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  • Journal article
    Pearson VK, Kearsley AT, Sephton MA, Gilmour Iet al., 2007,

    The labelling of meteoritic organic material using osmium tetroxide vapour impregnation

    , PLANET SPACE SCI, Vol: 55, Pages: 1310-1318, ISSN: 0032-0633
  • Book chapter
    Muxworthy A R, Roberts A P, 2007,

    First-order reversal curve (FORC) diagrams

    , Encyclopedia of Geomagnetism and Paleomagnetism, Editors: Gubbins, Herrero-Bervera, Publisher: Springer, Pages: 266-272, ISBN: 9781402044236
  • Journal article
    Wignall PB, Zonneveld J-P, Newton RJ, Amor K, Sephton MA, Hartley Set al., 2007,

    The end Triassic mass extinction record of Williston Lake, British Columbia

    , PALAEOGEOGR PALAEOCL, Vol: 253, Pages: 385-406, ISSN: 0031-0182
  • Journal article
    Court RW, Sephton MA, Parnell J, Gilmour Iet al., 2007,

    Raman spectroscopy of irradiated organic matter

    , GEOCHIM COSMOCHIM AC, Vol: 71, Pages: 2547-2568, ISSN: 0016-7037

    Raman spectroscopy of a range of irradiated and nonirradiated natural terrestrial bitumens has revealed that radiolytic alteration is generally associated with an increase in structural disorganisation. An interpretational methodology designed to overcome the considerable difficulties in obtaining reproducible, meaningful parameters of structural disorganisation is also presented, and should prove useful for future Raman applications. Raman investigation of a set of bitumens reported to have formed by the radiolytic polymerisation of light hydrocarbons, such as methane, has revealed excessive structural disorganisation, relative to biogenic complex-hydrocarbon-derived bitumens of similar radioelement concentrations, which may indicate the importance of precursor materials on the organic products of irradiation. Variations in the R1 ratio (D1/G band intensity) are found to be the best guide to variations in structural organisation. Comparisons of Raman spectra of the same sample, but produced by different exciting wavelengths, reveal the importance of the selection of a suitable laser wavelength. The results are discussed in terms of analyses of irradiated organic matter in the solar system, especially cometary nuclei and carbonaceous chondrites.
  • Journal article
    Ripperger S, Rehkaemper M, 2007,

    A highly sensitive MC-ICPMS method for Cd/Ca analyses of foraminiferal tests

    , JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, Vol: 22, Pages: 1275-1283, ISSN: 0267-9477
  • Journal article
    Parbhakar A, Cuadros J, Sephton MA, Dubbin W, Coles BJ, Weiss Det al., 2007,

    Adsorption of L-lysine on montmorillonite

    , COLLOID SURFACE A, Vol: 307, Pages: 142-149, ISSN: 0927-7757

    Amino acid adsorption on smectite is relevant to prebiotic processes involving possible catalytic reactions in the early Solar System, as implied by the clay-organic correlation found in meteorites, and the generation and modification of organic components essential for the origin of life. Here we report the results of a study investigating the adsorption of l-lysine (0.025–0.4 M) onto montmorillonite. The reaction products were studied using X-ray diffraction, chemical analysis and infrared spectroscopy.We find that lysine adsorption is first dominated by cation exchange and then by adsorption of electrically neutral lysine (as a zwitterion), as indicated by chemical and FTIR evidence. At the maximum concentration, lysine displaces only ∼1/3 of the original interlayer cations. The d-spacing of the smectite–lysine complex increases from 1.2 to 2.1 nm as more lysine enters the interlayer space, and water is expelled. We propose a structural model of lysine sorption in the interlayer in which lysine is oriented at >45–90◦ to the plane of siloxane O atoms.
  • Journal article
    Siegert MJ, Behar A, Bentley M, Blake D, Bowden S, Christoffersen P, Cockell C, Corr H, Cullen DC, Edwards H, Ellery A, Ellis-Evans C, Griffiths G, Hindmarsh R, Hodgson DA, King E, Lamb H, Lane L, Makinson K, Mowlem M, Parnell J, Pearce DA, Priscu J, Rivera A, Sephton MA, Sims MR, Smith AM, Tranter M, Wadham JL, Wilson G, Woodward Jet al., 2007,

    Exploration of Ellsworth Subglacial Lake: a concept paper on the development, organisation and execution of an experiment to explore, measure and sample the environment of a West Antarctic subglacial lake

    , Reviews in Environmental Science and Biotechnology, Vol: 6, Pages: 161-179, ISSN: 1569-1705
  • Journal article
    Parnell J, Cullen D, Sims MR, Bowden S, Cockell CS, Court R, Ehrenfreund P, Gaubert F, Grant W, Parro V, Rohmer M, Sephton M, Stan-Lotter H, Steele A, Toporski J, Vago Jet al., 2007,

    Searching for Life on Mars: Selection of Molecular Targets for ESA’s Aurora ExoMars Mission

    , Astrobiology, Vol: 7, Pages: 578-604, ISSN: 1531-1074

    The European Space Agency’s ExoMars mission will seek evidence of organic compounds of biological and non-biological origin at the martian surface. One of the instruments in the Pasteur payload may be a Life Marker Chip that utilizes an immunoassay approach to detect specific organic molecules or classes of molecules. Therefore, it is necessary to define and prioritize specific molecular targets for antibody development. Target compounds have been selected to represent meteoritic input, fossil organic matter, extant (living, recently dead) organic matter, and contamination. Once organic molecules are detected on Mars, further information is likely to derive from the detailed distribution of compounds rather than from single molecular identification. This will include concentration gradients beneath the surface and gradients from generic to specific compounds. The choice of biomarkers is informed by terrestrial biology but is wide ranging, and nonterrestrial biology may be evident from unexpected molecular distributions. One of the most important requirements is to sample where irradiation and oxidation are minimized, either by drilling or by using naturally excavated exposures. Analyzing regolith samples will allow for the search of both extant and fossil biomarkers, but sequential extraction would be required to optimize the analysis of each of these in turn.
  • Journal article
    Perry RS, Sephton MA, 2007,

    Baking black opal in the desert sun: The importance of silica in desert varnish: comment and reply

    , GEOLOGY, Vol: 35, Pages: e123-e123, ISSN: 0091-7613
  • Journal article
    Perry RS, Mcloughlin N, Lynne BY, Sephton MA, Oliver JD, Perry CC, Campbell K, Engel MH, Farmer JD, Brasier MD, Staley JTet al., 2007,

    Defining biominerals and organominerals: Direct and indirect indicators of life

    , SED GEOL, Vol: 201, Pages: 157-179, ISSN: 0037-0738
  • Journal article
    Zolensky ME, Zega TJ, Yano H, Wirick S, Westphal AJ, Weisberg MK, Weber I, Warren JL, Velbel MA, Tsuchiyama A, Tsou P, Toppani A, Tomioka N, Tomeoka K, Teslich N, Taheri M, Susini J, Stroud R, Stephan T, Stadermann FJ, Snead CJ, Simon SB, Simionovici A, See TH, Robert F, Rietmeijer FJM, Rao W, Perronnet MC, Papanastassiou DA, Okudaira K, Ohsumi K, Ohnishi I, Nakamura-Messenger K, Nakamura T, Mostefaoui S, Mikouchi T, Meibom A, Matrajt G, Marcus MA, Leroux H, Lemelle L, Le L, Lanzirotti A, Langenhorst F, Krot AN, Keller LP, Kearsley AT, Joswiak D, Jacob D, Ishii H, Harvey R, Hagiya K, Grossman L, Grossman JN, Graham GA, Gounelle M, Gillet P, Genge MJ, Flynn G, Ferroir T, Fallon S, Ebel DS, Dai ZR, Cordier P, Clark B, Chi M, Butterworth AL, Brownlee DE, Bridges JC, Brennan S, Brearley A, Bradley JP, Bleuet P, Bland PA, Bastien Ret al., 2006,

    Report - Mineralogy and petrology of comet 81P/Wild 2 nucleus samples

    , SCIENCE, Vol: 314, Pages: 1735-1739, ISSN: 0036-8075
  • Journal article
    Brownlee D, Tsou P, Aleon J, Alexander CMO, Araki T, Bajt S, Baratta GA, Bastien R, Bland P, Bleuet P, Borg J, Bradley JP, Brearley A, Brenker F, Brennan S, Bridges JC, Browning ND, Brucato JR, Bullock E, Burchell MJ, Busemann H, Butterworth A, Chaussidon M, Cheuvront A, Chi M, Cintala MJ, Clark BC, Clemett SJ, Cody G, Colangeli L, Cooper G, Cordier P, Daghlian C, Dai Z, D'Hendecourt L, Djouadi Z, Dominguez G, Duxbury T, Dworkin JP, Ebel DS, Economou TE, Fakra S, Fairey SAJ, Fallon S, Ferrini G, Ferroir T, Fleckenstein H, Floss C, Flynn G, Franchi IA, Fries M, Gainsforth Z, Gallien J-P, Genge M, Gilles MK, Gillet P, Gilmour J, Glavin DP, Gounelle M, Grady MM, Graham GA, Grant PG, Green SF, Grossemy F, Grossman L, Grossman JN, Guan Y, Hagiya K, Harvey R, Heck P, Herzog GF, Hoppe P, Hoerz F, Huth J, Hutcheon ID, Ignatyev K, Ishii H, Ito M, Jacob D, Jacobsen C, Jacobsen S, Jones S, Joswiak D, Jurewicz A, Kearsley AT, Keller LP, Khodja H, Kilcoyne ALD, Kissel J, Krot A, Langenhorst F, Lanzirotti A, Le L, Leshin LA, Leitner J, Lemelle L, Leroux H, Liu M-C, Luening K, Lyon I, MacPherson G, Marcus MA, Marhas K, Marty B, Matrajt G, McKeegan K, Meibom A, Mennella V, Messenger K, Messenger S, Mikouchi T, Mostefaoui S, Nakamura T, Nakano T, Newville M, Nittler LR, Ohnishi I, Ohsumi K, Okudaira K, Papanastassiou DA, Palma R, Palumbo ME, Pepin RO, Perkins D, Perronnet M, Pianetta P, Rao W, Rietmeijer FJM, Robert F, Rost D, Rotundi A, Ryan R, Sandford SA, Schwandt CS, See TH, Schlutter D, Sheffield-Parker J, Simionovici A, Simon S, Sitnitsky I, Snead CJ, Spencer MK, Stadermann FJ, Steele A, Stephan T, Stroud R, Susini J, Sutton SR, Suzuki Y, Taheri M, Taylor S, Teslich N, Tomeoka K, Tomioka N, Toppani A, Trigo-Rodriguez JM, Troadec D, Tsuchiyama A, Tuzzolino AJ, Tyliszczak T, Uesugi K, Velbel M, Vellenga J, Vicenzi E, Vincze L, Warren J, Weber I, Weisberg M, Westphal AJ, Wirick S, Wooden D, Wopenka B, Wozniakiewicz P, Wright I, Yabuta H, Yano H, Young ED, Zare RN, Zega T, Ziegleret al., 2006,

    Comet 81P/Wild 2 under a microscope

    , SCIENCE, Vol: 314, Pages: 1711-1716, ISSN: 0036-8075
  • Journal article
    Goldin TJ, Wunnemann K, Melosh HJ, Collins GSet al., 2006,

    Hydrocode modeling of the Sierra Madera impact structure

    , METEORIT PLANET SCI, Vol: 41, Pages: 1947-1958, ISSN: 1086-9379
  • Journal article
    Muxworthy AR, Williams W, 2006,

    Critical single-domain/multidomain grain sizes in noninteracting and interacting elongated magnetite particles: Implications for magnetosomes

    , JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 111, ISSN: 2169-9313
  • Journal article
    Williams W, Muxworthy AR, Paterson GA, 2006,

    Configurational anisotropy in single-domain and pseudosingle-domain grains of magnetite

    , JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 111, ISSN: 2169-9313
  • 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 Y, Morgan JV, 2006,

    Crosshole seismic waveform tomography - II. Resolution analysis

    , GEOPHYSICAL JOURNAL INTERNATIONAL, Vol: 166, Pages: 1237-1248, ISSN: 0956-540X
  • 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

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