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Conference paperMuxworthy AR, Williams W, 2005,
Low-temperature cooling behavior of single-domain magnetite: forcing of the crystallographic axes and interactions (invited)
, AGU Fall -
Conference paperSephton MA, Looy CV, Visscher H, et 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: 467-478The 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.
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Conference paperPerry RS, Kolb VM, Philip A I, et al., 2005,
Making silica rock coatings in the lab: synthetic desert varnish (art. no. 59060U)
, Conference on Astrobiology and Planetary Missions, Publisher: The International Society for Optical Engineering, Pages: 1-11 -
Conference paperWilliams W, Muxworthy AR, Paterson G, 2005,
Configurational anisotropy in equidimensional grains (poster)
, AGU Fall -
Journal articleKoeberl C, Farley KA, Peucker-Ehrenbrink B, et 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- Author Web Link
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- Citations: 64
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Journal articleSephton 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- Author Web Link
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- Citations: 14
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Journal articleMuxworthy 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- Author Web Link
- Open Access Link
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- Citations: 105
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Journal articleVisscher H, Looy CV, Collinson ME, et 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- Author Web Link
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- Citations: 194
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Journal articleWoodland 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 -
Journal articleBELL C, MORGAN JV, HAMPSON GJ, et al., 2004,
Stratigraphic and sedimentological observations from seismic data across the Chicxulub impact basin
, Meteoritics & 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
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Journal articleRowe AJ, Wilkinson JJ, Coles BJ, et al., 2004,
Chicxulub: Testing for post-impact hydrothermal input into the Tertiary ocean
, METEORITICS & PLANETARY SCIENCE, Vol: 39, Pages: 1223-1231, ISSN: 1086-9379- Author Web Link
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- Citations: 15
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Journal articleWombacher 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- Author Web Link
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- Citations: 100
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Journal articleSephton MA, Bland PA, Pillinger CT, et al., 2004,
The preservation state of organic matter in meteorites from Antarctica
, METEORITICS & PLANETARY SCIENCE, Vol: 39, Pages: 747-754, ISSN: 1086-9379- Author Web Link
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- Citations: 30
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Journal articleSephton MA, 2004,
Organic matter in ancient meteorites
, ASTRONOMY & GEOPHYSICS, Vol: 45, Pages: 8-14, ISSN: 1366-8781- Author Web Link
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- Citations: 21
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Journal articleNielsen SG, Rehkämper M, Baker J, et 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- Author Web Link
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- Citations: 100
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Journal articleWarner 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- Author Web Link
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- Citations: 14
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Journal articleRehkämper M, Nielsen SG, 2004,
The mass balance of dissolved thallium in the oceans
, MARINE CHEMISTRY, Vol: 85, Pages: 125-139, ISSN: 0304-4203- Author Web Link
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- Citations: 90
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Journal articleSephton MA, Love GD, Watson JS, et al., 2004,
Hydropyrolysis of insoluble carbonaceous matter in the Murchison meteorite: New insights into its macromolecular structure
, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 68, Pages: 1385-1393, ISSN: 0016-7037- Author Web Link
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- Citations: 103
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Journal articleFehr MA, Rehkämper M, Halliday AN, 2004,
Application of MC-ICPMS to the precise determination of tellurium isotope compositions in chondrites, iron meteorites and sulfides
, INTERNATIONAL JOURNAL OF MASS SPECTROMETRY, Vol: 232, Pages: 83-94, ISSN: 1387-3806- Author Web Link
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- Citations: 70
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Journal articleRehkämper M, Frank M, Hein JR, et al., 2004,
Cenozoic marine geochemistry of thallium deduced from isotopic studies of ferromanganese crusts and pelagic sediments
, EARTH AND PLANETARY SCIENCE LETTERS, Vol: 219, Pages: 77-91, ISSN: 0012-821X- Author Web Link
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- Citations: 96
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