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  • 1
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    (Table S1) Radiocarbon data of sediment core SO161/5 22SL (2010)
    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
    Details
    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
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    DATA PANGAEA
  • 2
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    (Table 1) Age determination of ODP Hole 146-893A (2010)
    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
    Details
    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
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    DATA PANGAEA
  • 3
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    Blank assessment for ultra-small radiocarbon samples : chemical extraction and separation versus AMS (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2010. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 52 (2010): 1322-1335.
    Description: The Keck Carbon Cycle AMS facility at the University of California, Irvine (KCCAMS/UCI) has developed protocols for analyzing radiocarbon in samples as small as ~0.001 mg of carbon (C). Mass-balance background corrections for modern and 14C-dead carbon contamination (MC and DC, respectively) can be assessed by measuring 14C-free and modern standards, respectively, using the same sample processing techniques that are applied to unknown samples. This approach can be validated by measuring secondary standards of similar size and 14C composition to the unknown samples. Ordinary sample processing (such as ABA or leaching pretreatment, combustion/graphitization, and handling) introduces MC contamination of ~0.6 ± 0.3 μg C, while DC is ~0.3 ± 0.15 μg C. Today, the laboratory routinely analyzes graphite samples as small as 0.015 mg C for external submissions and ≅0.001 mg C for internal research activities with a precision of ~1% for ~0.010 mg C. However, when analyzing ultra-small samples isolated by a series of complex chemical and chromatographic methods (such as individual compounds), integrated procedural blanks may be far larger and more variable than those associated with combustion/graphitization alone. In some instances, the mass ratio of these blanks to the compounds of interest may be so high that the reported 14C results are meaningless. Thus, the abundance and variability of both MC and DC contamination encountered during ultra-small sample analysis must be carefully and thoroughly evaluated. Four case studies are presented to illustrate how extraction chemistry blanks are determined.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 4
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    Marine04 marine radiocarbon age calibration, 0-26 cal kyr BP (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2004. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 46 (2004): 1059-1086.
    Description: New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision, and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically-dated tree-ring samples, converted with a box diffusion model to marine mixed-layer ages, cover the period from 0–10.5 cal kyr BP. Beyond 10.5 cal kyr BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific 14C reservoir age information to provide a single global marine mixed-layer calibration from 10.5–26.0 cal kyr BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the 14C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring data sets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al. (this issue).
    Description: A portion of this work was performed under National Science Foundation grant ATM-0407554. A portion of this work was performed under the auspices of the U S Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
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    NotCal04; comparison/ calibration 14C records 26-50 cal kyr BP (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2004. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 46 (2004): 1225-1238.
    Description: The radiocarbon calibration curve IntCal04 extends back to 26 cal kyr BP. While several high-resolution records exist beyond this limit, these data sets exhibit discrepancies of up to several millennia. As a result, no calibration curve for the time range 26–50 cal kyr BP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 6
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    A preliminary determination of the absolute 14C/12C ratio of OX-I (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2007. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 49 (2007): 441-445.
    Description: A preliminary determination of the absolute 14C/12C ratio of the oxalic acid I standard (NBS SRM 4990B) has been made. Using an accelerator mass spectrometry (AMS) system, a known number of radiocarbon ions were implanted in a thin copper foil. The foil was then combusted with the addition of 14C-free carrier material. This resulting gas (which had a known 14C/12C ratio) was graphitized and compared to OX-I material. This comparison yielded an absolute 14C/12C ratio of OX-I. The absolute 14C/12C ratio of OX-I, coupled with knowledge of the specific activity of OX-1, provides an alternative determination of the 14C half-life.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 7
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    Low reservoir ages for the surface ocean from mid-Holocene Florida corals (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 23 (2008): PA2209, doi:10.1029/2007PA001527.
    Description: The 14C reservoir age of the surface ocean was determined for two Holocene periods (4908–4955 and 3008–3066 calendar (cal) B.P.) using U/Th-dated corals from Biscayne National Park, Florida, United States. We found that the average reservoir ages for these two time periods (294 ± 33 and 291 ± 27 years, respectively) were lower than the average value between A.D. 1600 and 1900 (390 ± 60 years) from corals. It appears that the surface ocean was closer to isotopic equilibrium with CO2 in the atmosphere during these two time periods than it was during recent times. Seasonal δ 18O measurements from the younger coral are similar to modern values, suggesting that mixing with open ocean waters was indeed occurring during this coral's lifetime. Likely explanations for the lower reservoir age include increased stratification of the surface ocean or increased Δ14C values of subsurface waters that mix into the surface. Our results imply that a more correct reservoir age correction for radiocarbon measurements of marine samples in this location from the time periods ∼3040 and ∼4930 cal years B.P. is ∼292 ± 30 years, less than the canonical value of 404 ± 20 years.
    Description: NSF Chemical Oceanography program provided monetary support under grants OCE-9711326, OCE-0137207, and OCE-0551940 (to ERMD).
    Keywords: Reservoir age ; Radiocarbon ; Corals
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
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    The Keck Carbon Cycle AMS Laboratory, University of California, Irvine : status report (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors. This work is licensed under a Creative Commons Attribution 3.0 License The definitive version was published in Radiocarbon 52 (2010): 301-309.
    Description: We present a status report of the accelerator mass spectrometry (AMS) facility at the University of California, Irvine, USA. Recent spectrometer upgrades and repairs are discussed. Modifications to preparation laboratory procedures designed to improve sample throughput efficiency while maintaining precision of 2–3‰ for 1-mg samples (Santos et al. 2007c) are presented.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 9
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    Cariaco Basin calibration update; revisions to calendar and 14C chronologies for core PL07-58PC (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2004. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 46 (2004): 1161-1187.
    Description: This paper describes the methods used to develop the Cariaco Basin PL07-58PC marine radiocarbon calibration data set. Background measurements are provided for the period when Cariaco samples were run, as well as revisions leading to the most recent version of the floating varve chronology. The floating Cariaco chronology has been anchored to an updated and expanded Preboreal pine tree-ring data set, with better estimates of uncertainty in the wiggle-match. Pending any further changes to the dendrochronology, these results represent the final Cariaco 58PC calibration data set.
    Description: This work was supported by LLNL (97-ERI-009), DOE (W-7405-Eng-48), and NSF (ATM- 9709563).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 10
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    IntCal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP (2011)
    Dept. of Geosciences, University of Arizona
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Arizona Board of Regents on behalf of the University of Arizona, 2009. This article is posted here by permission of Dept. of Geosciences, University of Arizona for personal use, not for redistribution. The definitive version was published in Radiocarbon 51 (2009): 1111-1150.
    Description: The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available in the Supplemental Material at www.radiocarbon.org.
    Description: We would like to acknowledge support for this project from the UK Natural Environment Research Council NE/E018807/1 and IGBP PAGES (Past Global Changes).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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