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  • Journal article
    Sephton MA, Botta O, 2005,

    Recognizing life in the solar system: guidance from meteoritic organic matter

    , INT J ASTROBIOL, Vol: 4, Pages: 269-276, ISSN: 1473-5504
  • Conference paper
    Sephton MA, Looy CV, Visscher H, Brinkhuis H, de Leeuw JWet al., 2005,

    The combined petrographic and chemical analysis of end-Permian kerogens

    , 8th International Meeting on Response of the Earth System to Impact Processes (IMPACT), Pages: 467-478

    The end of the Permian was marked by one of the greatest mass extinctions of all time. A valuable record of life and death during this event is contained within sedimentary organic matter. The stable isotopic, molecular and morphological information contained within remains of end-Permian organisms represent an important resource for scientists attempting to produce paleoenvironment reconstructions. Most meaningful data derive from multidisciplinary analyses of the same samples. In these circumstances it is desirable that sample preparation for one approach does not hinder subsequent analysis by another. To ensure compatibility of sample processing procedures the petrographic and chemical consequences of two common kerogen preparation steps, demineralization and screening (sieving), were simultaneously monitored using transmitted light microscopy and flash pyrolysis. Two end-Permian sediments, whose organic content was predominated by land-plant debris, were chosen for this purpose. A limestone was used to assess the problem of fluoride production when dematerializing carbonates and a marl was used to investigate the possibility of introducing a sampling bias following kerogen screening. Flash pyrolysis results of demineralization residues indicate that neoformed fluorides can be effectively removed by repeated treatments with excess concentrated HCl. Flash pyrolysis of screened size fractions (< 10 mu m, 10-18 mu m, 18-30 mu m, 30-125 mu m, 125-250 mu m, > 250 mu m) suggest that, for the end-Permian kerogen used, the various fractions are qualitatively representative of the unscreened kerogen. In a paleoenvironmental context, the homogeneity of the land plant derived kerogen reflects a period of organic accumulation on land followed by rapid deposition and burial in a marine setting. These findings constitute a step forward in the quest for parity between petrographic and chemical analyses of the same kerogen samples.
  • Journal article
    Koeberl C, Farley KA, Peucker-Ehrenbrink B, Sephton MAet al., 2004,

    Geochemistry of the end-Permian extinction event in Austria and Italy: No evidence for an extraterrestrial component

    , GEOLOGY, Vol: 32, Pages: 1053-1056, ISSN: 0091-7613
    • Cite
    • Citations: 70
  • Journal article
    Sephton MA, James RH, Bland PA, 2004,

    Lithium isotope analyses of inorganic constituents from the Murchison meteorite

    , ASTROPHYSICAL JOURNAL, Vol: 612, Pages: 588-591, ISSN: 0004-637X
  • Journal article
    Muxworthy A, Heslop D, Williams W, 2004,

    Influence of magnetostatic interactions on first-order-reversal-curve (FORC) diagrams: a micromagnetic approach

    , GEOPHYSICAL JOURNAL INTERNATIONAL, Vol: 158, Pages: 888-897, ISSN: 0956-540X
    • Cite
    • Citations: 115
  • Journal article
    Visscher H, Looy CV, Collinson ME, Brinkhuis H, Cittert JHAVKV, Kürschner WM, Sephton MAet al., 2004,

    Environmental mutagenesis during the end-Permian ecological crisis

    , PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 101, Pages: 12952-12956, ISSN: 0027-8424
    • Cite
    • Citations: 212
  • Journal article
    Woodland SJ, Rehkämper M, Halliday AN, 2004,

    Further analysis of the Pd-Ag systematics of sulphides from the group IA iron meteorite Canyon diablo

    , Meteoritics and Planetary Science, Vol: 39, ISSN: 1086-9379
  • Conference paper
    Woodland SJ, Rehkämper M, Halliday AN, 2004,

    Further analysis of the Pd-Ag systematics of sulphides from the group Ia iron meteorite Canyon Diablo

    , 67th Annual Meeting of the Meteoritical-Society, Publisher: WILEY, Pages: A114-A114, ISSN: 1086-9379
  • Journal article
    Vermeesch PM, Morgan JV, 2004,

    Chicxulub central crater structure: Initial results from physical property measurements and combined velocity and gravity modeling

    , METEORITICS & PLANETARY SCIENCE, Vol: 39, Pages: 1019-1034, ISSN: 1086-9379
  • Journal article
    Rowe AJ, Wilkinson JJ, Coles BJ, Morgan JVet al., 2004,

    Chicxulub: Testing for post-impact hydrothermal input into the Tertiary ocean

    , METEORITICS & PLANETARY SCIENCE, Vol: 39, Pages: 1223-1231, ISSN: 1086-9379
  • Journal article
    BELL C, MORGAN JV, HAMPSON GJ, TRUDGILL Bet al., 2004,

    Stratigraphic and sedimentological observations from seismic data across the Chicxulub impact basin

    , Meteoritics &amp; Planetary Science, Vol: 39, Pages: 1089-1098, ISSN: 1086-9379

    <jats:p><jats:bold>Abstract</jats:bold>Seismic data across the offshore half of the Chicxulub impact crater reveal a 145 km‐diameter post‐impact basin to be a thickening of Tertiary sediment, which thickens by ˜0.7 sec from the basin margin to the basin center. The basin existed long after the impact and was gradually infilled to its current flat surface. A suite of seismic horizons within the impact basin have been picked on four reflection lines across the crater. They reveal that the western and northwestern parts of the impact basin were filled first. Subsequently, there was a dramatic change in the depositional environment, indicated by an unconformable surface that can be mapped across the entire basin. A prograding shelf sequence downlaps onto this unconformity in the eastern basin. The seismic stratigraphic relationships suggest a marine regression, with sedimentation becoming gradually more passive as sediments fill the eastern part of the impact basin. The central and northeastern parts of the basin are filled last.</jats:p><jats:p>The onshore hole Yaxcopoil‐1 (Yax‐1), which was drilled on the flanks of the southern basin, has been projected onto the offshore seismic data to the west of the crater center. Using dates obtained from this onshore well and regional data, approximate ages have been placed on the most significant horizons in the offshore seismic data. Our preliminary interpretation is that the western and northwestern basins were almost entirely filled by 40 Ma and that the marine regression observed in the eastern basin is early Miocene in age. Offshore seismic stratigraphic analyses and onshore data within Yax‐1 suggest that the early Paleocene is highly attenuated across the impact basin. The Mesozoic section appears to be ˜1 km thicker offshore than onshore. We calculate that, given this offshore thickening, the volume of Mesozoic rocks that have been excavated, melted, or vaporized during impact is
  • Conference paper
    Wichtlhuber S, Rehkämper M, Schiebel R, Halliday ANet al., 2004,

    A new MC-ICPMS method for the determination of Cd/Ca ratios in foraminiferal tests

    , 14th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A486-A486, ISSN: 0016-7037
  • Journal article
    Urrutia-Fucugauchi J, Morgan J, Stöffler D, Claeys Pet al., 2004,

    The Chicxulub Scientific Drilling Project (CSDP)

    , METEORITICS & PLANETARY SCIENCE, Vol: 39, Pages: 787-790, ISSN: 1086-9379
  • Conference paper
    Nielsen SG, Rehkämper M, Halliday AN, 2004,

    First evidence of live <SUP>205</SUP>Pb in the early solar system

    , 14th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A727-A727, ISSN: 0016-7037
  • Conference paper
    Rehkämper M, Nielsen SG, Alt JC, Butterfield DAet al., 2004,

    Using non-traditional stable isotopes as tracers:: What do Tl isotopes tell us about hydrothermal water fluxes?

    , 14th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A365-A365, ISSN: 0016-7037
  • Journal article
    Sephton MA, Bland PA, Pillinger CT, Gilmour Iet al., 2004,

    The preservation state of organic matter in meteorites from Antarctica

    , METEORITICS & PLANETARY SCIENCE, Vol: 39, Pages: 747-754, ISSN: 1086-9379
  • Journal article
    Wombacher F, Rehkämper M, Mezger K, 2004,

    Determination of the mass-dependence of cadmium isotope fractionation during evaporation

    , GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 68, Pages: 2349-2357, ISSN: 0016-7037
  • Journal article
    Sephton MA, 2004,

    Organic matter in ancient meteorites

    , ASTRONOMY & GEOPHYSICS, Vol: 45, Pages: 8-14, ISSN: 1366-8781
  • Journal article
    Nielsen SG, Rehkämper M, Baker J, Halliday ANet al., 2004,

    The precise and accurate determination of thallium isotope compositions and concentrations for water samples by MC-ICPMS

    , CHEMICAL GEOLOGY, Vol: 204, Pages: 109-124, ISSN: 0009-2541
  • Journal article
    Warner M, 2004,

    Free water and seismic reflectivity in the lower continental crust

    , JOURNAL OF GEOPHYSICS AND ENGINEERING, Vol: 1, Pages: 88-101, ISSN: 1742-2132

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