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  • Journal article
    Nielsen SG, Rehkamper M, Teagle DAH, Butterfield DA, Alt JC, Halliday ANet al., 2006,

    Hydrothermal fluid fluxes calculated from the isotopic mass balance of thallium in the ocean crust

    , EARTH AND PLANETARY SCIENCE LETTERS, Vol: 251, Pages: 120-133, ISSN: 0012-821X
  • Journal article
    Morgan J V, Lana C, Kearsley A, Coles B, Belcher C, Montanari S, Diaz-Martinez E, Barbosa A, Neumann Vet al., 2006,

    Analyses of shocked quartz at the global K-P boundary indicate an origin from a single, high-angle, oblique impact at Chicxulub

    , Earth and Planetary Science Letters, Vol: 251, Pages: 264-279, ISSN: 0012-821X
  • Journal article
    Carvallo C, Muxworthy A, 2006,

    Low-temperature first-order reversal curve (FORC) diagrams for synthetic and natural samples

    , GEOCHEM GEOPHY GEOSY, Vol: 7, ISSN: 1525-2027

    [ 1] First-order reversal curve (FORC) diagrams were measured on a variety of synthetic and natural ( submarine basalts and potsherds) samples, as well as for a mixture, between room temperature and 10 K. Measuring FORC diagrams allowed us to examine the behavior of the coercivity field and interaction field distributions with decreasing temperature. Generally, as the temperature is decreased, FORC contours were observed to expand in all directions, e. g., the maximum coercivity peak migrates toward a higher coercivity. For synthetic magnetite samples, there were abrupt changes in the FORC distribution at the Verwey transition ( 120 K), while in the more complex natural magnetite samples the FORC distribution gradually progressed with temperature. As the temperature decreased, FORC diagrams were found to display different domain state characteristics. For example, samples with dominant superparamagnetic signals became single-domain (SD)-like, a SD-like sample stayed SD-like, and a PSD-like sample became more SD-like. In addition to these general features, we also observed some more specialized features. First, in both synthetic and natural magnetite samples, a secondary higher-coercivity peak is occasionally present below the Verwey transition, which we suggest is a twinning contribution. Second, the coercivity increases by a factor 15 between 300 K and 20 K in some of the seamount samples. Third, the effect of field cooling/ zero-field cooling on FORC diagrams is negligible, with the hysteresis parameters HC and HCR displaying a greater dependency. Finally, it is shown that in mixtures of magnetite and hematite, the hematite contribution disappears on cooling below the Morin transition, leaving a strong, well-defined magnetite signal.
  • Journal article
    Rao Y, Wang YH, Morgan JV, 2006,

    Crosshole seismic waveform tomography - II. Resolution analysis

    , Geophysical Journal International, Vol: 166, Pages: 1237-1248, ISSN: 1365-246X

    In an accompanying paper, we used waveform tomography to obtain a velocity model between two boreholes from a real crosshole seismic experiment. As for all inversions of geophysical data, it is important to make an assessment of the final model, to determine which parts of the model are well-resolved and can confidently be used for geological interpretation. In this paper we use checkerboard tests to provide a quantitative estimate of the performance of the inversion and the reliability of the final velocity model. We use the output from the checkerboard tests to determine resolvability across the velocity model. Such tests can act as good guides for designing appropriate inversion strategies. Here we discovered that, by including both reference-model and smoothing constraints in initial inversions, and then relaxing the smoothing constraint for later inversions, an optimum velocity image was obtained. Additionally, we noticed that the performance of the inversion was dependent on a relationship between velocity perturbation and checkerboard grid-size: larger velocity perturbations were better-resolved when the grid-size was also increased. Our results suggest that model assessment is an essential step prior to interpreting features in waveform tomographic images.
  • Journal article
    Pearson VK, Sephton MA, Gilmour I, 2006,

    Molecular and isotopic indicators of alteration in CR chondrites

    , METEORITICS & PLANETARY SCIENCE, Vol: 41, Pages: 1291-1303, ISSN: 1086-9379
  • Conference paper
    Ripperger S, Rehkaemper M, Halliday AN, 2006,

    Cadmium isotope fractionation in seawater

    , 16th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A535-A535, ISSN: 0016-7037
  • Conference paper
    Rehkamper M, Nielsen SG, Teagle DAH, Alt JC, Butterfield DAet al., 2006,

    Thallium isotope constraints on the water fluxes of ridge flank hydrothermal systems

    , 16th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A524-A524, ISSN: 0016-7037
  • Conference paper
    Zolensky M, Bland P, Bradley J, Brearley A, Brennan S, Bridges J, Brownlee D, Buttervorth A, Dai Z, Ebel D, Genge M, Gounelle M, Graham G, Grossman J, Grossman L, Harvey R, Ishii H, Kearsley A, Keller L, Krot A, Langenhorst F, Lanzirotti A, Leroux H, Matrajt G, Messenger K, Mikouchi T, Nakamura T, Ohsumi K, Okudaira K, Perronnet M, Rietmeijer F, Simon S, Stephan T, Stroud R, Taheri M, Tomeoka K, Toppani A, Tsou P, Tsuchiyama A, Velbel M, Weber I, Weisberg M, Westphal A, Yano H, Zega Tet al., 2006,

    Mineralogy and petrology of Comet Wild-2 nucleus samples - Final results of the preliminary examination team

    , 69th Annual Meeting of the Meteoritical Society, Publisher: METEORITICAL SOC, Pages: A167-A167, ISSN: 1086-9379
  • Conference paper
    Nielsen SG, Wood BJ, Rehkaemper M, Halliday ANet al., 2006,

    An experimental study of thallium partitioning and isotope fractionation during planetary core formation processes

    , 69th Annual Meeting of the Meteoritical Society, Publisher: METEORITICAL SOC, Pages: A131-A131, ISSN: 1086-9379
  • Conference paper
    Preston LJ, Genge MJ, Ghail R, 2006,

    Microbial structures in hydrothermal deposits as biomarkers for Mars

    , 69th Annual Meeting of the Meteoritical Society, Publisher: METEORITICAL SOC, Pages: A143-A143, ISSN: 1086-9379
  • Conference paper
    Genge MJ, 2006,

    Equilibrated ordinary chondrite-like micrometeorites

    , 69th Annual Meeting of the Meteoritical-Society, Publisher: WILEY, Pages: A62-A62, ISSN: 1086-9379
  • Conference paper
    Bland PA, Jackson MD, Coker RF, Cohen BA, Benedix GKet al., 2006,

    Why asteroidal alteration was isochemical: High porosity not equal high permeability

    , 69th Annual Meeting of the Meteoritical Society, Pages: A22-A22, ISSN: 1086-9379
  • Conference paper
    Rehkaemper M, Nielsen SG, Williams HM, Schoenbachler M, Halliday ANet al., 2006,

    Radiogenic and stable thallium isotope variations in iron meteorites

    , 69th Annual Meeting of the Meteoritical Society, Publisher: METEORITICAL SOC, Pages: A147-A147, ISSN: 1086-9379
  • Journal article
    Perry RS, Sephton MA, 2006,

    Desert varnish: an environmental recorder for Mars

    , ASTRONOMY & GEOPHYSICS, Vol: 47, Pages: 34-35, ISSN: 1366-8781
  • Journal article
    Muxworthy AR, Williams W, 2006,

    Low-temperature cooling behavior of single-domain magnetite: Forcing of the crystallographic axes and interactions

    , JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 111, ISSN: 2169-9313
  • Journal article
    Fehr MA, Rehkaemper M, Halliday AN, Schoenbaechler M, Hattendorf B, Guenther Det al., 2006,

    Search for nucleosynthetic and radiogenic tellurium isotope anomalies in carbonaceous chondrites

    , GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 70, Pages: 3436-3448, ISSN: 0016-7037
  • Journal article
    Sephton MA, James RH, Zolensky ME, 2006,

    The origin of dark inclusions in Allende: New evidence from lithium isotopes

    , METEORITICS & PLANETARY SCIENCE, Vol: 41, Pages: 1039-1043, ISSN: 1086-9379
  • Journal article
    Chironi C, Morgan JV, Warner MR, 2006,

    Imaging of intrabasalt and subbasalt structure with full wavefield seismic tomography

    , JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 111, ISSN: 2169-9313
  • Journal article
    Nielsen SG, Rehkämper M, Halliday AN, 2006,

    Large thallium isotopic variations in iron meteorites and evidence for lead-205 in the early solar system

    , GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 70, Pages: 2643-2657, ISSN: 0016-7037
  • Journal article
    Genge MJ, 2006,

    Igneous rims on micrometeorites

    , GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 70, Pages: 2603-2621, ISSN: 0016-7037

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