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  • GEOMAR Katalog / E-Books  (2)
  • OceanRep  (3)
Publikationsart
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  • 1
    Schlagwort(e): Bericht ; Forschungsbericht
    Materialart: Buch
    Seiten: 217 S , graph. Darst., Kt
    ISBN: 2910180123
    Serie: Les rapports des campagnes à la mer à bord du Marion-Dufresne 96,1
    Sprache: Französisch
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Schlagwort(e): Hochschulschrift
    Materialart: Buch
    Seiten: 216 S.
    Sprache: Französisch
    Anmerkung: Marseille, Univ. Aix-Marseille III, these, 1993
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2021-02-08
    Beschreibung: Accurate reconstruction of past ocean temperatures is of critical importance to paleoclimatology. Carbonate clumped isotope thermometry ("L'l47") is a relatively recent technique based on the strong relationship between calcification temperature and the statistical excess of 13C- 180 bonds in carbonates. Its application to foraminifera holds great scientific potential, particularly because Ll47 paleotemperature reconstructions do not require assumptions regarding the 180 composition of seawater. However there are still relatively few published observations investigating the potential influence of parameters such as salinity or foraminiferal size and species. We present a new calibration data set based on 234 replicate analyses of9 planktonic and 2 benthic species of foraminifera collected from recent core-top sediments, with calcification temperatures ranging from -2 to 25 °C. We observe a strong relationship between Ll47 values and independent, oxygen-IS estimates of calcification temperatures: L'l47 = 41.63 x 103 /T2 + 0.2056 The formal precision of this regression(± 0.7-1.0 °C at 95 % confidence level) is much smaller than typical analytical errors. Our observations confirm the absence of significant species-specific biases or salinity effects. We also investigate potential foraminifer size effects between 200 and 〉560 μm in 6 species, and conclude that all size fractions from a given core-top location and species display statistically undistinguishable L'l47 values. These findings provide a robust foundation for future interlaboratories comparisons and paleoceanographic applications.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Publikationsdatum: 2023-02-08
    Beschreibung: We performed a downcore comparison of Mg/Ca ratios obtained using reductive and non-reductive cleaning methods applied to Globigerinoides ruber, Pulleniatina obliquiloculata and Globorotalia menardii picked along two nearby sediment cores retrieved at 2100 m and 3875 m in the eastern equatorial Indian Ocean. At the shallower site, our results show statistically significant discrepancies in averaged relative Mg/Ca loss induced by the reductive cleaning compared to non-reductive cleaning: G. menardii (8.5%) 〉 G. ruber (6.2%) 〉 P. obliquiloculata (4.4%), suggesting that reductive cleaning impact on relative Mg/Ca loss is species-specific. At the deeper site, differences between the relative Mg/Ca losses for the three species are smaller: G. menardii (3.7%), G. ruber (4.1%) and P. obliquiloculata (6.3%), suggesting the clear impact of in situ preservation state on the cleaning related Mg/Ca loss. The Mg/Ca loss in both relative (%) and absolute (mmol/mol) value of species G. ruber and G. menardii are significantly smaller at the deeper site than the shallower site, implying that these two species which have experienced intense dissolution on the sea-floor are less prone to lose further Mg during the reductive cleaning. P. obliquiloculata, however, show non-significant difference in Mg/Ca loss between the two sites, indicating that the cleaning related Mg/Ca loss in this species is somewhat insensitive to the preservation state at our two sites. Our data reveal that Mg/Ca loss results from partial dissolution induced by the reductive step. We conclude that the non-reductive cleaning approach should be preferred for building inter-laboratory homogeneous datasets of Mg/Ca-derived temperatures, whereas the reductive step should be only included when severe oxide coating is observed.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Publikationsdatum: 2024-02-07
    Beschreibung: Planktonic Foraminifera are unique paleo-environmental indicators through their excellent fossil record in ocean sediments. Their distribution and diversity are affected by different environmental factors including anthropogenically forced ocean and climate change. Until now, historical changes in their distribution have not been fully assessed at the global scale. Here we present the FORCIS (Foraminifera Response to Climatic Stress) database on foraminiferal species diversity and distribution in the global ocean from 1910 until 2018 including published and unpublished data. The FORCIS database includes data collected using plankton tows, continuous plankton recorder, sediment traps and plankton pump, and contains similar to 22,000, similar to 157,000, similar to 9,000, similar to 400 subsamples, respectively (one single plankton aliquot collected within a depth range, time interval, size fraction range, at a single location) from each category. Our database provides a perspective of the distribution patterns of planktonic Foraminifera in the global ocean on large spatial (regional to basin scale, and at the vertical scale), and temporal (seasonal to interdecadal) scales over the past century.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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