Search Results - (Author, Cooperation:J. S. Dunlop)

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  1. 1
    J. S. Dunlop
    American Association for the Advancement of Science (AAAS)
    Published 2011
    Staff View
    Publication Date:
    2011-07-09
    Publisher:
    American Association for the Advancement of Science (AAAS)
    Print ISSN:
    0036-8075
    Electronic ISSN:
    1095-9203
    Topics:
    Biology
    Chemistry and Pharmacology
    Computer Science
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Latest Papers from Table of Contents or Articles in Press
  3. 3
  4. 4
    BUICK, ROGER ; DUNLOP, J. S. R.

    Oxford, UK : Blackwell Publishing Ltd
    Published 1990
    Staff View
    ISSN:
    1365-3091
    Source:
    Blackwell Publishing Journal Backfiles 1879-2005
    Topics:
    Geosciences
    Notes:
    Chemical sediments are common and diverse in the c. 3500 Myr old North Pole chert-barite unit in the Warrawoona Group, Western Australia. Although almost all original minerals were replaced during hydrothermal alteration, metamorphism and deformation, pseudomorphic relics of sedimentary and diagenetic textures and structures show that at least six lithofacies were partly or wholly chemical in origin. These contained five main chemical sedimentary components: primary carbonate mud, diagenetic carbonate crystals, primary sulphate crystals, diagenetic sulphate crystals and diagenetic sulphate nodules. All show a wide range of characteristics consistent only with a marine evaporative origin. Diagenetic carbonate and sulphate crystals, once ferroan dolomite and gypsum, were precipitated within volcanogenic lutites high on littoral mudflats. The other evaporative phases were apparently deposited behind a barrier bar composed of stranded pumice rafts. Primary sulphate crystals, once gypsum and now barite, were precipitated in semi-permanent pools immediately behind the bar. Primary carbonate mud, originally calcitic or aragonitic but now silicified, was deposited in nearby channels and on surrounding mudflats. Within these sediments, diagenetic carbonate crystals (formerly ferroan dolomite) and diagenetic sulphate nodules and crystals (once gypsum) grew during later desiccation. The existence of these evaporites, and more like them in the sediments of other Early Archaean cratons, suggests that shallow marine and terrestrial conditions prevailed over a small but significant portion of the early Earth, contrary to some models of global tectonic evolution. Their overall similarity with more recent evaporitic deposits indicates that there was greater conformity between conditions in modern and primeval sea-shore environments than might be expected, given the great age difference. The attitude implicit in many accounts of Earth's early history, that evaporites were either not deposited or not preserved in Archaean sediments, thus seems to be incorrect.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  5. 5
    DUNLOP, J. S. R. ; MILNE, V. A. ; GROVES, D. I. ; MUIR, M. D.

    [s.l.] : Nature Publishing Group
    Published 1978
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The North Pole barite deposits (11928' E: 2107' S) are contained within the lower units of the Warrawoona Group of the Archaean Pilbara Block of Western Australia1. The deposits occur 160 km SSE of Port Hedland, and 40 km W of Marble Bar. A concordant, bedded chert-barite unit is underlain by ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  6. 6
    LAMBERT, I. B. ; DONNELLY, T. H. ; DUNLOP, J. S. R. ; GROVES, D. I.

    [s.l.] : Nature Publishing Group
    Published 1978
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The North Pole deposits8'9 (2107' S, 11928' E) lie within a 30-m thick fossiliferous10 sequence consisting of laminated chert, silicified arenite and conglomerate, between slightly metamorphosed mafic and ultramafic volcanics of the War-rawoona Group11. Stratigraphie correlations suggest the North ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  7. 7
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The most massive galaxies in the present-day Universe are found to lie in the centres of rich clusters. They have old, coeval stellar populations suggesting that the bulk of their stars must have formed at early epochs in spectacular starbursts, which should be luminous phenomena when observed ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  8. 8
    Dunlop, J. S. ; Downes, A. J. B. ; Peacock, J. A. ; Savage, A. ; Lily, S. J. ; Watson, F. G. ; Longair, M. S.

    [s.l.] : Nature Publishing Group
    Published 1986
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The radio source 1351 -018 lies in one of the deepest areas of the Parkes survey, the six 6.5 x 6.5 Selected Regions, which are complete to flux densities S〉 0.1 Jy at 2.7 GHz (rf. 2). We are carrying out a detailed optical study of the 178 radio sources in the complete sample defined by these ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  9. 9
    Walter, M. R. ; Buick, R. ; Dunlop, J. S. R.

    [s.l.] : Nature Publishing Group
    Published 1980
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] Only in rocks younger than 2,300 Myr, recording the second half of Earth history, is our understanding of the course of biological evolution closely constrained by palaeontological, geochemical and sedimentary evidence5,6. Objects interpreted as microfossils have been reported from 3,300-3,500 Myr ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses