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  • 1
    Electronic Resource
    Electronic Resource
    Old radiocarbon ages in the southwest Pacific Ocean during the last glacial period and deglaciation (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 405 (2000), S. 555-559 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Marine radiocarbon (14C) dates are widely used for dating oceanic events and as tracers of ocean circulation, essential components for understanding ocean–climate interactions. Past ocean ventilation rates have been determined by the difference between radiocarbon ages of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35014581
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    Paper (German National Licenses)
    Fulltext
  • 2
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    THE INTCAL20 NORTHERN HEMISPHERE RADIOCARBON AGE CALIBRATION CURVE (0–55 CAL kBP) (2020)
    Department of Geosciences, University of Arizona | Cambridge University Press
    In:  Radiocarbon, 62 (4). pp. 725-757.
    Details
    Publication Date: 2021-01-08
    Description: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
    DOI: 10.1017/RDC.2020.41
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Late Quaternary palaeoenvironment of northern Guatemala: evidence from deep drill cores and seismic stratigraphy of Lake Petén Itzá (2010)
    Wiley-Blackwell - STM ; International Association of Sedimentologists
    In:  Sedimentology, 57 (5). pp. 1220-1245.
    Details
    Publication Date: 2019-01-24
    Description: Long sediment cores were collected in spring 2006 from Lake Petén Itzá, northern Guatemala, in water depths ranging from 30 to 150 m, as part of an International Continental Scientific Drilling Program project. The sediment records from deep water consist mainly of alternating clay, gypsum and carbonate units and, in at least two drill sites, extend back 〉200 kyr. Most of the lithostratigraphic units are traceable throughout the basin along seismic reflections that serve as seismic stratigraphic boundaries and suggest that the lithostratigraphy can be used to infer regional palaeoenvironmental changes. A revised seismic stratigraphy was established on the basis of integrated lithological and seismic reflection data from the basin. From ca 200 to ca 85 ka, sediments are dominated by carbonate-clay silt, often interbedded with sandy turbidites, indicating a sediment regime dominated by detrital sedimentation in a relatively humid climate. At ca 85 ka, an exposure horizon consisting of gravels, coarse sand and terrestrial gastropods marks a lake lowstand or partial basin desiccation, indicating dry climate conditions. From ca 85 to ca 48 ka, transgressive carbonate-clay sediments, overlain by deep-water clays, suggest a lake level rise and subsequent stabilization at high stage. From ca 48 ka to present, the lithology is characterized by alternating clay and gypsum units. Gypsum deposition correlates with Heinrich Events (i.e. dry climate), whereas clay units coincide with more humid interstadials.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/j.1365-3091.2009.01144.x
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Upper-ocean-to-atmosphere radiocarbon offsets imply fast deglacial carbon dioxide release (2010)
    Nature Publishing Group
    In:  Nature, 466 (7310). pp. 1093-1097.
    Details
    Publication Date: 2015-09-07
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1038/nature09288
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    An 85-ka record of climate change in lowland Central America (2008)
    Elsevier
    In:  Quaternary Science Reviews, 27 . pp. 1152-1165.
    Details
    Publication Date: 2019-09-23
    Description: Drill cores obtained from Lake Petén Itzá, Petén, Guatemala, contain a ∼85-kyr record of terrestrial climate from lowland Central America that was used to reconstruct hydrologic changes in the northern Neotropics during the last glaciation. Sediments are composed of alternating clay and gypsum reflecting relatively wet and dry climate conditions, respectively. From ∼85 to 48 ka, sediments were dominated by carbonate clay indicating moist conditions during Marine Isotope Stages (MIS) 5a, 4, and early 3. The first gypsum layer was deposited at ∼48 ka, signifying a shift toward drier hydrologic conditions and the onset of wet–dry oscillations. During the latter part of MIS 3, Petén climate varied between wetter conditions during interstadials and drier states during stadials. The pattern of clay–gypsum (wet–dry) oscillations during the latter part of MIS 3 (∼48–23 ka) closely resembles the temperature records from Greenland ice cores and North Atlantic marine sediment cores and precipitation proxies from the Cariaco Basin. The most arid periods coincided with Heinrich Events when cold sea surface temperatures prevailed in the North Atlantic, meridional overturning circulation was reduced, and the Intertropical Convergence Zone (ITCZ) was displaced southward. A thick clay unit was deposited from 23 to 18 ka suggesting deposition in a deep lake, and pollen accumulated during the same period indicates vegetation consisted of a temperate pine-oak forest. This finding contradicts previous inferences that climate was arid during the Last Glacial Maximum (LGM) chronozone (21±2 ka). At ∼18 ka, Petén climate switched from moist to arid conditions and remained dry from 18 to 14.7 ka during the early deglaciation. Moister conditions prevailed during the warmer Bolling–Allerod (14.7–12.8 ka) with the exception of a brief return to dry conditions at ∼13.8 ka that coincides with the Older Dryas and meltwater pulse 1A. The onset of the Younger Dryas at 12.8 ka marked the return of gypsum and hence dry conditions. The lake continued to precipitate gypsum until ∼10.3 ka when rainfall increased markedly in the early Holocene.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.quascirev.2008.02.008
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Millennial hydrological variability in the continental northern Neotropics during Marine Isotope Stages (MISs) 3–2 (59–15 cal ka BP) inferred from sediments of Lake Petén Itzá, Guatemala (2023)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-02-07
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    (Table 1) Age determination of sediment core MD02-2551 (2006)
    PANGAEA
    In:  Supplement to: Hill, Heather W; Flower, Benjamin P; Quinn, Terrence Michael; Hollander, David J; Guilderson, Thomas P (2006): Laurentide Ice Sheet meltwater and abrupt climate change during the last glaciation. Paleoceanography, 21(1), PA1006, https://doi.org/10.1029/2005PA001186
    Details
    Publication Date: 2023-11-04
    Description: A leading hypothesis to explain abrupt climate change during the last glacial cycle calls on fluctuations in the margin of the North American Laurentide Ice Sheet (LIS), which may have routed fresh water between the Gulf of Mexico (GOM) and the North Atlantic, affecting North Atlantic Deep Water variability and regional climate. Paired measurements of d18O and Mg/Ca of foraminiferal calcite from GOM sediments reveal five episodes of LIS meltwater input from 28 to 45 thousand years ago (ka) that do not match the millennial-scale Dansgaard-Oeschger warmings recorded in Greenland ice. We suggest that summer melting of the LIS may occur during Antarctic warming and likely contributed to sea level variability during marine isotope stage 3.
    Keywords: Age, 14C AMS; Age, 14C calibrated; Age, comment; Age, dated; Age, dated standard error; Calendar age; CALYPSO; Calypso Corer; DEPTH, sediment/rock; IMAGES IX - PAGE; Laboratory code/label; Marion Dufresne (1995); MD022551; MD02-2551; MD127; Orca Basin
    Type: Dataset
    Format: text/tab-separated-values, 90 data points
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    DATA PANGAEA
  • 8
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    (Table 1) Age determination of surface sediment samples from the North Atlantic (2009)
    PANGAEA
    In:  Supplement to: Keigwin, Lloyd D; Guilderson, Thomas P (2009): Bioturbation artifacts in zero-age sediments. Paleoceanography, 24(4), PA4212, https://doi.org/10.1029/2008PA001727
    Details
    Publication Date: 2023-11-04
    Description: Most seafloor sediments are dated with radiocarbon, and the sediment is assumed to be zero-age (modern) when the signal of atmospheric testing of nuclear weapons is present (Fraction modern (Fm) 〉 1). Using a simple mass balance, we show that even with Fm 〉 1, half of the planktonic foraminifera at the seafloor can be centuries old, because of bioturbation. This calculation, and data from four core sites in the western North Atlantic indicate that, first, during some part of the Little Ice Age (LIA) there may have been more Antarctic Bottom Water than today in the deep western North Atlantic. Alternatively, bioturbation may have introduced much older benthic foraminifera into surface sediments. Second, paleo-based warming of Sargasso Sea surface waters since the LIA must lag the actual warming because of bioturbation of older and colder foraminifera.
    Keywords: Age, 14C AMS; Age, dated; Age, dated material; Age, dated standard deviation; BC; Box corer; DEPTH, sediment/rock; Elevation of event; Event label; Fraction modern carbon; Fraction modern carbon, error; Knorr; KNR178; KNR178-1-1-1; Laboratory code/label; Latitude of event; Longitude of event; MUC; MultiCorer; North Atlantic; OCE326-BC9; OCE326-MC13; OCE326-MC25; Reference/source; Δ14C
    Type: Dataset
    Format: text/tab-separated-values, 51 data points
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    DATA PANGAEA
  • 9
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    (Table 1) Age-depth relation in sediment core TTN057-13-PC4 (2002)
    PANGAEA
    In:  Supplement to: Shemesh, Aldo; Hodell, David A; Crosta, Xavier; Kanfoush, Sharon L; Charles, Christopher D; Guilderson, Thomas P (2002): Sequence of events during the last deglaciation in Southern Ocean sediments and Antarctic ice cores. Paleoceanography, 17(4), 1056, https://doi.org/10.1029/2000PA000599
    Details
    Publication Date: 2023-11-04
    Description: The last glacial to interglacial transition was studied using down core records of stable isotopes in diatoms and foraminifera as well as surface water temperature, sea ice extent, and ice-rafted debris (IRD) concentrations from a piston core retrieved from the Atlantic sector of the Southern Ocean. Sea ice is the first variable to change during the last deglaciation, followed by nutrient proxies and sea surface temperature. This sequence of events is independent of the age model adopted for the core. The comparison of the marine records to Antarctic ice CO2 variation depends on the age model as 14C determinations cannot be obtained for the time interval of 29.5-14.5 ka. Assuming a constant sedimentation rate for this interval, our data suggest that sea ice and nutrient changes at about 19 ka B.P. lead the increase in atmospheric pCO2 by approximately 2000 years. Our diatom-based sea ice record is in phase with the sodium record of the Vostok ice core, which is related to sea ice cover and similarly leads the increase in atmospheric CO2. If gas exchange played a major role in determining glacial to interglacial CO2 variations, then a delay mechanism of a few thousand years is needed to explain the observed sequence of events. Otherwise, the main cause of atmospheric pCO2 change must be sought elsewhere, rather than in the Southern Ocean.
    Keywords: Age, 14C AMS; Age, 14C calibrated; Age, dated; Age, dated standard deviation; Calendar age; DEPTH, sediment/rock; PC; Piston corer; Reference/source; Sample code/label; TN057-13-PC4
    Type: Dataset
    Format: text/tab-separated-values, 74 data points
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    DATA PANGAEA
  • 10
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    (Table 3) Age determination and calculated growth rates of corals (2014)
    PANGAEA
    Details
    Publication Date: 2023-11-04
    Keywords: Age, dated; Age, dated material; Age, dated standard deviation; DISTANCE; Event label; Growth rate; Growth rate, standard deviation; Maximum; Minimum; Remote operated vehicle; ROV; T661_A9; T664_A17; Δ14C; Δ14C, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 50 data points
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    DATA PANGAEA
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