and geographical location. The most desirable solutions for bioenergy production will include policies that incentivize regionally integrated management of diverse resources with low inputs, high yields, co-products, multiple benefits and minimal risks of iLUC. Many integrated assessment models include energy resources, trade, technological development and regional environmental conditions, but do not account for biodiversity and lack detailed data on the location of degraded and underproductive lands that would be ideal for bioenergy production. Specific practices that would maximize the benefits of bioenergy production regionally need to be identified before a global analysis of bioenergy-related LUC can be accomplished.

Published
2011

180. Application of time resolved x-ray diffraction to study the solidification of glass-forming melts

Author

Louis HENNET, Pozdnyakova, I., Bytchkov, A., Drewitt, J. W. E., Kozaily, J., Leydier, M., Brassamin, S., Zanghi, D., Fischer, H. E., Greaves, G. N., Price, D. L., Hennet, Louis, Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Amphenol NovaSensor, Dutch-Belgian Beamline DUBBLE at the ESRF, Grenoble, School of Earth Sciences [Bristol], University of Bristol [Bristol], Institut Laue-Langevin (ILL), ILL, and Aberystwyth University

Subjects
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], ComputingMilieux_MISCELLANEOUS, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]
Abstract

International audience

Published
2011

181. Eruption of Soufrière Hills (1995–2009) from an offshore perspective: Insights from repeated swath bathymetry surveys

Author

Le Friant, A., Deplus, C., Boudon, G., Feuillet, N., Trofimovs, J., Komorowski, J.-C., Sparks, R.S.J., Talling, P., Loughlin, S., Palmer, M., Ryan, G., Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), National Oceanography Centre [Southampton] (NOC), University of Southampton, School of Earth Sciences [Bristol], University of Bristol [Bristol], National Oceanography Center, British Geological Survey [Edinburgh], British Geological Survey (BGS), Institute of Earth Science and Engineering, University of Auckland [Auckland], and 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
[SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract

International audience; This contribution provides an analysis of the 1995–2009 eruptive period of Soufrière Hills volcano (Montserrat) from a unique offshore perspective. The methodology is based on five repeated swath bathymetric surveys. The difference between the 2009 and 1999 bathymetry suggests that at least 395 Mm3 of material has entered the sea. This proximal deposit reaches 95 m thick and extends ∼7km from shore. However, the difference map does not include either the finer distal part of the submarine deposit or the submarine part of the delta close to the shoreline. We took both contributions into account by using additional information such as that from marine sediment cores. By March 2009, at least 65% of the material erupted throughout the eruption has been deposited into the sea. This work provides an excellent basis for assessing the future activity of the Soufrière Hills volcano (including potential collapse), and other volcanoes on small islands.

Published
2010

182. Dyke propagation and sill formation in a compressive tectonic environment

Author

P. Benghiat, Thierry Menand, Katherine A. Daniels, School of Earth Sciences [Bristol], and University of Bristol [Bristol]

Subjects
Atmospheric Science, Buoyancy, 010504 meteorology & atmospheric sciences, Soil Science, Aquatic Science, engineering.material, 010502 geochemistry & geophysics, Oceanography, Rotation, 01 natural sciences, Stress (mechanics), dyke arrest, Sill, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), medicine, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Compression (geology), 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology, geography, geography.geographical_feature_category, Ecology, Fissure, compressive stress, Paleontology, Forestry, Tectonics, Geophysics, medicine.anatomical_structure, Compressive strength, Space and Planetary Science, engineering, sill emplacement, Geology, Seismology
Abstract

International audience; Sills could potentially form as a result of dykes modifying their trajectory in response to remote tectonic compression. Here, we use analogue experiments to investigate how a buoyant vertical dyke adjusts its trajectory to a compressive remote stress to form a sill, and over which vertical distance this sill formation does occur. Our investigation is restricted to an intrusion propagating through a homogeneous solid, which enables us to identify the characteristic length-scale over which a dyke responds to remote stress compression, independently of the presence of crustal layers. The experiments involve the injection of air in a gelatine solid that experiences lateral deviatoric compression. The response of the buoyant air crack to the compressive stress in not instantaneous but operates over some distance. An important observation is that some cracks reach the surface despite the compressive environment. Dyke-to-sill rotation occurs only for large compressive stress or small effective buoyancy. Dimensional analysis shows that the length-scale over which this rotation takes place increases exponentially with the ratio of crack effective buoyancy to horizontal compressive stress. Up-scaled to geological conditions, our analysis indicates that a dyke-to-sill transition in response to tectonic compression in homogeneous rocks cannot occur over less than two hundred meters and would need several kilometers in most cases. This is typically greater than the average thickness of lithological units, which supports the idea that crustal heterogeneities play an important role in determining the fate of dykes and in controlling where sills could form.

Published
2010

183. Tree trunks of Pitus primaeva in Mississippian (Courceyan) rocks at Montford, near Rothesay, Isle of Bute, Scotland

Author

Elsa Henderson, Jean Galtier, Howard J. Falcon-Lang, School of Earth Sciences [Bristol], University of Bristol [Bristol], Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD [France-Sud]), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])

Subjects
010506 paleontology, Plant Anatomy, Water stress, Geology, Ecological succession, Seasonality, 010502 geochemistry & geophysics, medicine.disease, 01 natural sciences, Paleontology, Palaeobotany : Tree trunk, Laurasia, Pitus primaeva, medicine, Plant fossil, [SDE.BE.EVO]Environmental Sciences/Biodiversity and Ecology/domain_sde.be.evo, Tree (set theory), Mississippian, 0105 earth and related environmental sciences
Abstract

A-10-15; International audience; Silicified tree trunks are described for the first time from Montford, near Rothesay, Isle of Bute, Scotland. The fossils occur in a fault-bounded succession, which is probably part of the Mississippian (Courceyan) Kinnesswood Formation. Quantitative anatomical analysis indicates that the tree trunks belong to the arborescent pteridosperm, Pitus primaeva Witham. Growth interruptions preserved in branches imply that these trees experienced aperiodic water stress, perhaps reflecting monsoonal seasonality in this part of palaeoequatorial Laurasia

Published
2010

184. Anatomically-preserved tree-trunks in late Mississippian (Serpukhovian, late Pendleian-Arnsbergian) braided fluvial channel facies, near Searston, southwest Newfoundland, Canada

Author

Jean Galtier, Howard J. Falcon-Lang, School of Earth Sciences [Bristol], University of Bristol [Bristol], Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD [France-Sud]), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])

Subjects
010506 paleontology, Fluvial, 010502 geochemistry & geophysics, Serpukhovian, 01 natural sciences, Paleontology, Carboniferous, Progymnosperm, [SDE.BE.EVO]Environmental Sciences/Biodiversity and Ecology/domain_sde.be.evo, braided fluvial, Ecology, Evolution, Behavior and Systematics, fossil wood, 0105 earth and related environmental sciences, Palynology, biology, 15. Life on land, biology.organism_classification, Newfoundland, pteridosperm, Facies, Paleobotany, Fossil wood, Pitus, tree-rings, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology, Mississippian
Abstract

A-10-14; International audience; Little is known of the Mississippian palaeobotany of Newfoundland, Canada. Here we improve this situation by describing anatomically-preserved tree-trunks from the Codroy Valley, southwest Newfoundland. The tree-trunks, which have incomplete lengths of up to 8.3 m, occur in braided fluvial channel facies of the Searston Formation, a late Pendleian-Arnsbergian (upper Serpukhovian, 326.4-325 Ma) unit. Three morphotypes are present. The first, Pitus primaeva Witham shows exceptionally wide rays (1-8-seriate, rarely to 16-seriate) and tracheids with multiseriate pits. The second, cf. Pitus withamii (Lindley and Hutton) Witham has rather narrower rays (1-3-seriate), and unusually shows ray cells pitted on all walls. Both morphotypes probably represent arborescent pteridosperms. The third, Protopitys scotica Walton is characterized by the occurrence of very short rays (mode: 1 cell high), and represents a putative progymnosperm. Associated megafloral assemblages are dominated by Diplotmema and Adiantites, which may have comprised the foliage of the lignophytes described herein. However, in marked contrast, palynological assemblages suggest that arborescent lycopsids, sphenopsids and ferns dominated regional vegetation make-up. One resolution to this paradox is the lignophytes may have been growing on levees or well-drained uplands to the south, and washed into the basin in river channels, while pteridophytic vegetation occupied the floodplain. This inference is supported by occurrence of irregular growth interruptions in the fossil woods, suggesting trees grew under a seasonally dry tropical climate

Published
2010

185. Rheological control on the dynamics of explosive activity in the 2000 summit eruption of Mt. Etna

Author

Daniele Giordano, Paolo Papale, Margherita Polacci, Luca Caricchi, Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, School of Earth Sciences [Bristol], University of Bristol [Bristol], Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), POTHIER, Nathalie, and Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Lava, Stratigraphy, [SDE.MCG]Environmental Sciences/Global Changes, Soil Science, 010502 geochemistry & geophysics, 01 natural sciences, law.invention, Crystal, Viscosity, Impact crater, lcsh:Stratigraphy, Geochemistry and Petrology, law, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Crystallization, Petrology, Earth-Surface Processes, lcsh:QE640-699, 0105 earth and related environmental sciences, Vulcanian eruption, lcsh:QE1-996.5, Paleontology, Geology, Geophysics, Strombolian eruption, lcsh:Geology, [SDE.MCG] Environmental Sciences/Global Changes, 13. Climate action, Magma, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract

In the period from January to June 2000 Mt. Etna exhibited an exceptional explosive activity characterized by a succession of 64 Strombolian and fire-fountaining episodes from the summit South-East Crater. Textural analysis of the eruptive products reveals that the magma associated with the Strombolian phases had a much larger crystal content (>55 vol%) with respect to the magma discharged during the fire-fountain phases (~35 vol%). Rheological modelling shows that the crystal-rich magma falls in a region beyond a critical crystal content where small addition of solid particles causes an exponential increase of the effective magma viscosity. When implemented into the modeling of steady magma ascent dynamics (as assumed for the fire-fountain activity), a large crystal content as the one found for products of Strombolian eruption phases results in a one order of magnitude decrease of mass flow-rate, and in the onset of conditions where small heterogeneities in the solid fraction carried by the magma translate into highly unsteady eruption dynamics. We argue that crystallization on top of the magmatic column during the intermediate phases when magma was not discharged favoured conditions corresponding to Strombolian activity, with fire-fountain activity resuming after removal of the highly crystalline top. The numerical simulations also provide a consistent interpretation of the association between fire-fountain activity and emergence of lava flows from the crater flanks.

Published
2010

186. On the formation of high-latitude soil carbon stocks: Effects of cryoturbation and insulation by organic matter in a land surface model

Author

Charles D. Koven, Gerhard Krinner, Philippe Ciais, D. Khvorostyanov, Charles Tarnocai, Pierre Friedlingstein, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), School of Earth Sciences [Bristol], University of Bristol [Bristol], ICOS-ATC (ICOS-ATC), 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, 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 Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), 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 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), Agriculture and Agri-Food [Ottawa] (AAFC), supported by CEA, ANR-06-VULN-0011,IMPACT-BOREAL,IMPACT of climate on hydrology and methane production in anaerobic soils in BOREAL regions(2006), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), 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)-Centre National de la Recherche Scientifique (CNRS), ANR: project Impact-Boreal,project Impact-Boreal, 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)-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), 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), 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), and Agriculture and Agri-Food (AAFC)

Subjects
Hydrology, global carbon cycle, 010504 meteorology & atmospheric sciences, Soil organic matter, 0207 environmental engineering, Yedoma, Soil classification, Soil science, 02 engineering and technology, Soil carbon, 15. Life on land, Permafrost, 01 natural sciences, Carbon cycle, climate change, Geophysics, 13. Climate action, Soil water, General Earth and Planetary Sciences, Environmental science, Permafrost carbon cycle, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, 020701 environmental engineering, permafrost, 0105 earth and related environmental sciences
Abstract

International audience; We modify the soil component of the ORCHIDEE terrestrial carbon cycle model to include vertically-discretized soil carbon. With this model, we investigate the feedback of considering thermal insulation by soil carbon, which modifies the soil thermal regime by lowering the thermal conductivity and increasing the heat capacity of a carbon-rich soil, on the total carbon stocks the model builds up. In addition, we demonstrate the effects of diffusive vertical mixing of soil organic matter by cryoturbation on the total carbon stocks that the model builds up in mineral soils in equilibrium with a steady climate. We show that including these two effects together leads to up to 30% higher soil carbon stocks in the top meter of permafrost soils, as well as large stocks of carbon below 1m in the upper permafrost soil layers. The vertical profile of partitioning of carbon between different lability pools is also affected, as the slower pools are more deeply mixed; also the time to reach equilibrium lengthens considerably. These effects are largest in the coldest regions such as Eastern Siberia. The inclusion of cryoturbative mixing and insulation by soil carbon leads to better agreement with estimates of high-latitude soil carbon stocks, where substantial amounts of carbon are found in permafrost regions, to depths of three meters; however we do not include peat, Yedoma, or alluvial deposition processes here, so the total carbon stocks are still lower than observed.

Published
2009

187. Lower crustal earthquakes near the Ethiopian rift induced by magmatic processes

Author

Keir, D., Bastow, Id, Whaler, Ka, Daly, E., Dg, Cornwell, Hautot, Sophie, School of Earth and Environment [Leeds] (SEE), University of Leeds, School of Earth Sciences [Bristol], University of Bristol [Bristol], Grant Institute, School of GeoSciences, University of Edinburgh, Department of Earth and Ocean Sciences [Galway], National University of Ireland [Galway] (NUI Galway), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), and Université européenne de Bretagne - European University of Brittany (UEB)

Subjects
Geochemistry & Geophysics, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, CONTINENTAL RIFTS, Science & Technology, 02 Physical Sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], BENEATH, [SDE.MCG]Environmental Sciences/Global Changes, lower crust, magma, 04 Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], rift, THERMAL STRUCTURE, EVOLUTION, Afar, V-P/V-S, LITHOSPHERE, AFRICAN EARTHQUAKES, earthquake, Physical Sciences, EAST-AFRICA, FOCAL DEPTHS, Ethiopia, Earthquake, Lower crust, Magma, Rift, Geophysics, Geochemistry and Petrology
Abstract

International audience; Lower crustal earthquakes are commonly observed in continental rifts at depths where temperatures should be too high for brittle failure to occur. Here we present accurately located earthquakes in central Ethiopia, covering an incipient oceanic plate boundary in the Main Ethiopian Rift. Seismicity is evaluated using the combination of exceptionally well resolved seismic structure of the crust and upper mantle, electromagnetic properties of the crust, rock geochemistry, and geological data. The combined data sets provide evidence that lower crustal earthquakes are focused in mafic lower crust containing pockets of the largest fraction of partial melt. The pattern of seismicity and distribution of crustal melt also correlates closely with presence of partial melt in the upper mantle, suggesting lower crustal earthquakes are induced by ongoing crustal modification through magma emplacement that is driven by partial melting of the mantle. Our results show that magmatic processes control not only the distribution of shallow seismicity and volcanic activity along the axis of the rift valley but also anomalous earthquakes in the lower crust away from these zones of localized strain.

Published
2009

188. Modeling the flow of basaltic magma into subsurface nuclear facilities

Author

Menand, Thierry, Phillips, Jeremy C., Sparks, R. Stephen J., Woods, Andrew, School of Earth Sciences [Bristol], University of Bristol [Bristol], BP institute for Multiphase Flow [Cambrige], University of Cambridge [UK] (CAM), Charles B. Connor, Neil A. Chapman, Laura J. Connor, Menand, Thierry, and Charles B. Connor, Neil A. Chapman, Laura J. Connor

Subjects
[SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2009

189. Footprint of temperature changes in the temperate and boreal forest carbon balance

Author

Peylin, Philippe, Piao, Shilong, Friedlingstein, P., Ciais, Philippe, Zhu, B., Reichstein, M., College of Urban and Environmental Sciences [Beijing], Peking University [Beijing], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), School of Earth Sciences [Bristol], University of Bristol [Bristol], ICOS-ATC (ICOS-ATC), 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), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), University of California, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, 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-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Dynamique de la Biodiversité (LADYBIO), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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), 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), and University of California (UC)

Subjects
[SDE]Environmental Sciences
Abstract

International audience; In this study, we use net ecosystem productivity (NEP) measurement data across several forest sites and a simple conceptual model to investigate the linkage between temperature and NEP by considering either temperature change in the recent past or current mean annual temperature (MAT) as a forcing. After removing the effect of stand age, forest NEP is only weakly correlated with MAT. However, temperature changes during the period of 1980-2002 do explain a very significant fraction of the current spatial patterns of NEP, although the response of the terrestrial carbon balance to temperature changes varies with season. Changes in spring temperature having the highest correlation with annual NEP. We also show that temperature changes before the 1970s had a limited influence on the current NEP, and that the impact of recent temperature changes within the last decade on NEP are not strong enough to be observable. Overall, our analysis indicates not only that temperature changes in the recent past is one of the important drivers of today's forest carbon balance in the Northern Hemisphere, but also that the ongoing global warming will contribute significantly to the near-future evolution of the Northern Hemisphere carbon sink. A non-equilibrium framework must be taken into account when studying the impacts of temperature change on current or future forest net carbon balance.

Published
2009

190. Comparing crustal and mantle fabric from the North American craton using magnetics and seismic anisotropy

Author

Andreas Wüstefeld, Götz Bokelmann, Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), School of Earth Sciences [Bristol], and University of Bristol [Bristol]

Subjects
Seismic anisotropy, 010504 meteorology & atmospheric sciences, magnetics, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Geochemistry and Petrology, Lithosphere, Earth and Planetary Sciences (miscellaneous), 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Crustal recycling, seismic anisotropy, Shear wave splitting, Crust, Geophysics, fabrics, Craton, Space and Planetary Science, lithosphere, shear-wave splitting, Geology, Seismology
Abstract

International audience; A central target in Earth sciences is the study of deformation at various depth levels within the Earth. Seismology has offered a remarkable tool for doing this via seismic anisotropy. It is however not always clear how to interpret those observations. A question of interest is to understand the relation between the deformation of the mantle and the crust, and in studying the relation between the two. Mantle deformation is expressed in seismic anisotropy. In this paper we seek an objective way of extracting information about crustal fabric as well, to be able to compare with seismic anisotropy. The magnetization of crustal rocks offers an attractive possibility for doing this. We thus explore the use of magnetic data, and we compare magnetic crustal fabric orientation with mantle fabric observations from seismic anisotropy. We apply our technique to the North American craton for which we have an excellent magnetic dataset, and we show that there is a clear relation between crustal and mantle fabric for the cratonic region. This has important implications for crustal formation, and for interpreting seismic anisotropy observations.

Published
2009

191. Circulation of bubbly magma and gas segregation within tunnels of the potential Yucca Mountain repository

Author

R. Stephen J. Sparks, Thierry Menand, Jeremy C. Phillips, School of Earth Sciences [Bristol], and University of Bristol [Bristol]

Subjects
Convection, Buoyancy, 010504 meteorology & atmospheric sciences, Mineralogy, Magma chamber, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Strombolian eruption, Viscosity, Flux (metallurgy), Volume (thermodynamics), 13. Climate action, Geochemistry and Petrology, Magma, engineering, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Petrology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Following an intersection of rising magma with drifts of the potential Yucca Mountain nuclear waste repository, a pathway is likely to be established to the surface with magma flowing for days to weeks and affecting the performance of engineered structures located along or near the flow path. In particular, convective circulation could occur within magma-filled drifts due to the exsolution and segregation of magmatic gas. We investigate gas segregation in a magma-filled drift intersected by a vertical dyke by means of analogue experiments, focusing on the conditions of sustained magma flow. Degassing is simulated by electrolysis, producing micrometric bubbles in viscous mixtures of water and golden syrup, or by aerating golden syrup, producing polydisperse bubbly mixtures with 40% of gas by volume. The presence of exsolved bubbles induces a buoyancy-driven exchange flow between the dyke and the drift that leads to gas segregation. Bubbles segregate from the magma by rising and accumulating as a foam at the top of the drift, coupled with the accumulation of denser degassed magma at the base of the drift. Steady-state influx of bubbly magma from the dyke into the drift is balanced by outward flux of lighter foam and denser degassed magma. The length and time scales of this gas segregation are controlled by the rise of bubbles in the horizontal drift. Steady-state gas segregation would be accomplished within hours to hundreds of years depending on the viscosity of the degassed magma and the average size of exsolved gas bubbles, and the resulting foam would only be a few cm thick. The exchange flux of bubbly magma between the dyke and the drift that is induced by gas segregation ranges from 1 m3 s−1, for the less viscous magmas, to 10−8 m3 s−1, for the most viscous degassed magmas, with associated velocities ranging from 10−1 to 10−9 m s−1 for the same viscosity range. This model of gas segregation also predicts that the relative proportion of erupted degassed magma, that could potentially carry and entrain nuclear waste material towards the surface, would depend on the value of the dyke magma supply rate relative to the value of the gas segregation flux, with violent eruption of gassy as well as degassed magmas at relatively high magma supply rates, and eruption of mainly degassed magma by milder episodic Strombolian explosions at relatively lower supply rates.

Published
2008

192. The mechanics and dynamics of sills in layered elastic rocks and their implications for the growth of laccoliths and other igneous complexes

Author

Thierry Menand, School of Earth Sciences [Bristol], and University of Bristol [Bristol]

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Pluton, Dynamics (mechanics), Rigidity (psychology), Geophysics, Classification of discontinuities, 010502 geochemistry & geophysics, 01 natural sciences, Laccolith, Igneous rock, Sill, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Anisotropy, Petrology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

The recent experimental work by Kavanagh et al. [Kavanagh, J.L., Menand, T. and Sparks, R.S.J. (2006). An experimental investigation of sill formation and propagation in layered elastic media. Earth Planet. Sci. Lett. 245, 799–813.] shows that lithological discontinuities and rigidity contrasts can control the formation and dynamics of sills at interfaces separating upper, rigid strata from lower, weaker strata. The present paper extends this work and focuses on its implications in terms of the length- and time-scales associated with the development of laccoliths and other igneous complexes. Sill formation controlled by rigidity contrasts is shown to provide a growth mechanism for laccoliths. The formation of a sill provides favourable rigidity anisotropy for the emplacement of subsequent sills so that laccoliths grow by over-accretion, under-accretion or even mid-accretion of successive sills. In accord with field data, this model predicts that laccoliths grow mainly by vertical expansion, representing the cumulative thickness of their internal sills, while maintaining a comparatively constant lateral extend. The model also predicts that the time-scale over which laccoliths form is essentially determined by the cumulative time between successive sill intrusions. Also, sill dynamics are controlled by viscous dissipation of the fluid along their length, which have consequences for the size and shape of sills. Viscously-controlled dynamics would enable sills to propagate further and thus to grow thicker than dykes of similar magmas. These dynamics would also enable sills to propagate faster and thus to induce non-elastic deformations in surrounding rocks that could deviate them from the interface they originally follow. This would allow them to feed new sills along other interfaces and could assist in the formation of the step structures and saucer-shapes that are commonly observed in sill complexes.

Published
2008

193. Orbital and millennial-scale features of atmospheric CH4 over the past 800,000 years

Author

Jérôme Chappellaz, Dominique Raynaud, Thomas F. Stocker, Renato Spahni, Jean-Marc Barnola, L. Loulergue, Bénédicte Lemieux, Valérie Masson-Delmotte, Thomas Blunier, Adrian Schilt, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), 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)-Centre National de la Recherche Scientifique (CNRS), Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern]-Universität Bern [Bern], Centre for Ice and Climate [Copenhagen], Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), School of Earth Sciences [Bristol], University of Bristol [Bristol], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL), École normale supérieure - Paris (ENS Paris)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), 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 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), 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), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), 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), 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), Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), 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), and 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)

Subjects
spectroscopy, glacier, 010504 meteorology & atmospheric sciences, oxidation, Climate change, source sink relationship, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, tropic climate, Methane, chemistry.chemical_compound, atmospheric pressure, Ice core, Paleoclimatology, atmospheric gas, paleoclimate, Glacial period, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, isotope, paleoatmosphere, 0105 earth and related environmental sciences, Multidisciplinary, Atmospheric methane, methane, glacial-interglacial cycle, article, greenhouse effect, 15. Life on land, spectral analysis, ice sheet, wetland, air temperature, Oceanography, climate change, chemistry, priority journal, 13. Climate action, greenhouse gas, Greenhouse gas, ice core record, Interglacial, Environmental science, Antarctica, ice core
Abstract

Atmospheric methane is an important greenhouse gas and a sensitive indicator of climate change and millennial-scale temperature variability. Its concentrations over the past 650,000 years have varied between ∼350 and ∼800 parts per 109 by volume (p.p.b.v.) during glacial and interglacial periods, respectively. In comparison, present-day methane levels of ∼1,770 p.p.b.v. have been reported. Insights into the external forcing factors and internal feedbacks controlling atmospheric methane are essential for predicting the methane budget in a warmer world. Here we present a detailed atmospheric methane record from the EPICA Dome C ice core that extends the history of this greenhouse gas to 800,000 yr before present. The average time resolution of the new data is ∼380 yr and permits the identification of orbital and millennial-scale features. Spectral analyses indicate that the long-term variability in atmospheric methane levels is dominated by ∼100,000 yr glacial-interglacial cycles up to ∼400,000 yr ago with an increasing contribution of the precessional component during the four more recent climatic cycles. We suggest that changes in the strength of tropical methane sources and sinks (wetlands, atmospheric oxidation), possibly influenced by changes in monsoon systems and the position of the intertropical convergence zone, controlled the atmospheric methane budget, with an additional source input during major terminations as the retreat of the northern ice sheet allowed higher methane emissions from extending periglacial wetlands. Millennial-scale changes in methane levels identified in our record as being associated with Antarctic isotope maxima events are indicative of ubiquitous millennial-scale temperature variability during the past eight glacial cycles. ©2008 Nature Publishing Group.

Published
2008

194. Process-based estimates of terrestrial ecosystem isoprene emissions: incorporating the effects of a direct CO2-isoprene interaction

Author

Arneth, A., Niinemets, Ü., Pressley, S., Bäck, J., Hari, P., Karl, T., Noe, S., Prentice, I. C., Serça, Dominique, Hickler, T., Wolf, A., Smith, B., Department of Physical Geography and Ecosystems Analysis, Geobiosphere Science Centre, Department of Plant Physiology, Institute of Molecular and Cell Biology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences (EMU), University of Washington [Seattle], Forest Ecology and Management [Helsinki], Department of Forest Sciences [Helsinki], Faculty of Agriculture and Forestry [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Faculty of Agriculture and Forestry [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Atmospheric Chemistry Division [Boulder], National Center for Atmospheric Research [Boulder] (NCAR), QUEST [Bristol], School of Earth Sciences [Bristol], University of Bristol [Bristol]-University of Bristol [Bristol], Laboratoire d'aérologie (LAERO), 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), 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), Forest Ecology, University of Helsinki-University of Helsinki-Faculty of Agriculture and Forestry [Helsinki], University of Helsinki-University of Helsinki, 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), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract

International audience; In recent years evidence has emerged that the amount of isoprene emitted from a leaf is affected by the CO2 growth environment. Many – though not all – laboratory experiments indicate that emissions increase significantly at below-ambient CO2 concentrations and decrease when concentrations are raised to above-ambient. A small number of process-based leaf isoprene emission models can reproduce this CO2 stimulation and inhibition. These models are briefly reviewed, and their performance in standard conditions compared with each other and to an empirical algorithm. One of the models was judged particularly useful for incorporation into a dynamic vegetation model framework, LPJ-GUESS, yielding a tool that allows the interactive effects of climate and increasing CO2 concentration on vegetation distribution, productivity, and leaf and ecosystem isoprene emissions to be explored. The coupled vegetation dynamics-isoprene model is described and used here in a mode particularly suited for the ecosystem scale, but it can be employed at the global level as well. Annual and/or daily isoprene emissions simulated by the model were evaluated against flux measurements (or model estimates that had previously been evaluated with flux data) from a wide range of environments, and agreement between modelled and simulated values was generally good. By using a dynamic vegetation model, effects of canopy composition, disturbance history, or trends in CO2 concentration can be assessed. We show here for five model test sites that the suggested CO2-inhibition of leaf-isoprene metabolism can be large enough to offset increases in emissions due to CO2-stimulation of vegetation productivity and leaf area growth. When effects of climate change are considered atop the effects of atmospheric composition the interactions between the relevant processes will become even more complex. The CO2-isoprene inhibition may have the potential to significantly dampen the expected steep increase of ecosystem isoprene emission in a future, warmer atmosphere with higher CO2 levels; this effect raises important questions for projections of future atmospheric chemistry, and its connection to the terrestrial vegetation and carbon cycle.

Published
2007

195. Gas segregation in dykes and sills

Author

Jeremy C. Phillips, Thierry Menand, School of Earth Sciences [Bristol], and University of Bristol [Bristol]

Subjects
Basalt, geography, geography.geographical_feature_category, Buoyancy, 010504 meteorology & atmospheric sciences, Lava, Mineralogy, Volcanism, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Strombolian eruption, Geophysics, Volcano, Sill, Geochemistry and Petrology, Magma, engineering, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Petrology, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Many basaltic volcanoes emit a substantial amount of gas over long periods of time while erupting relatively little degassed lava, implying that gas segregation must have occurred in the magmatic system. The geometry and degree of connectivity of the plumbing system of a volcano control the movement of magma in that system and could therefore provide an important control on gas segregation in basaltic magmas. We investigate gas segregation by means of analogue experiments and analytical modelling in a simple geometry consisting of a vertical conduit connected to a horizontal intrusion. In the experiments, degassing is simulated by electrolysis, producing micrometric bubbles in viscous mixtures of water and golden syrup. The presence of exsolved bubbles induces a buoyancy-driven exchange flow between the conduit and the intrusion that leads to gas segregation. Bubbles segregate from the fluid by rising and accumulating as foam at the top of the intrusion, coupled with the accumulation of denser degassed fluid at the base of the intrusion. Steady-state influx of bubbly fluid from the conduit into the intrusion is balanced by outward flux of lighter foam and denser degassed fluid. The length and time scales of this gas segregation are controlled by the rise of bubbles in the horizontal intrusion. Comparison of the gas segregation time scale with that of the cooling and solidification of the intrusion suggests that gas segregation is more efficient in sills (intrusions in a horizontal plane with typical width:length aspect ratio 1:100) than in horizontally-propagating dykes (intrusions in a vertical plane with typical aspect ratio 1:1000), and that this process could be efficient in intermediate as well as basaltic magmas. Our investigation shows that non-vertical elements of the plumbing systems act as strong gas segregators. Gas segregation has also implications for the generation of gas-rich and gas-poor magmas at persistently active basaltic volcanoes. For low magma supply rates, very efficient gas segregation is expected, which induces episodic degassing activity that erupts relatively gas-poor magmas. For higher magma supply rates, gas segregation is expected to be less effective, which leads to stronger explosions that erupt gas-rich as well as gas-poor magmas. These general physical principles can be applied to Stromboli volcano and are shown to be consistent with independent field data. Gas segregation at Stromboli is thought likely to occur in a shallow reservoir of sill-like geometry at 3.5 km depth with exsolved gas bubbles 0.1–1 mm in diameter. Transition between eruptions of gas-poor, high crystallinity magmas and violent explosions that erupt gas-rich, low crystallinity magmas are calculated to occur at a critical magma supply rate of 0.1–1 m 3 s − 1 .

Published
2007

196. Experimental evidence for the formation of geomacromolecules from plant leaf lipids

Author

Richard D. Pancost, Derek E. G. Briggs, Raymond Michels, Richard P. Evershed, Margaret E. Collinson, Neal S. Gupta, Organic Geochemistry Unit - OGU (Bristol, United Kingdom), University of Bristol [Bristol], School of Earth Sciences [Bristol], Department of Geology and Geophysics (DGG), Yale University [New Haven], Géologie et gestion des ressources minérales et énergétiques (G2R), Université Henri Poincaré - Nancy 1 (UHP)-Institut National Polytechnique de Lorraine (INPL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Centre National de la Recherche Scientifique (CNRS), Department of Geology (DG), and Royal Holloway [University of London] (RHUL)

Subjects
chemistry.chemical_classification, 010506 paleontology, 010502 geochemistry & geophysics, 01 natural sciences, Plant tissue, chemistry.chemical_compound, chemistry, Biochemistry, Geochemistry and Petrology, Kerogen, Organic chemistry, Organic matter, Alkyl, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Macromolecule
Abstract

Experimental maturation of plant tissue (350 °C, 700 bar) generates a resistant non-hydrolysable aliphatic macromolecule similar to that comprising organic matter in ancient sediments (kerogen). Comparison of the products derived from maturation of different pre-treated plant tissues clearly demonstrates that solvent-extractable and hydrolysable lipids are precursors of the generated macromolecular material. Thus, the experiments indicate that labile alkyl compounds can be a source of the insoluble aliphatic component of fossil organic matter and kerogen in the absence of a resistant aliphatic precursor (e.g. cutan) in the living organism.

Published
2007

197. Evidence for the in-situ polymerisation of labile aliphatic organic compounds during the preservation of fossil leaves : implications for organic matter preservation

Author

Richard D. Pancost, Derek E. G. Briggs, Margaret E. Collinson, Richard P. Evershed, Raymond Michels, Kevin S. Jack, Neal S. Gupta, Organic Geochemistry Unit - OGU (Bristol, United Kingdom), University of Bristol [Bristol], School of Earth Sciences [Bristol], Department of Geology and Geophysics (DGG), Yale University [New Haven], Department of Geology (DG), Royal Holloway [University of London] (RHUL), Géologie et gestion des ressources minérales et énergétiques (G2R), Université Henri Poincaré - Nancy 1 (UHP)-Institut National Polytechnique de Lorraine (INPL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Centre National de la Recherche Scientifique (CNRS), and Bristol Colloid Centre (BCC)

Subjects
chemistry.chemical_classification, 010506 paleontology, Wax, Cuticle, food and beverages, Fatty acid, Cutin, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, chemistry, Geochemistry and Petrology, visual_art, Kerogen, visual_art.visual_art_medium, Organic chemistry, Lignin, lipids (amino acids, peptides, and proteins), Organic matter, Chemical decomposition, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Organic matter preservation is typically attributed to selective preservation of resistant biomolecules, random polymerisation of diagenetically degraded biomolecules (i.e. neogenesis) or in situ polymerisation of labile aliphatic components (in the case of fossil plants and insects). To evaluate these processes, we investigated the morphology and chemical structure of fossil leaves from the Arde`che diatomite (Late Miocene, southeast France) and compared them to their modern equivalents. Chemical analyses of the fossil leaves revealed the presence of a recalcitrant (non-hydrolysable) geopolymer comprised of benzene derivatives, lignin-derived components, pristenes and an aliphatic component; the latter consists partly of fatty acyl subunits ranging in carbon number from C8 to C32 with an abundance of C16 and C18 units. Chemical degradation of the modern plants failed to reveal the presence of the aliphatic biomacromolecule cutan, thereby precluding selective preservation of this compound as the source for the aliphatic component of the fossil leaves. In contrast, C16 and C18 fatty acyl units are predominant in the cutin and phospholipid fatty acid (PLFA) fractions of the modern leaves, while C10 to C32 acid units are characteristic of the free fatty acid (FA) fraction of epicuticular waxes. However, TEM and SEM investigations of the fossils revealed no evidence for cuticle preservation, and while a contribution from cutin cannot be excluded, the aliphatic component of the fossil polymer is possibly derived instead from the in situ polymerisation of labile cell membrane lipids and free fatty acids. A similar process involving lipid polymerisation has been observed previously in kerogen formation alongside selective preservation and, hence, may be important in organic matter preservation.

Published
2007

198. Molecular preservation of plant and insect cuticles from the oligocene enspel formation, Germany : evidence against derivation of aliphatic polymer from sediment

Author

Richard P. Evershed, Raymond Michels, Richard D. Pancost, Derek E. G. Briggs, Neal S. Gupta, Margaret E. Collinson, Organic Geochemistry Unit - OGU (Bristol, United Kingdom), University of Bristol [Bristol], School of Earth Sciences [Bristol], Department of Geology and Geophysics (DGG), Yale University [New Haven], Department of Geology (DG), Royal Holloway [University of London] (RHUL), Géologie et gestion des ressources minérales et énergétiques (G2R), and Université Henri Poincaré - Nancy 1 (UHP)-Institut National Polytechnique de Lorraine (INPL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
chemistry.chemical_classification, 010506 paleontology, Taphonomy, Cuticle, fungi, chemistry.chemical_element, Sediment, Biology, 010502 geochemistry & geophysics, Polysaccharide, biology.organism_classification, 01 natural sciences, chemistry.chemical_compound, Diatom, chemistry, Plant cuticle, Geochemistry and Petrology, Botany, Lignin, Carbon, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

The 25 Ma lacustrine deposit of Enspel, Germany, is important for molecular taphonomy as weevils from this site have yielded the oldest preserved traces of chitin. These weevil cuticles show excellent morphological and ultrastructural preservation. Plant cuticle is also preserved but it is obscured or distorted by diatom impressions. Molecular analysis of dicotyledonous angiosperm leaf from the Enspel deposit revealed the presence of polysaccharide, guaiacyl and syringyl related lignin, and possibly degraded protein moieties in the insoluble macromolecular component. Analysis of fossil conifer leaf showed the same moieties, but syringyl related lignin units were absent. Py-GC/MS revealed C 9-33 n-alkyl components from both types of leaf, with C 13,14.29 homologues being the most abundant n-alkanes. TMAH pyrolysis yielded a fatty acid distribution ranging in carbon number from C 6-30, with the C 16,18,14 components being the most abundant. Analysis of fossil weevil cuticle also revealed the presence of an aliphatic polymer as evidenced by C 9-33 n-alkyl components in the pyrolysate and C 6-26 FAMEs (predominantly even-numbered C 14-18 components) in the TMAH pyrolysate. Pyrolysates of the sediments contain alkanes with distributions similar to those observed in the fossils; however, TMAH pyrolysates of sediments were distinct from those of the fossils with C 20-22 components being the most abundant in the conifer-bearing sediment and the even-numbered C 22-26 components dominating in the weevil-bearing sediment. Thus, the aliphatic polymers in the fossils and sediment are different, apparently comprised of moieties of different chain length. This suggests that the aliphatic polymer in the plant and insect fossils is not derived from migration from the organic-rich host sediment.

Published
2007

199. Names for trace fossils: a uniform approach

Author

George R. Demathieu, Michael Schlirf, Jan Kresten Nielsen, Simon J. Braddy, Alfred Uchman, Jorge F. Genise, Andrew K. Rindsberg, Kurt S. S. Nielsen, Richard G. Bromley, Markus Bertling, Radek Mikuláš, Geological and Palaeontological Institute, Westfälische Wilhelms-Universität Münster ( WWU ), School of Earth Sciences [Bristol], University of Bristol [Bristol], Geological Institute, Biogéosciences [Dijon] ( BGS ), AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), CONICET Museo Paleontolögico Egidio Feruglio, Consejo Nacional de Investigaciones Científicas y Técnicas ( CONICET ), Institute of Geology, Czech Academy of Sciences [Prague] ( ASCR ), Exploration and Production, Statoil A.S.A. [Norway], Geological Survey of Alabama, Institute for Palaeontology, Institute of Geological Sciences, Jagiellonian University [Krakow] ( UJ ), Grant (Be 1880/7-1) by the Deutsche Forschungsgemeinschaft, funding from Leverhulme Trust Grant F/82/AZ, from Grant Agency of the Czech Republic for financial support (Grant No. 205/04/0151), from the German Alexander-von-Humboldt-Stiftung, and from Julie von Rüllen Foundation (The Royal Danish Academy of Sciences and Letters)., Westfälische Wilhelms-Universität Münster (WWU), Geological Institute [Copenhagen], University of Copenhagen = Københavns Universitet (KU), Biogéosciences [UMR 6282] [Dijon] (BGS), 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, Museo Paleontológico Egidio Feruglio [Chubut] (MEF), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), Czech Academy of Sciences [Prague] (CAS), University of Alabama [Tuscaloosa] (UA), and Uniwersytet Jagielloński w Krakowie = Jagiellonian University (UJ)

Subjects
Systematics, 010506 paleontology, ichnotaxobases, Ichnotaxa, Biology, Trace fossil, 010502 geochemistry & geophysics, 01 natural sciences, Paleontología, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Sedimentary structures, Paleontology, Ichnology, ichnotaxa, Ichnotaxon, Rusophycus, ichnotaxonomy, Nomenclature, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, [ SDU.STU.PG ] Sciences of the Universe [physics]/Earth Sciences/Paleontology, International Code of Zoological Nomenclature, 15. Life on land, nomenclature, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, CIENCIAS NATURALES Y EXACTAS, trace fossils
Abstract

The taxonomic treatment of trace fossils needs a uniform approach, independent of the ethologic groups concerned. To this aim, trace fossils are rigorously defined with regard to biological taxa and physical sedimentary structures. Potential ichnotaxobases are evaluated, with morphology resulting as the most important criterion. For trace fossils related to bioerosion and herbivory, substrate plays a key role, as well as composition for coprolites. Size, producer, age, facies and preservation are rejected as ichnotaxobases. Separate names for undertracks and other poorly preserved material should gradually be replaced by ichnotaxa based on well-preserved specimens. Recent traces may be identified using established trace fossil taxa but new names can only be based on fossil material, even if the distinction between recent and fossil may frequently remain arbitrary. It is stressed that ichnotaxa must not be incorporated into biological taxa in systematics. Composite trace fossil structures (complex structures made by the combined activity of two or more species) have no ichnotaxonomic standing but compound traces (complex structures made by one individual tracemaker) may be named separately under certain provisions. The following emendations are proposed to the International Code of Zoological Nomenclature: The term ‘work of an animal’ should be deleted from the code, and ichnotaxa should be based solely on trace fossils as defined herein. Fil: Bertling, Markus. University of Münster. Geological and Palaeontological Institute; Alemania Fil: Braddy, Simon J.. University of Bristol. Department of Earth Sciences; Reino Unido Fil: Bromley, Richard G.. Geological Institute Copenhagen; Dinamarca Fil: Demathieu, George R.. University of Burgundy. Earth Sciences Centre; Francia Fil: Genise, Jorge Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina Fil: Mikulás, Radek. Biology Centre of the Academy of Sciences of the Czech Republic; República Checa Fil: Nielsen, Jan K.. Statoil ASA. Exploration and Production; Noruega Fil: Nielsen, Kurt S. S.. Geological Institute Copenhagen; Dinamarca Fil: Rindsberg, Andrew K.. Geological Survey of Alabama; Estados Unidos Fil: Schlirf, Michael. Institute for Palaeontology; Alemania Fil: Uchman, Alfred. Jagiellonian University. Institute of Geological Sciences; Polonia

Published
2006

200. Process-based estimates of terrestrial ecosystem isoprene emissions

Author

Steffen M. Noe, Thomas Hickler, Thomas Karl, S. Pressley, Annett Wolf, Iain Colin Prentice, Dominique Serça, Jaana Bäck, Pertti Hari, Benjamin Smith, Almut Arneth, Ülo Niinemets, Department of Physical Geography and Ecosystems Analysis, Centre for GeoBiosphere Science, Department of Plant Physiology, Institute of Molecular and Cell Biology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences (EMU), University of Washington [Seattle], Forest Ecology and Management [Helsinki], Department of Forest Sciences [Helsinki], Faculty of Agriculture and Forestry [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Faculty of Agriculture and Forestry [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Atmospheric Chemistry Division [Boulder], National Center for Atmospheric Research [Boulder] (NCAR), QUEST [Bristol], School of Earth Sciences [Bristol], University of Bristol [Bristol]-University of Bristol [Bristol], Laboratoire d'aérologie (LAERO), 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), 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), Forest Ecology, University of Helsinki-University of Helsinki-Faculty of Agriculture and Forestry [Helsinki], University of Helsinki-University of Helsinki, 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), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 0106 biological sciences, 010504 meteorology & atmospheric sciences, Flux, Vegetation, 15. Life on land, Atmospheric sciences, 01 natural sciences, Carbon cycle, chemistry.chemical_compound, chemistry, 13. Climate action, Effects of global warming, Atmospheric chemistry, Environmental science, Ecosystem, Terrestrial ecosystem, Isoprene, 010606 plant biology & botany, 0105 earth and related environmental sciences
Abstract

International audience; In recent years evidence has emerged that the amount of isoprene emitted from a leaf is affected by the CO2 growth environment. Many – though not all – laboratory experiments indicate that emissions increase significantly at below-ambient CO2 concentrations and decrease when concentrations are raised to above ambient levels. A small number of process-based leaf isoprene emission models can reproduce this CO2-stimulation and -inhibition. These models are briefly reviewed, and their performance in standard conditions compared with each other and to an empirical algorithm. One of the models was judged particularly useful to be incorporated into a dynamic vegetation model framework, LPJ-GUESS, aiming to develop a tool that allows the interactive effects of climate and increasing CO2 concentration on vegetation distribution, productivity, and leaf and ecosystem isoprene emissions to be explored. The coupled vegetation dynamics-isoprene model is described and used here in a mode particularly suited for the ecosystem scale, but it can be employed at the global level as well. Annual and/or daily isoprene emissions simulated by the model were evaluated against flux measurements (or model estimates that had previously been evaluated with flux data) from a wide range of environments, and agreement between modelled and simulated values was generally good. By using a dynamic vegetation model, effects of canopy composition, disturbance history, or trends in CO2 concentration can be assessed. We show here for five model test sites that the suggested CO2-inhibition of leaf-isoprene metabolism can be large enough to offset increases in emissions due to CO2-stimulation of vegetation productivity and leaf area growth. When effects of climate change are considered atop the effects of atmospheric composition the interactions between the relevant processes will become even more complex. The CO2-isoprene inhibition may have the potential to significantly dampen the expected steep increase of ecosystem isoprene emission in a future warmer atmosphere with higher CO2 levels; this effect raises important questions for projections of future atmospheric chemistry and its connection to the terrestrial vegetation and carbon cycle.

Published
2006

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