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  • Conference paper
    Muxworthy AR, Taylor S, 2011,

    Evaluation of the domain-state corrected multiple-specimen absolute palaeointensity protocol: a test of historical lavas from Iceland.

    , EGU, Pages: 118-127
  • Journal article
    Cobden LJ, Tong CH, Warner MR, 2011,

    INVERSION OF FULL ACOUSTIC WAVEFIELD IN LOCAL HELIOSEISMOLOGY: A STUDY WITH SYNTHETIC DATA

    , ASTROPHYSICAL JOURNAL, Vol: 727, ISSN: 0004-637X
  • Journal article
    Larner F, Rehkaemper M, Coles BJ, Kreissig K, Weiss DJ, Sampson B, Unsworth C, Strekopytov Set al., 2011,

    A new separation procedure for Cu prior to stable isotope analysis by MC-ICP-MS

    , JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, Vol: 26, Pages: 1627-1632, ISSN: 0267-9477
  • Conference paper
    Muxworthy AR, Heslop D, Williams J, 2011,

    Magnetic dating of major flood events

    , Magnetic Interactions
  • Journal article
    Arnold T, Schönbächler M, Rehkämper M, Dong S, Zhao FJ, Kirk GJ, Coles BJ, Weiss DJet al., 2011,

    Erratum: Measurement of zinc stable isotope ratios in biogeochemical matrices by double-spike MC-ICPMS and determination of the isotope ratio pool available for plants from soil.

    , Anal Bioanal Chem, Vol: 399, ISSN: 1618-2650
  • Conference paper
    Emmerton S, Muxworthy AR, Sephton M, 2011,

    Magnetic characterisation of oil sands and well cores

    , Magnetic Interactions
  • Conference paper
    Muxworthy AR, Harrison R, 2011,

    FORC Workshop – Theory & Practical examples.

    , Magnetic Interactions
  • Journal article
    Williams W, Muxworthy AR, Evans ME, 2011,

    A micromagnetic investigation of magnetite grains in the form of Platonic polyhedra with surface roughness

    , Geochemistry, Geophysics, Geosystems, Vol: 12
  • Conference paper
    Muxworthy AR, 2011,

    Magnetic interactions: Love thy neighbour?

    , BGA Advanced in Geophysics
  • Journal article
    Kamo S, Lana C, Morgan J, 2011,

    U–Pb ages of shocked zircon grains link distal K–Pg boundary sites in Spain and Italy with the Chicxulub impact

    , Earth and Planetary Science Letters, Vol: 310, Pages: 401-408

    The U–Pb ages of shocked zircon crystals from the Chicxulub impact crater and Cretaceous-Paleogene (K-Pg) boundary sites in Haiti, the USA, and Canada, and the pattern of decreasing particle size with paleodistance from the crater, have been used as evidence of a genetic link between Chicxulub and the K–Pg boundary. Despite this, the inference that the K–Pg boundary layer formed as a direct consequence of the Chicxulub impact has been repeatedly questioned. Here we present U–Pb (ID-TIMS) ages and textural evidence of shock metamorphosed zircon grains from the K–Pg boundary at Caravaca, Spain, and Petriccio, Italy, that establish a causal connection between the impact and formation of the K–Pg boundary layer. The shocked zircon grains give data that produce a characteristic age pattern, which indicates a primary source age of 549.5 ± 5.7 Ma and a secondary event at the approximate time of impact at 66 Ma. The intensity of the shock features is proportional to the degree of isotopic resetting, and all textural features and ages are analytically identical to those of previously analyzed zircon from Chicxulub and K–Pg boundary sites in North America. Caravaca and Petriccio were > 8000 km from Chicxulub at the time of impact, and are therefore the farthest K–Pg sites identified that can be linked to Chicxulub through the dating of individual shocked zircon grains. We conclude that the combined age data and textural observations provide unambiguous evidence that ejecta from the Chicxulub impact formed the global K–Pg boundary layer. These data cannot be explained by the alternative scenario that the Chicxulub impact occurred ~ 300 ka prior to the K–Pg boundary.
  • Journal article
    Emmerton S, Muxworthy AR, Hezel DC, Bland PAet al., 2011,

    Magnetic characteristics of CV chondrules with paleointensity implications

    , Journal of Geophysical Research, Vol: in press
  • Journal article
    Muxworthy AR, Heslop D, Paterson GA, Michalk Det al., 2011,

    A Preisach method to estimate absolute paleofield intensity under the constraint of using only isothermal measurements: 2. experimental testing

    , Journal of Geophysical Research, Vol: 116
  • Journal article
    Muxworthy AR, Heslop D, 2011,

    A Preisach method to estimate absolute paleofield intensity under the constraint of using only isothermal measurements: 1. theoretical framework

    , Journal of Geophysical Research, Vol: 116
  • Journal article
    Marlow JJ, Martins Z, Sephton MA, 2011,

    Organic host analogues and the search for life on Mars

    , INT J ASTROBIOL, Vol: 10, Pages: 31-44, ISSN: 1473-5504

    Mars analogue sites represent vital tools in our continued study of the Red Planet; the similar physico-chemical processes that shape a given analogue environment on Earth allow researchers to both prepare for known Martian conditions and uncover presently unknown relationships. This review of organic host analogues – sites on Earth that mimic the putatively low organic content of Mars – examines specific locations that present particular Mars-like obstacles to biological processes. Low temperatures, aridity, high radiation and oxidizing soils characterise modern-day Mars, while acid–saline waters would have presented their own challenges during the planet's warmer and wetter past. By studying each of these hurdles to life on Earth, scientists can prepare instruments headed for Mars and identify the best locations and approaches with which to look for biological signatures. As our use of organic host analogues becomes increasingly sophisticated, researchers will work to identify terrestrial sites exhibiting multiple Mars-like conditions that are tailored to the distinct mineralogical and physical characteristics of Martian locations. Making use of organic host analogues in these ways will enhance the search for signs of past or present life on Mars.
  • Book
    Rothery DA, Gilmour I, Sephton MA, 2011,

    An Introduction to Astrobiology

    , Cambridge, Publisher: Cambridge University Press, ISBN: 9781107600935
  • Book chapter
    Sephton MA, 2011,

    Meteoritics

    , Encyclopedia of Geobiology, Editors: Reitner, Thiel, Publisher: Springer Verlag, Pages: 568-574, ISBN: 9781402092114

    The Encyclopedia of Geobiology is designed as a key reference for students, researchers,teachers, and the informed public to provide basic, but comprehensible ...
  • Journal article
    Krasa D, Muxworthy AR, Williams W, 2011,

    Room- and low-temperature magnetic properties of two-dimensional magnetite particle arrays

    , Geophysical Journal International, Vol: 185, Pages: 167-180
  • Journal article
    Martins Z, Sephton MA, Foing BH, Ehrenfreund Pet al., 2011,

    Extraction of amino acids from soils close to the Mars Desert Research Station (MDRS), Utah

    , International Journal of Astrobiology, Vol: 10, Pages: 231-238
  • Journal article
    Court RW, Sephton MA, 2011,

    The contribution of sulphur dioxide from ablating micrometeorites to the atmospheres of Earth and Mars

    , GEOCHIM COSMOCHIM AC, Vol: 75, Pages: 1704-1717, ISSN: 0016-7037

    Atmospheric composition is a key control on climate and the habitability of planetary surfaces. Ablation of infalling micrometeorites has been recognised as one way in which atmospheric chemistry can be changed, especially at times in solar system history when the infall rates of exogenous material were high. Despite its potential to influence climate and habitability, extraterrestrial sulphur dioxide is currently an unquantified contribution to the atmospheres of the terrestrial planets. We have used flash pyrolysis to simulate the atmospheric entry of micrometeorites and Fourier-transform infrared spectroscopy to identify and quantify the sulphur dioxide produced from the carbonaceous meteorites Orgueil (CI1), ALH 88045 (CM1), Cold Bokkeveld (CM2), Murchison (CM2) and Mokoia (CV3). We have used this approach to understand the introduction of sulphur dioxide to the atmospheres of Earth and Mars from infalling micrometeorites. Sulphates, present in carbonaceous chondrites at a few wt.%, are resistant to thermal decomposition, limiting the yields of sulphur dioxide from unmelted micrometeorites. Infalling micrometeorites are a minor source of present-day sulphur dioxide on Earth and Mars, calculated to be up to around 2400 tonnes and about 350 tonnes, respectively. During the Late Heavy Bombardment (LHB), the much greater infall rates of micrometeoritic dust are calculated to be associated with average production rates of sulphur dioxide of around 20 Mt yr 1 for the early Earth and 0.5 Mt yr 1 for early Mars, for a LHB of 100 Myr. These rates of delivery of sulphur dioxide at high altitudes would have reduced the solar energy reaching the surfaces of these planets, via scattering of sunlight by stratospheric sulphate aerosols, and may have had detrimental effects on developing biospheres by promoting cooler climates and reducing the probability of liquid water on planetary surfaces.
  • Journal article
    Sephton MA, Court RW, Baki AO, Sims MR, Cullen DCet al., 2011,

    New Solvents for Space Missions: Utility for Life Detection Instruments and Notable Terrestrial Applications

    , Recent Patents on Space Technology, Vol: 1, Pages: 7-11, ISSN: 2210-6871

    Instruments designed to test for signs of life on Mars must have operational simplicity and efficiency. One example is the Life Marker Chip being developed to fly on the forthcoming European Space Agency ExoMars mission. Target organic compounds include both polar and non polar molecules and, prior to our patented discovery, no solvent had been tested which effectively extracted both types of molecule in a fashion which was compatible with antibodybased detectors. We have compared the extraction efficiency of water-based solvents alongside conventional organic solvents to determine their suitability for extracting organic mixtures on space missions. Using a range of hydrocarbon standards and a Mars regolith simulant (JSC Mars-1) we have concluded that a water-methanol mix with 1.5 to 2.5 g/L of polysorbate 80 represents the most suitable solvent with extraction efficiencies that can achieve up to approximately 30% of that using conventional organic solvents (assuming 100%efficiency with 93:7 (vol:vol) dichloromethane:methanol mixtures). The surfactant solution will also provide solutions to terrestrial problems, one of which is explored in the patented work.

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