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Cited by 78Archaeology and ancient environmental studiesGeology and Paleoclimatology ResearchTree-ring climate responses

Reanalysis of the Atmospheric Radiocarbon Calibration Record from Lake Suigetsu, Japan

Open access
Bronk Ramsey, Christopher, Heaton, Timothy J, Schlolaut, Gordon, Staff, Richard A, Bryant, Charlotte L, Brauer, Achim, Lamb, Henry F, Marshall, Michael H +1 more·2020·Radiocarbon
DOI 10.1017/rdc.2020.18
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Abstract

ABSTRACT Terrestrial plant macrofossils from the sedimentary record of Lake Suigetsu, Japan, provide the only quasi-continuous direct atmospheric record of radiocarbon (14C) covering the last 50 ka cal BP (Bronk Ramsey et al. 2012). Since then, new high precision data have become available on U-Th dated speleothems from Hulu Cave China, covering the same time range (Cheng et al. 2018). In addition, an updated varve-based chronology has also been published for the 2006 core from Lake Suigetsu (SG06) based on extended microscopic analysis of the sediments and improved algorithms for interpolation (Schlolaut et al. 2018). Here we reanalyze the radiocarbon dataset from Suigetsu based on the new varve counting information and the constraints imposed by the speleothem data. This enables the new information on the calendar age scale of the Suigetsu dataset to be used in the construction of the consensus IntCal calibration curve. Comparison of the speleothem and plant macrofossil records provides insight into the mechanisms underlying the incorporation of carbon into different types of record and the relative strengths of different types of archive for calibration purposes.

AI snapshot

Written from the paper’s full text.

TL;DR

This paper reworks the Lake Suigetsu plant macrofossil radiocarbon record using a revised varve chronology and Hulu Cave speleothem constraints, then incorporates it into IntCal20. It finds close overall agreement but identifies two intervals where varve-based sedimentation rates may be too high, and suggests Suigetsu preserves more high-frequency atmospheric ¹⁴C variation than Hulu.

Key findings

  • The reanalysis used 639 radiocarbon dates from the SG93 and SG06 cores, corresponding to 593 distinct depths over 1397.4–4040.75 cm; one date, SUERC-28223, was excluded because its error was large and it was reported as >42,700 BP.
  • The updated SG06 2018 varve chronology extended the record by roughly 10 ka to 4041 cm composite depth; above that boundary, about half of years on average lacked countable seasonal layers and were interpolated with the Varve Interpolation Program.
  • Offsets between Suigetsu and reservoir-corrected Hulu data were negligible: 21±19 yr for k=0.1, 12±17 yr for k=0.2, 5±16 yr for k=0.3, 8±19 yr with 100 yr extra error, and -1±32 yr with 200 yr extra error.
  • Two intervals could not be supported by the varve uncertainty range: about 1730–1820 cm composite depth (~15–18 kvyr BP) with an age difference of ~300 years, and about 2700–2880 cm (~29.3–32.6 kvyr BP) with ~700 years; Suigetsu splines also showed more high-frequency signal than Hulu, and deconvolution of Hulu with a 420-year linear ramp accentuated features seen in Suigetsu.

Methods

  • Data: 639 Lake Suigetsu ¹⁴C dates from the SG93 and SG06 cores, with 593 distinct depths, plus the Hulu Cave record of ~500 ¹⁴C determinations from three speleothems spanning 10.6–54 ka cal BP.
  • Analysis: an OxCal Poisson-process P_Sequence model was run against the Hulu timescale with k=0.2, with sensitivity tests at k=0.1 and k=0.3 and additional relative uncertainties of 100 and 200 years; a Hulu-only curve was built using an errors-in-variables Bayesian spline with 400 knots, 250,000 MCMC iterations, half discarded as burn-in, and dead carbon fraction allowed to vary by ±50 years.
  • Integration: marginal posterior calendar ages and a correlation matrix for Suigetsu depths were used as priors in the IntCal20 curve construction.

Limitations

  • Stated in the paper: varve chronologies carry significant cumulative uncertainty; macrofossil availability can be limiting; μXRF counts were excluded because thin varves may be underrepresented in low-sedimentation intervals, though the affected locations are uncertain; the two offset intervals lack independent proof and their explanation remains theoretical; Suigetsu’s high-frequency signal could be noise or real; and Hulu’s dead carbon or reservoir effect is uncertain.
  • Evident from the text: the final IntCal20 curve mutes some of Suigetsu’s high-frequency structure, and testing those signals depends on other records such as Cariaco and floating tree-ring sequences; the correlated calendar-age uncertainty across Suigetsu levels also complicates interpretation.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1017/rdc.2020.18

Cites

16 of 16 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

5 of 33 cited sources checked · 3 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    The revised Suigetsu dataset is part of the IntCal20 calibration curve.

    “The revised Suigetsu dataset is included within the IntCal20 calibration curve, as described by Heaton et al. (2020 in this issue).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Heaton et al. 2020 source
  • Premisecitation

    The Suigetsu record contains many substantial terrestrial plant macrofossils that three laboratories have radiocarbon dated.

    “Furthermore, the record contains large numbers of substantial terrestrial plant macrofossils, radiocarbon dated by three different laboratories (Kitagawa and van der Plicht 1998;Bronk Ramsey et al. 2012).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites Kitagawa and van der Plicht 1998 source

      The paper reports more than 250 terrestrial macrofossils from Lake Suigetsu sediments that were radiocarbon dated (p. 2). It says those measurements were made at the Groningen AMS facility; it does not support the claim that three different laboratories dated them. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites Bronk Ramsey et al. 2012 source
    • Rests on an assumption: The plant macrofossils sampled from Lake Suigetsu are from non-aquatic species and therefore record atmospheric 14C.
  • Interpretationcitation

    Much available marine data, including U-Th dated corals, share the offset pattern seen here, despite scatter from diagenesis.

    “However, it is clear that much of the available marine data, including the U-Th dated corals, share the pattern seen here, even though there is some scatter due to diagenesis.This is evident in the placement of the IntCal09 (Reimer et al. 2009) curve relative to IntCal13.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Reimer et al. 2009 source

      The Introduction and IntCal09 Curve Construction sections say that IntCal09 incorporates marine records, including independently dated corals, and the Data Set Selection Criteria section discusses screening corals for diagenesis. The paper presents the IntCal09 curve, but it does not compare its placement with IntCal13 or establish that the marine data share the citing paper’s observed pattern. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Findingown data

    Many dates in the preliminary model had significantly low agreement indices.

    “In practice there were many dates with significantly low agreement indices, so we also tested the impact of increasing the relative uncertainty in the radiocarbon dates between the Hulu and Suigetsu datasets by both 100 and 200 years.”
    Quote in the paperSubstantial claim
  • Findingown data

    The method yields a correlation coefficient matrix for all distinct levels.

    “Secondly, a correlation coefficient matrix for all distinct levels has been generated; given the nature of the underlying varve chronology there is a considerable degree of correlation between closely spaced dates (implying that calendar age shifts to one require others nearby to be similarly shifted).”
    Quote in the paperSubstantial claim
  • May combine two claims. 21
  • Classified as probably not a substantial claim. 9

  • May combine two claims.

    Findingcitation

    In the younger sequence down to about 28 kvyr BP, offsets from the varve chronology were expected and resemble those for IntCal13.

    “In the younger part of the sequence (down to about 28 kvyr BP in the varve chronology) the offsets were expected and are similar to those seen for IntCal13 (Reimer et al. 2013).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Reimer et al. 2013 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The Hulu-only atmospheric 14C estimate was produced with the same errors-in-variables Bayesian spline method used for the main IntCal20 curve.

    “We created a Hulu-cave-only (Hulu-Cal) estimate of atmospheric 14 C using the same errors-in-variables Bayesian spline approach taken to create the main IntCal20 curve (see Heaton et al. 2020 in this issue).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Heaton et al. 2020 source
    • The authors state this as an assumption: The uncertainties on the U-Th based calendar ages for each Hulu 14C determination are independent of one another.

  • May combine two claims.

    Findingown data

    All offset estimates are within error limits and consistent with no systematic offset between the Suigetsu and Hulu datasets.

    “However, all are, within error limits, consistent with a zero systematic offset.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The uncertainties on the U-Th based calendar ages for each Hulu 14C determination are independent of one another.

  • May combine two claims.

    Findingown data

    The 2012 and 2018 varve chronologies agree very well for most of the record, except between 1980 and 2375 cm composite depth.

    “Despite these major changes, the 2012 and 2018 varve chronologies are in very good agreement for most of the record, with a notable exception between 1980 and 2375 cm composite depth.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The Suigetsu dataset's main distinguishing features are that it requires no dead carbon or reservoir effect and that its calendar age uncertainty is correlated.

    “The main distinguishing features of this dataset are: i) that there is no dead carbon or reservoir effect required, and ii) the correlated nature of the calendar age uncertainty.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the 1980-2375 cm interval, the 2018 chronology implies a higher sedimentation rate and younger ages than the 2012 chronology, although the 2012 chronology remains within the 2018 error estimate.

    “In this interval the 2018 varve chronology suggests a higher sedimentation rate, i.e. younger ages, though the 2012 chronology is still within the error estimate of the 2018 chronology.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Adding 100 or 200 years of relative uncertainty to the Hulu and Suigetsu radiocarbon dates changed model outputs slightly, especially below 15 kvyr BP, but all changes stayed within the model's 95% error limits.

    “Although this did produce slightly different model outputs (particularly in the region <15 kvyr BP of the varve chronology), these were all well within the 95% error limits of the model (see Figure 2), so it was decided to use the unmodified data without any additional errors.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The models found a consistently negligible offset between the Suigetsu and reservoir-corrected Hulu datasets: 21±19 for k=0.1, 12±17 for k=0.2, 5±16 for k=0.3, 8±19 for k=0.2 with extra error 100, and -1±32 for k=0.2 with extra error 200.

    “The models all showed a consistently negligible offset between the datasets: 21±19 for k=0.1, 12±17 for k=0.2, 5±16 for k=0.3, 8±19 for k=0.2 with an extra error of 100, and -1±32 for k=0.2 with an extra error of 200.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The uncertainties on the U-Th based calendar ages for each Hulu 14C determination are independent of one another.

  • Classified as probably not a substantial claim. May combine two claims.

    Findingown data

    At the Laschamp excursion (~41k cal BP), Suigetsu uncertainties become large, so the 20-35k cal BP period with smaller measurement uncertainty is more useful.

    “At the Laschamp excursion (circa 41k cal BP) the uncertainties become large in the Suigetsu data, and so it is more useful to focus on the period where the measurement uncertainty is smaller (20-35k cal BP; see Figure 5).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    In both intervals, final age-scale sedimentation rates are lower than the smallest rates within the varve model's uncertainty range, leaving age differences of ~300 years in the upper interval and ~700 years in the lower interval.

    “In either case the sedimentation rates of the final age-scale are lower than the smallest sedimentation rates within the uncertainty range of the varve model, so that an age difference remains: in the upper interval ~300 years and in the lower interval ~700 years.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Between 30 and 40 kvyr BP, the new Hulu data constrain offsets much better and shift SG06 significantly older, revealing both apparent under-counting and over-counting in the varve chronology.

    “However, for the period between 30 and 40 kvyr BP the offsets are much better constrained by the new Hulu data.This shifts the SG06 data significantly older in this period with sections of both apparent under-counting and over-counting seen in the varve chronology.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The final age model lies slightly farther from the varve-only model and quite close to the preliminary Hulu-based model that would have been obtained with lower model rigidity.

    “In general the final age model is pulled slightly further away from the varve-only model and is quite close to the preliminary model (against Hulu) that we would have obtained with a lower model rigidity (see Figure 1 above).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The 2018 varve chronology extends about 10 ka beyond the 2012 chronology, reaching a composite depth of 4041 cm.

    “Compared to the 2012 varve chronology (SG06 2012 vyr BP chronology; Bronk Ramsey et al. 2012;Marshall et al. 2012) the 2018 iteration has been extended by approximately 10 ka to a composite depth of 4041 cm (correlation model ver.28 Feb. 2019).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Schlolaut et al. 2018 source
    • cites Bronk Ramsey et al. 2012 source
    • cites Marshall et al. 2012 source

  • May combine two claims.

    Interpretationreasoning

    The marginal posterior dates for each Suigetsu SG06 level use all other calibration-curve data and give the best age estimate for SG06 sediments.

    “These estimates make use of all of the other data included within the calibration curve, and so provide our best estimate of the age of the sediments within SG06.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Except for the last case, SG06 dates were slightly older than corrected Hulu data, suggesting the Hulu reservoir or dead carbon fraction may be marginally overestimated.

    “In all cases but the last, the SG06 dates were slightly older when compared to the corrected Hulu data suggesting, if anything, the Hulu reservoir (or dead carbon fraction) to be marginally over estimated.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The uncertainties on the U-Th based calendar ages for each Hulu 14C determination are independent of one another.

  • May combine two claims.

    Premisecitation

    The Lake Suigetsu sediment record is unusual because it spans the full radiocarbon technique range and contains varves throughout the interval lacking dendrochronological calibration data.

    “More specifically, we look particularly at the lacustrine sediment record of Lake Suigetsu, central Japan (Nakagawa et al. 2012) which is unusual in covering the full range of the radiocarbon technique, with varves (albeit of variable quality) throughout the period for which we have no dendrochronogically based calibration datasets.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Nakagawa et al. 2012 source

  • May combine two claims.

    Premisecitation

    The Hulu Cave speleothem records have an unusually low dead carbon fraction or reservoir effect and cover the same pre-Holocene range.

    “We also choose to focus on the unique series of speleothem records from Hulu Cave, China (Southon et al. 2012;Cheng et al. 2018) characterized by an unusually low dead carbon fraction or reservoir effect, and with coverage over the same range of the pre-Holocene period.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Southon et al. 2012 source
    • cites Cheng et al. 2018 source

  • May combine two claims.

    Interpretationreasoning

    Properly modelling and including calendar age covariance in curve construction improves noise-signal separation and preserves more of the Suigetsu record's structure in IntCal20.

    “Correctly modelling and including this calendar age covariance, also present within the Cariaco, Pakistan, and Iberian margin chronologies, into curve construction is important.It improves our ability to distinguish what is noise and what is signal by making it easier to identify common features when combining the full set of varied records; and means that more of the structure and shape of the Su”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The Hulu Cave 14C record comprises three speleothems: H82, MSD, and MSL.

    “The Hulu cave 14 C record from Tang Shan, near Nanjing in Eastern China, consists of three speleothems (H82, Southon et al. 2012;MSD and MSL, Cheng et al. 2018).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Southon et al. 2012 source
    • cites Cheng et al. 2018 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The preliminary model's sensitivity to the P_Sequence rigidity parameter k was tested at k=0.1 and k=0.3.

    “However, the sensitivity of the model to different choices of this parameter was investigated (at k=0.1, which is less rigid, and k=0.3, which is more rigid).”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    The 2018 Suigetsu varve chronology counts seasonal layers using thin-section microscopy.

    “The 2018 Suigetsu varve chronology (SG06 2018 vyr BP chronology; Schlolaut et al. 2018) is based on the counts of seasonal layers using thin section microscopy.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Schlolaut et al. 2018 source

  • May combine two claims.

    Interpretationown data

    Deconvolution of the Hulu data accentuates some features seen in the Suigetsu data, suggesting the Suigetsu signals are at least not entirely noise.

    “this is to retain as much of the authentic higher in Figure 6 where you can see that this does actually accentuate some features seen in the Suigetsu data, suggesting that the signals seen in Suigetsu are at least not entirely noise.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The age-model offset might result from environmental conditions specific to microfacies zone II.a2 affecting varve formation.

    “Since a microfacies zone indicates specific environmental conditions different from those of other microfacies zones, this offset in the age model might indeed be due to the effect of these environmental conditions on varve formation.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationcitation

    If low sediment accumulation conditions also hindered varve formation, thin varves would be underrepresented, causing too high an interpolated sedimentation rate.

    “This means that if environmental conditions which lead to low sediment accumulation were also unfavourable for varve formation, then thin varves are underrepresented.This in turn would lead to a problem in the interpolation (Schlolaut et al. 2018) resulting in too high an interpolated sedimentation rate.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Schlolaut et al. 2018 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The atmospheric offset seen in Hulu may be more a reservoir effect than a dead carbon fraction.

    “The implication of this is that the offset from the atmosphere seen in Hulu may be more of a reservoir effect than a dead carbon fraction.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Microfacies zone II.a2 has few seasonal layers, and a very high proportion of those layers are of low quality and poorly distinguishable.

    “This interval is characterized by a low frequency of seasonal layers, with a very high proportion of the occurring layers being of low quality, i.e. poorly distinguishable.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Schlolaut et al. 2018 source

  • May combine two claims.

    Interpretationreasoning

    The Suigetsu dataset is direct, atmospheric, and unfiltered, and is closest in nature to the terrestrial samples many radiocarbon users date.

    “In particular, it provides a direct atmospheric and unfiltered dataset, which is closest in nature to the types of terrestrial samples many users of radiocarbon will be using for chronological purposes.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    If the offsets stem from a varve-model error, systematic under-representation of small varve thicknesses could explain them because the varve model is interpolated.

    “If these offsets are indeed due to an error in the varve model, then there are only a limited number of potential reasons for that.Since the varve model is interpolated, a systematic under-representation of, in this case, small varve thicknesses could be a reason.”
    Quote in the paperNot a substantial claim
28 of 28

  • The paper relies on this without support.

    There is no near-term prospect that dendrochronology will cover the full range of the radiocarbon dating technique.

    “There is, however, no immediate prospect for this to cover the full range of the radiocarbon dating technique and so we must therefore fall back on other types of record for the older section of the curve, all of which have their strengths and limitations.”

  • The paper relies on this without support.

    Varve chronologies carry significant cumulative uncertainties.

    “Their disadvantages are that the varve chronologies have significant cumulative uncertainties, and finding enough substantial plant macrofossils can be a challenge.”

  • The paper relies on this without support.

    The plant macrofossils sampled from Lake Suigetsu are from non-aquatic species and therefore record atmospheric 14C.

    “these have the advantage of being atmospheric (since the plant species sampled are not aquatic)”

  • The paper relies on this without support.

    Thin varves may be systematically underrepresented in intervals with low sedimentation rate in the μXRF count because of a methodological limit.

    “The main reason for this exclusion was that, due to a methodological limit, thin varves may be systematically underrepresented in intervals with a low sedimentation rate in the μXRF count.”

  • The authors state this as an assumption.

    The uncertainties on the U-Th based calendar ages for each Hulu 14C determination are independent of one another.

    “The uncertainties on the U-Th based calendar ages for each 14 C determination were considered independent from one another.”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • An updated timescale for Lake Suigetsu was modeled using both the new varve chronology and a 14C wiggle-match to the extended Hulu Cave record.

    “An updated timescale was modeled (Bronk Ramsey et al. 2020 in this issue) using both the new varve chronology and a 14 C wiggle-match to the extended Hulu Cave record (Cheng et al. 2018).”

    From The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP) (2020) · cites this paper as Bronk Ramsey et al. 2020 in this issue

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Related

Authors
Bronk Ramsey, C., Heaton, T. J., Schlolaut, G., Staff, R. A., Bryant, C. L., Brauer, A., Lamb, H. F., Marshall, M. H., & Nakagawa, T.
Affiliations
  • University of Sheffield (GB)
  • Japan Agency for Marine-Earth Science and Technology (JP)
  • Scottish Universities Environmental Research Centre (GB)
  • GFZ Helmholtz Centre for Geosciences (DE)
  • Aberystwyth University (GB)
  • Ritsumeikan University (JP)
ORCID
Venue
Radiocarbon
Publisher
Cambridge University Press (CUP)
Published
2020-03-25
Volume
62
Issue
4
Pages
989-999
ISSN
  • 0033-8222 (ISSN-L)
  • 1945-5755
DOI
10.1017/rdc.2020.18
OpenAlex
W2994961501
Cited by
77
References
17
Citations by year
2026: 2 · 2025: 9 · 2024: 3 · 2023: 13 · 2022: 19 · 2021: 23 · 2020: 8
FWCI
9.02
Type
journal article
Language
en
Open access
Licence
www.cambridge.org/core/terms (unspecified)
Locations
  • Radiocarbon (publishedVersion)
  • ENLIGHTEN (Jurnal Bimbingan dan Konseling Islam) (acceptedVersion, cc-by-sa)
  • White Rose Research Online (University of Leeds, The University of Sheffield, University of York) (submittedVersion)
  • Publication Database GFZ (GFZ German Research Centre for Geosciences) (submittedVersion)
Funders
  • Natural Environment Research Council (NE/F004400/1, NE/H007865/1, NE/D011604/1, NRCF010002, NE/F003056/1, NE/S011854/1, NE/D012996/1)
  • Japan Society for the Promotion of Science (15H06905)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Archaeology and ancient environmental studies
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Geology and Paleoclimatology Research
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Tree-ring climate responses
Keywords
atmospheric radiocarbon, radiocarbon calibration, Lake Suigetsu, varve chronology, Hulu Cave, paleoclimate archives

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