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  • 1
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    Geological Society
    In:  In: Marine petroleum source rocks. , ed. by Brooks, J. Geological Society London Special Publications, 26 . Geological Society, London, pp. 181-197.
    Publication Date: 2016-02-26
    Description: he present-day upwelling circulation off Peru, the regional pattern of organic matter in surface sediments and the stable carbon isotope characteristics of Neogene and Quaternary carbonate lithologies suggest a unique feedback mechanism in continental margin deposition and subsequent alteration after burial. In such a scenario, the high bioproductivity, the position of a poleward flowing undercurrent and the rate of subsidence of margin basins appear to be the principal variables controlling this mechanism. Transfer of organic matter from the sea surface to the sea floor is particularly efficient in the upwelling ecosystem off Peru. Preservation and burial are enhanced by high bulk sedimentation rates along the upper continental slope (between 11°–15°S) at depths where the subsurface current velocities decrease below those normally associated with the poleward flow. Burial and preservation are diminished, however, where shallow water depths promote continuous reworking of the bottom sediments by onshore flows and alongshore water movement (between 6°–10°S). The resulting sedimentary facies are distinctly different from each other in that the former process yields an organic-rich (〉 5 wt % Corg) and the latter process yields a calcareous (〉 15 wt % CaCo3) mud facies. The bulk sediment accumulation and individual component fluxes are estimated for both portions of the margin situated between 6° and 15°S latitude and lying in 〈 500 m of water depth. Furthermore, the chemical environment of organic-matter decomposition in the rapidly accumulating carbonate-poor facies is dominated by microbial fermentation and methanogenesis, whereas, the muds containing lesser amounts of organic matter are dominated by microbial sulphate reduction. These differences in facies composition persist throughout the subsequent stages of compaction and diagenesis. Most prominent among these is the formation of ‘organic’ dolomites with distinctly different isotopic signatures and mineral assemblages. The original upwelling facies (i.e., organic-rich muds or calcareous muds), the extent of reworking by subsurface currents, and the subsidence history of the margin basins may be inferred from these sedimentary signatures.
    Type: Book chapter , PeerReviewed
    Format: text
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 269 (1977), S. 661-663 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Berger–Heath model of vertical mixing in deep-sea sediments provides a simple means of simulating an original input signal by ‘unmixing’ a signal found in deep-sea cores. When applied to an oxygen isotope record from the western equatorial Pacific, the possibility emerges that ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 303 (1983), S. 231-233 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We analysed five box cores (PLDS 66, 68, 70, 72 and 74) all from water depths near 4,000 m close to the Equator, and from between 100 W and 115W; Core PLDS 72 may be taken as typical. Carbonate percentages, physical properties, and diatom stratigraphy have already been published for this core5'7. ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 60 (1980), S. 129-135 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isotopic ratios 18O/16O and 13C/12C show an annal periodicity in the strombid snails Strombus gigas and S. costatus from Bermuda. S. gigas appears to have a constant displacement of 0.5‰ from oxygen isotopic equilibrium, whereas S. costatus fractionates the oxygen istopes in accordance with established fractionation relationships. With this tool, the growth in strombid snails during different stage can readily be determined on one and the same snail. A 24.8 cm long S. gigas showed an age of 7, a 19.3 cm long S. costatus of 5, and a 7.8 cm long S. costatus of 2 years. From the annual range in oxygen isotopes, growth restricted to warmer periods of the year is assumed. The abundances of 18O and 13C tend to be positively correlated in adult S. gigas and S. costatus speciments, but were inversely related in a juvenile S. costatus.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 64 (1977), S. 634-635 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 314 (1985), S. 156-158 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Two-step deglaciation has been proposed previously, notably by Duplessy et al6 who based their conclusions both on extensive micropalaeontological work at the Institut de Geologic du Bassin d'Aquitaine, and on new radiocarbon-dated 618O signals measured at Gif-sur-Yvette. Berger7 proposed that the ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 303 (1983), S. 231-233 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We analysed five box cores (PLDS 66, 68, 70, 72 and 74) all from water depths near 4,000 m close to the Equator, and from between 100 W and 115W; Core PLDS 72 may be taken as typical. Carbonate percentages, physical properties, and diatom stratigraphy have already been published for this core5'7. ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 287 (1980), S. 218-221 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The spreading centre here opens at a rate of ocmyr 1, intermediate in the spectrum of spreading rates3'4. The rise crest consists of an uplifted axial zone 5-km wide and 80-m high5. The zone of most recent volcanism is between 600 and 1,400m wide6, and the hydrothermal vents occur within a strip ...
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 289 (1981), S. 639-643 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] When ranked according to deviation from isotopic equilibrium, deep-sea benthic foraminifera exhibit no correlation between the rankings for oxygen and for carbon. Both rank sequences are stable from east to west in the equatorial Pacific (fertility-independent) and from Glacial to post-Glacial ...
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