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  • 1
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    PANGAEA
    In:  Supplement to: De Pol-Holz, Ricardo; Keigwin, Lloyd D; Southon, John R; Hebbeln, Dierk; Mohtadi, Mahyar (2010): No signature of abyssal carbon in intermediate waters off Chile during deglaciaition. Nature Geoscience, 3(3), 192-195, https://doi.org/10.1038/ngeo745
    Publication Date: 2023-06-27
    Description: At the end of the Last Glacial Maximum (19,000 to 11,000 years ago), atmospheric carbon dioxide concentrations rose while the Delta14C of atmospheric carbon dioxide declined**1, 2. These changes have been attributed to an injection of carbon dioxide with low radiocarbon activity from an oceanic abyssal reservoir that was isolated from the atmosphere for several thousand years before deglaciation**3. The current understanding points to the Southern Ocean as the main area of exchange between these reservoirs4. Intermediate water formed in the Southern Ocean surrounding Antarctica would have then carried the old carbon dioxide signature to the lower-latitude oceans**5, 6. Here we reconstruct the Delta14C signature of Antarctic Intermediate Water off the coast of Chile for the past 20,000 years, using paired 14C ages of benthic and planktonic foraminifera. In contrast to the above scenario, we find that the delta14C signature of the Antarctic Intermediate Water closely matches the modelled surface ocean Delta14C, precluding the influence of an old carbon source. We suggest that if the abyssal ocean is indeed the source of the radiocarbon-depleted carbon dioxide, an alternative path for the mixing and propagation of its carbon dioxide may be required to explain the observed changes in atmospheric carbon dioxide concentration and radiocarbon activity.
    Keywords: Age, 14C AMS; Age, dated; Age, dated standard deviation; Calendar age; Calendar age, standard deviation; Center for Marine Environmental Sciences; DEPTH, sediment/rock; Gravity corer (Kiel type); MARUM; Sample code/label; SL; SO161/5; SO161/5_22SL; Sonne; SPOC; Taxon/taxa; Δ14C
    Type: Dataset
    Format: text/tab-separated-values, 209 data points
    Location Call Number Expected Availability
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  • 2
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    Unknown
    PANGAEA
    In:  Supplement to: Magana, Alexandra L; Southon, John R; Kennett, James P; Roark, E Brendan; Sarnthein, Michael; Stott, Lowell D (2010): Resolving the cause of large differences between deglacial benthic foraminifera radiocarbon measurements in Santa Barbara Basin. Paleoceanography, 115(4), PA4102, https://doi.org/10.1029/2010PA002011
    Publication Date: 2024-01-09
    Description: To better understand the deglacial upwelling pattern in the east Pacific, we have made radiocarbon (14C) measurements on benthic foraminifera and macrofauna from a 3.5 m long interval in ODP Core 893A from Santa Barbara Basin, California, representing early deglaciation. This work serves to investigate the source of apparent disagreement between radiocarbon data sets from Leibnitz Laboratory, Kiel University (Kiel) and Carbon Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory (LLNL). These data sets are based on measurements of mixed benthic and mixed planktonic foraminifera. Interlaboratory 14C results are similar for the planktonic foraminiferal analyses; however, Kiel measurements on mixed benthic foraminifera are much older than mixed benthic measurements from equivalent depths measured at LLNL. Our new results show distinct 14C differences between taxa, with Pyrgo sp. giving ages consistently older than Kiel measurements on mixed benthic taxa, while ages for Nonionellina sp., Buliminella sp., Uvigerina sp., and benthic macrofauna were much younger, even younger than the LLNL mixed benthic data. The new data supports benthic-planktonic age offsets of no more than 300 years, indicating that bottom waters within the basin remained significantly younger during early deglaciation than some previous results have suggested and are thus consistent with sedimentary and faunal evidence for well-oxygenated conditions.
    Keywords: 146-893A; Age, 14C AMS; Age, dated; Age, dated material; Age, dated standard deviation; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Foraminifera, benthic δ13C; Joides Resolution; Laboratory; Leg146; North Pacific Ocean; Ocean Drilling Program; ODP; Sample code/label
    Type: Dataset
    Format: text/tab-separated-values, 600 data points
    Location Call Number Expected Availability
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