A new 30 000-year chronology for rapidly deposited sediments on the Lomonosov Ridge using bulk radiocarbon dating and probabilistic stratigraphic alignment

Abstract. We present a new marine chronostratigraphy from a high-accumulation rate Arctic Ocean core at the intersection of the Lomonosov Ridge and the Siberian margin, spanning the last ∼30 kyr. The chronology was derived using a combination of bulk 14C dating and stratigraphic correlation to Greenland ice-core records. This was achieved by applying an appositely developed Markov chain Monte Carlo algorithm for Bayesian probabilistic alignment of proxy records. The algorithm simulates depositionally realistic alignments that are consistent with the available radiocarbon age estimates and allows deriving uncertainty bands associated with the inferred alignment. Current composite chronologies from this region are reasonably consistent with our age model during the Holocene and the latter part of deglaciation. However, prior to ∼14 kyr BP they yield too old age estimates with offsets that linearly increase up to ∼40 kyr near the onset of Marine Isotope Stage (MIS) 2. Our results challenge the robustness of previous regional chronostratigraphies and provide a new stratotype for correlation of sediment cores from this sector of the Lomonosov Ridge and East Siberian slope. In particular, they call for a re-interpretation of events in recent sea-ice proxy reconstructions (Xiao et al., 2015) inaccurately attributed to MIS-3 and the Last Glacial Maximum.

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High-resolution radiocarbon dating to reconstruct last century environmental changes in the pacific island of Espiritu Santo

10.5194/egusphere-egu21-15449 ◽

2021 ◽

Author(s):

Giorgia Camperio ◽

Caroline Welte ◽

S. Nemiah Ladd ◽

Matthew Prebble ◽

Nathalie Dubois

Keyword(s):

High Resolution ◽

Radiocarbon Dating ◽

Environmental Changes ◽

Accumulation Rate ◽

Sediment Cores ◽

Volcanic Eruptions ◽

High Accumulation ◽

Sedimentary Records ◽

The Pacific ◽

Rapid Accumulation

<p>Espiritu Santo is one of the 82 islands of the archipelago of Vanuatu and is the largest, highest, and most biodiverse of the insular country. Climatic changes linked to El Ni&#241;o and extreme events such as cyclones and volcanic eruptions are a daily challenge in this remote area. These events can be recorded in sedimentary archives. Here we present a multi-proxy investigation of sediment cores retrieved from two small lakes located on the West coast of Espiritu Santo. Although the records span the last millennium, high-resolution radiocarbon dating of macrofossils reveals a rapid accumulation of sediment in the past 100 years. The high accumulation rate coupled with the high-resolution dating of freshwater sediments allows us to compare the <sup>14</sup>C bomb curve with the biogeochemical proxies of the sedimentary records. The results can then be validated against written and oral historical records linked with the societal perception of recent environmental changes in this vulnerable ecosystem.</p><div> <div title="Translate selected text"></div> <div title="Play"></div> <div title="Copy text to Clipboard"></div> </div>

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Evidence for a hardwater radiocarbon dating effect, Wonder Lake, Denali national park and preserve, Alaska, U.S.A.

Géographie physique et Quaternaire ◽

10.7202/004780ar ◽

2002 ◽

Vol 53 (3) ◽

pp. 407-411 ◽

Cited By ~ 5

Author(s):

Jonathan K. Child ◽

Al Werner

Keyword(s):

National Park ◽

Sediment Cores ◽

Pollen Record ◽

Lake Area ◽

Alaska Range ◽

Radiocarbon Age ◽

The North ◽

Late Wisconsinan ◽

Denali National Park ◽

Age Estimates

Abstract Anderson et al. (1994) present a late Pleistocene/Holocene pollen record for lacustrine sediment cores retrieved from the north end of Wonder Lake, Denali National Park and Preserve, Alaska. Bulk radiocarbon age estimates obtained during their study suggest that either a Picea refugium persisted in the foothills of the north Alaska Range near Wonder Lake during the Late Wisconsinan, or that bulk radiocarbon age estimates are inaccurate. Subsequent cores recovered from Wonder Lake (and a near-by kettle pond) have been correlated to the Anderson et al. core and age dated using Atomic Mass Spectrometry (AMS) radiocarbon age estimates. AMS radiocarbon ages suggest that bulk radiocarbon ages from Anderson et al. (1994) are affected by hardwater conditions in Wonder Lake causing them to appear greater than 2000 14 C years too old. The corrected core chronology is consistent with documented regional vegetation changes during the glacial/interglacial transition and does not require a local Picea refugium in the Wonder Lake area during the Late Wisconsinan.

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A continuous 250-year record of volcanic activity from Princess Elizabeth Land, East Antarctica

Antarctic Science ◽

10.1017/s0954102002000573 ◽

2002 ◽

Vol 14 (1) ◽

pp. 55-60 ◽

Cited By ~ 21

Author(s):

M.J. Zhang ◽

Z.Q. Li ◽

C.D. Xiao ◽

D.H. Qin ◽

H.A. Yang ◽

...

Keyword(s):

Volcanic Activity ◽

Major Ions ◽

Accumulation Rate ◽

Ice Core ◽

Volcanic Eruptions ◽

East Antarctica ◽

Mean Annual Temperature ◽

High Definition ◽

Concentration Data ◽

High Accumulation

A 51.85 m ice core collected from site LGB65 (accumulation rate 127 kg m−2 a−1, mean annual temperature −33.1°C) in Princess Elizabeth Land, East Antarctica, during the 1996–97 Chinese First Antarctic Inland Expedition has been analysed for chemical composition and oxygen isotope ratio. Based on the high definition of seasonal variations of major ions, the ice core was dated with errors within ± 3 years. The continuous sulphate analysis of the ice core provides an annually resolved proxy history of southern hemisphere volcanism in the past 250 years. High nssSO42−, concentrations seem to be well correlated to some explosive volcanic eruptions, such as Tambora (AD 1815), Coseguina (AD 1835), Krakatoa (AD 1883) and Tarawera (AD 1886). In comparison with other volcanic records, it seems that nssSO42− concentration data provide a better proxy for detecting volcanic activity than nssSO42− fluxes in low and intermediate accumulation regions, however, in high accumulation regions, small and moderate events may be more identifiable using of nssSO42− flux data.

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Isotopic diffusion in polar firn: implications for interpretation of seasonal climate parameters in ice-core records, with emphasis on central Greenland

Journal of Glaciology ◽

10.3189/s0022143000002616 ◽

1998 ◽

Vol 44 (147) ◽

pp. 273-284 ◽

Cited By ~ 1

Author(s):

Kurt M. Cuffey ◽

Eric J. Steig

Keyword(s):

Accumulation Rate ◽

A Priori ◽

Ice Core ◽

Published Data ◽

High Accumulation ◽

Proxy Records ◽

New Information ◽

Isotopic Records ◽

Diffusive Mixing ◽

Ice Core Records

AbstractIf it were possible to properly extract seasonal information from ice-core isotopic records, paleoclimate researchers could retrieve a wealth of new information concerning the nature of climate changes and the meaning of trends observed in ice-core proxy records. It is widely recognized, however, that the diffusional smoothing of the seasonal record makes a “proper extraction" very difficult. In this paper, we examine the extent to which seasonal information (specifically the amplitude and shape of the seasonal cycle) is irrecoverably destroyed by diffusion in the firn. First, we show that isotopic diffusion firn is reasonably well understood. We do this by showing that a slightly modified version of the Whillans and Grootes (1985) theory makes a tenable a priori prediction of the decay of seasonal isotopic amplitudes with depth at the GISP2 site, though a small adjustment to one parameter significantly improves the prediction. Further, we calculate the amplitude decay at various other ice-core sites and show that these predictions compare favorably with published data from South Pole and locations in southern and central Greenland and the Antarctic Peninsula. We then present numerical experiments wherein synthetic ice-core records are created, diffused, sampled, reconstituted and compared to the original. These show that, alter diffusive mixing in the entire fini column, seasonal amplitudes can be reconstructed to within about 20% error in central Greenland but that all information about sub-annual signals is permanently lost there. Furthermore, most of the error in the amplitude reconstructions is due to the unknowable variations in the sub-annual signal. Finally, we explore how these results can be applied to other locations and suggest that Dye 3 has a high potential for meaningful seasonal reconstructions, while Siple Dome has no potential at all. An optimal ice-core site for seasonal reconstructions has a high accumulation rate and a low temperature.

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Volcanic Fluxes Over the Last Millennium as Recorded in the Gv7 Ice Core (Northern Victoria Land, Antarctica)

Geosciences ◽

10.3390/geosciences10010038 ◽

2020 ◽

Vol 10 (1) ◽

pp. 38 ◽

Cited By ~ 3

Author(s):

Raffaello Nardin ◽

Alessandra Amore ◽

Silvia Becagli ◽

Laura Caiazzo ◽

Massimo Frezzotti ◽

...

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Ice Cores ◽

Volcanic Eruptions ◽

Deposition Flux ◽

Last Millennium ◽

Regional Variability ◽

High Accumulation ◽

Continental Scale ◽

Victoria Land

Major explosive volcanic eruptions may significantly alter the global atmosphere for about 2–3 years. During that period, volcanic products (mainly H2SO4) with high residence time, stored in the stratosphere or, for shorter times, in the troposphere are gradually deposited onto polar ice caps. Antarctic snow may thus record acidic signals providing a history of past volcanic events. The high resolution sulphate concentration profile along a 197 m long ice core drilled at GV7 (Northern Victoria land) was obtained by Ion Chromatography on around 3500 discrete samples. The relatively high accumulation rate (241 ± 13 mm we yr −1) and the 5-cm sampling resolution allowed a preliminary counted age scale. The obtained stratigraphy covers roughly the last millennium and 24 major volcanic eruptions were identified, dated, and tentatively ascribed to a source volcano. The deposition flux of volcanic sulphate was calculated for each signature and the results were compared with data from other Antarctic ice cores at regional and continental scale. Our results show that the regional variability is of the same order of magnitude as the continental one.

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The Paleochrono probabilistic model to derive a consistent chronology for several paleoclimatic sites

10.5194/egusphere-egu21-822 ◽

2021 ◽

Author(s):

Frédéric Parrenin ◽

Lucie Bazin ◽

Christo Buizert ◽

Emilie Capron ◽

Jai Chowdry Beeman ◽

...

Keyword(s):

Probabilistic Model ◽

Environmental Changes ◽

Accumulation Rate ◽

Ice Core ◽

Sediment Cores ◽

Computing Time ◽

Ice Cores ◽

Ease Of Use ◽

Sequence Of Events ◽

Different Types

<p>Past climatic and environmental changes can be reconstructed thanks to paleoclimatic archives such as ice cores, marine sediment cores, lake sediment cores, speleothems, tree rings, corals, etc. The dating of these natural archives is crucial for deciphering the temporal sequence of events during past climate changes. It is also essential to estimate the absolute and relative errors of such estimated chronologies. This task is, however, complex since it involves the combination of different dating approaches on different paleoclimatic sites and often different types of archives. Here we present Paleochrono, a new probabilistic model to derive a common and probalistically optimal chronology for several paleoclimatic sites with potentially different types of archives. Paleochrono is based on the inversion of an archiving model: a varying deposition rate (also named sedimentation or accumulation rate) and also,&#160;for ice cores, a&#160;lock-in-depth of air bubbles (since air is not trapped at surface) and a thinning function (since ice undergoes flow).&#160;The model integrates several types of chronological information: prior knowledge of the archiving process, independently dated horizons, depth intervals of known duration, undated stratigraphic links between records, and, for ice cores, &#916;depth observations (depth differences between synchronous events recorded in the bubbles and ice, respectively). The optimization is formulated as a least-squares problem, assuming that all densities of probabilities are near-Gaussian and that the model is almost linear in the vicinity of the best solution. Paleochrono is the successor of IceChrono, which was dealing only with ice-core records. Paleochrono&#160;performs better than IceChrono in terms of computational efficiency, ease of use, and accuracy. We demonstrate the ability of Paleochrono in a new AICC2012-Hulu dating experiment, which combines the AICC2012 dating experiment, based on records from five polar ice cores,&#160;with data from two U/Th-dated speleothems from Hulu Cave (China). We analyse the performance of Paleochrono in terms of computing time and memory usage in various dating experiments. Paleochrono is freely available under the MIT open source license.</p>

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Changes in tropospheric methane between 1841 and 1978 from a high accumulation-rate Antarctic ice core

Tellus B ◽

10.1034/j.1600-0889.1992.t01-3-00006.x ◽

1992 ◽

Vol 44 (4) ◽

pp. 282-294 ◽

Cited By ~ 116

Author(s):

D. M. ETHERIDGE ◽

G. I. PEARMAN ◽

P. J. FRASER

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

High Accumulation

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Isotopic diffusion in polar firn: implications for interpretation of seasonal climate parameters in ice-core records, with emphasis on central Greenland

Journal of Glaciology ◽

10.1017/s0022143000002616 ◽

1998 ◽

Vol 44 (147) ◽

pp. 273-284 ◽

Cited By ~ 57

Author(s):

Kurt M. Cuffey ◽

Eric J. Steig

Keyword(s):

Accumulation Rate ◽

A Priori ◽

Ice Core ◽

Published Data ◽

High Accumulation ◽

Proxy Records ◽

New Information ◽

Isotopic Records ◽

Diffusive Mixing ◽

Ice Core Records

AbstractIf it were possible to properly extract seasonal information from ice-core isotopic records, paleoclimate researchers could retrieve a wealth of new information concerning the nature of climate changes and the meaning of trends observed in ice-core proxy records. It is widely recognized, however, that the diffusional smoothing of the seasonal record makes a “proper extraction" very difficult. In this paper, we examine the extent to which seasonal information (specifically the amplitude and shape of the seasonal cycle) is irrecoverably destroyed by diffusion in the firn. First, we show that isotopic diffusion firn is reasonably well understood. We do this by showing that a slightly modified version of the Whillans and Grootes (1985) theory makes a tenable a priori prediction of the decay of seasonal isotopic amplitudes with depth at the GISP2 site, though a small adjustment to one parameter significantly improves the prediction. Further, we calculate the amplitude decay at various other ice-core sites and show that these predictions compare favorably with published data from South Pole and locations in southern and central Greenland and the Antarctic Peninsula. We then present numerical experiments wherein synthetic ice-core records are created, diffused, sampled, reconstituted and compared to the original. These show that, alter diffusive mixing in the entire fini column, seasonal amplitudes can be reconstructed to within about 20% error in central Greenland but that all information about sub-annual signals is permanently lost there. Furthermore, most of the error in the amplitude reconstructions is due to the unknowable variations in the sub-annual signal. Finally, we explore how these results can be applied to other locations and suggest that Dye 3 has a high potential for meaningful seasonal reconstructions, while Siple Dome has no potential at all. An optimal ice-core site for seasonal reconstructions has a high accumulation rate and a low temperature.

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The climate signal recorded in the oxygen-isotope, accumulation and major-ion time series from the Eclipse ice core, YukonTerritory, Canada

Annals of Glaciology ◽

10.3189/172756402781817266 ◽

2002 ◽

Vol 35 ◽

pp. 416-422 ◽

Cited By ~ 27

Author(s):

Cameron P. Wake ◽

Kaplan Yalcin ◽

Niels S. Gundestrup

Keyword(s):

Time Series ◽

Sea Level ◽

Accumulation Rate ◽

Ice Core ◽

Yukon Territory ◽

High Accumulation ◽

Sea Level Pressure ◽

Climate Signal ◽

Level Pressure ◽

Cross Correlation Analysis

AbstractThe high accumulation rate, nearly complete preservation and detailed chronology of the Eclipse ice core, Yukon Territory, Canada, are well suited for comparison of the glaciochemical recordwith instrumental time series of temperature, precipitation and sea-level pressure. Results of cross-correlation analysis of instrumental temperature records with the Eclipse δ18O time series reveal a significant positive relationship between summertime δ18O at Eclipse and summer (April–September) temperatures in northwestern North America. the results indicate that the Eclipse δ18O time series provides a better proxy for regional temperature than does the δ18O time series from the Mount Logan ice-core record for which only negative correlations were found. Winter accumulation at Eclipse is significantly correlated with several sites in Alaska, but not with any sites in the Yukon. the δ18O, accumulation and glaciochemical time series also display significant correlations with the Northern Hemisphere sea-level pressure dataset, especially between wintertime sulfate and nitrate concentrations at Eclipse and the intensity of the wintertime Siberian high and Aleutian and Icelandic lows. These results suggest that year-to-year variability in the deposition of pollutants at Eclipse can be linked to changes in atmospheric circulation, while long-term trends can be explained by changes in source strength.

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