Dating the Siple Dome (Antarctica) ice core by manual and computer interpretation of annual layering

AbstractThe Holocene portion of the Siple Dome (Antarctica) ice core was dated by interpreting the electrical, visual and chemical properties of the core. The data were interpreted manually and with a computer algorithm. The algorithm interpretation was adjusted to be consistent with atmospheric methane stratigraphic ties to the GISP2 (Greenland Ice Sheet Project 2) ice core, 10Be stratigraphic ties to the dendrochronology 14 C record and the dated volcanic stratigraphy. The algorithm interpretation is more consistent and better quantified than the tedious and subjective manual interpretation.

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The Debris-Laden Ice at the Bottom of the Greenland Ice Sheet

Journal of Glaciology ◽

10.3189/s002214300002983x ◽

1979 ◽

Vol 23 (89) ◽

pp. 193-207 ◽

Cited By ~ 24

Author(s):

Susan Herron ◽

Hoar ◽

Chester C. Langway

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

High Deformation ◽

Fine Grained ◽

Free Zone ◽

The Core ◽

Oxidation Of Methane ◽

Particle Aggregates ◽

Glacier Ice

AbstractThe Camp Century, Greenland, ice core was recovered from a bore hole which extended 1 375 m from the surface of the Greenland ice sheet to the ice/sub-ice interface. The bottom 15.7 m of the core contain over 300 alternating bands of clear and debris-laden ice. The size of the included debris ranges from particles less than 2 μm in diameter to particle aggregates which are a maximum of 3 cm in diameter: the average debris concentration is 0.24ºº by weight. The debris size, concentration, and composition indicate that the debris originates from the till-like material directly below the debris-laden ice. The total gas concentration averages 51 ml/kg ice compared to the average of 101 ml/kg ice for the top 1 340 m. The gas composition of debris-bearing ice has apparently been modified by the oxidation of methane as reflected by traces of methane, high CO2 levels, and low O2 levels with respect to atmospheric air. Argon, which is not affected by the oxidation, shows an enrichment in samples with lower gas concentrations. Both the low gas concentrations in the debris-laden zone and the argon enrichment may be explained by the downward diffusion of gases from bubbly glacier ice into an originally bubble-free zone of refrozen debris-laden ice. Ice texture and ice-fabric analyses reveal extremely fine-grained ice and highly preferred crystal orientation in the lowermost 10 m of the core, indicating a zone of high deformation.

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Forty years later: High resolution continuous flow analysis of the Dye3 ice core

10.5194/egusphere-egu21-11820 ◽

2021 ◽

Author(s):

Helle Astrid Kjær ◽

Margaret Harlan ◽

Paul Vallelonga ◽

Anders Svensson ◽

Thomas Blunier ◽

...

Keyword(s):

High Resolution ◽

Forest Fires ◽

Continuous Flow ◽

Ice Core ◽

Flow Analysis ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Cores ◽

The Core ◽

Continuous Flow Analysis

<div>The Dye-3 ice core was drilled to bedrock at the Southern part of the central Greenland ice sheet (65&#176;11'N, 43&#176;50'W) in 1979-1981. The southern location is characterized by high accumulation rates compared to more central locations of the ice sheet. Since its drilling, numerous analyses of the core have been performed, and the ice has since been in freezer storage both in the USA and in Denmark.</div><div>In October and November 2019, the remaining ice, two mostly complete sections covering the depths of 1753&#8211;1820m and 1865&#8211;1918m of the Dye-3 core, were melted during a continuous flow analysis (CFA) campaign at the Physics of Ice, Climate, and Earth (PICE) group at the University of Copenhagen. The data represents both Holocene, Younger Dryas and Glacial sections (GS 5 to 12).</div><div>&#160;</div><div>The measured data consist chemistry and impurities contained in the ice, isotopes, as well as analysis of methane and other atmospheric gases.&#160;</div><div>The chemistry measurements include NH4+, Ca2+, and Na+&#160;ions, which besides being influenced by transport, provide information about forest fires, wind-blown dust, and sea ice, respectively, as well as acidity, which aids in the identification of volcanic events contained in the core. The quantity and grain size distribution of insoluble particles was analyzed by means of an Abakus laser particle counter.</div><div>&#160;</div><div>We compare the new high-resolution CFA record of dye3 with previous analysis and thus evaluate the progress made over 40 years. Further we compare overlapping time periods with other central Greenland ice cores and discuss spatial patterns in relation to the presented climate proxies.</div>

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Tracing the depth of the Holocene ice in North Greenland from radio-echo sounding data

Annals of Glaciology ◽

10.3189/2013aog64a057 ◽

2013 ◽

Vol 54 (64) ◽

pp. 44-50 ◽

Cited By ~ 25

Author(s):

Nanna B. Karlsson ◽

Dorthe Dahl-Jensen ◽

S. Prasad Gogineni ◽

John D. Paden

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Cores ◽

The Holocene ◽

Fitting Method ◽

Radio Echo Sounding ◽

North Greenland ◽

Echo Sounding

Abstract Radio-echo sounding surveys over the Greenland ice sheet show clear, extensive internal layering, and comparisons with age–depth scales from deep ice cores allow for dating of the layering along the ice divide. We present one of the first attempts to extend the dated layers beyond the ice core drill sites by locating the depth of the Bølling–Allerød transition in >400 flight-lines using an automated fitting method. Results show that the transition is located in the upper one-third of the ice column in the central part of North Greenland, while the transition lowers towards the margin. This pattern mirrors the present surface accumulation, and also indicates that a substantial amount of pre-Holocene ice must be present in central North Greenland.

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Potential for stratigraphie folding near ice-sheet centers

Journal of Glaciology ◽

10.3189/172756501781831756 ◽

2001 ◽

Vol 47 (159) ◽

pp. 639-648 ◽

Cited By ~ 29

Author(s):

Edwin D. Waddington ◽

John F. Bolzan ◽

Richard B. Alley

Keyword(s):

Transient Flow ◽

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Cores ◽

Climate Record ◽

Bed Topography ◽

Flow Disturbances ◽

Siple Dome ◽

Ice Core Record

AbstractLack of agreement between the deep portions of the Greenland Icecore Project (GRIP) and Greenland Ice Sheet Project II (GISP2) ice cores from central Greenland suggests that folds may disrupt annual layering, even near ice divides. We use a simple kinematic flow model to delineate regions where slope disturbances (“wrinkles”) introduced into the layering could overturn into recumbent folds, and where they would flatten, leaving the stratigraphic record intact. Wrinkles are likely to originate from flow disturbances caused internally by inhomogeneities and anisotropy in the ice rheological properties, rather than from residual surface structures (sastrugi), or from open folds associated with transient flow over bed topography. If wrinkles are preferentially created in anisotropic ice under divides, where the resolved shear stress in the easy-glide direction can be weak and variable, then the deep intact climate record at Dye 3 may result from its greater distance from the divide. Alternatively, the larger simple shear at Dye 3 may rapidly overturn wrinkles, so that they are not recognizable as folds. The ice-core record from Siple Dome may be intact over a greater fraction of its depth compared to the central Greenland records if its flat bedrock precludes fluctuations in the stress orientation near the divide.

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Holocene history of the Greenland ice sheet based on radiocarbon-dated moraines in West Greenland

Bulletin Grønlands Geologiske Undersøgelse ◽

10.34194/bullggu.v113.6654 ◽

1975 ◽

Vol 113 ◽

pp. 1-44

Author(s):

N.W.T Brink

Keyword(s):

Marine Sediments ◽

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Dynamic Responses ◽

Geological Evidence ◽

Sea Levels ◽

The Holocene ◽

West Greenland ◽

Inland Ice

The Greenland ice sheet margin retreated at least 125 km in West Greenland during the Holocene, but frequent halts or readvances interrupted the general trend and formed extensive moraine systems. Local deglaciation was synchronous with marine invasion of the fjords, resulting in deposition of interrelated glacial and marine sediments. The marine deposits have been uplifted by postglacial isostatic rebound and now occur as emerged-marine sediments and strandlines up to 125 ± 5 m a.s.l. The age and altitude values of 21 radiocarbon-dated samples of mollusc shells collected from the emerged-marine sediments define two postglacial emergence curves, which have been used to date moraine systems by means of their relations to former relative sea levels. Major moraine systems were constructed by the inland ice about 8800 B.P., 8300 B.P., 7300 B.P., 6500 B.P. to perhaps 6000(?) B.P., and presumably c. 4800- 4000 B.P. and 2500-2000 B.P. An advance of the inland ice about 3 km beyond its present margin c. 700 lichenometric years B.P. was followed by oscillatory retreat and advance, culminated by an advance 330 ± 75 C-H years B. P. Moraines adjacent to the present ice margin were formed by a series of small advances culminated by local maxima between A.D. 1880 and 1920. The episodes of moraine construction were probably caused by slight decreases in mean temperature over periods of several decades to a few centuries, resulting in decreased ablation and immediate growth of the ice sheet margin. Long-term dynamic responses of the entire ice sheet, requiring thousands of years, were not necessary to form the moraines. The suggested short-term climatic cause of Holocene moraine construction is supported by palynologic and regional glacial geological evidence as well as historic temperature-glacier relations in West Greenland. Net retreat of the ice sheet margin during the Holocene was almost undoubtedly caused by hemisphere-wide climatic warming recorded in the 018/016 data for the Camp Century, Greenland, ice core as well as palynologic data from several sites in the Northern Hemisphere.

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Geological, geochemical and cosmogenic nuclides constraints from the NEEM core basal sediments, Greenland

10.5194/egusphere-egu2020-18143 ◽

2020 ◽

Author(s):

Marie Protin ◽

Pierre-Henri Blard ◽

Jean-Louis Tison ◽

Dorthe Dahl-Jensen ◽

Jørgen Steffensen ◽

...

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Cosmogenic Nuclides ◽

Carbon And Nitrogen ◽

The Core ◽

Basal Ice ◽

C And N ◽

Mixed Origin ◽

Shape Characterization

As the melting of the Greenland Ice Sheet (GrIS) accelerates, it is critical to improve our knowledge of its Pleistocene history in order to better understand its sensitivity to different climate states. The study of sediment from the base of the ice sheet offers valuable insights, since this material holds useful information about its history and origin. Here, we present various mineralogical and geochemical analysis from basal sediments of the NEEM ice core from northwestern Greenland (NEEM community, 2013), a complement to the first analysis of the basal ice made by Goossens et al. (2016).In an effort to specify the provenance and characterize the sediments in the basal ice of the NEEM ice core, strontium and neodymium isotopic ratios were measured in 7 bulk till samples located into the deepest part of the core. Laser granulometry and shape characterization by SEB images of the grains suggest a mixed origin of this material. The deepest sample yield in situ cosmogenic 10Be and 26Al concentrations lower than 104 at.g-1 and 21Ne concentration in the 107-108 at.g-1 range. These preliminary cosmogenic nuclides data suggest that several cycles of waning and waxing of the GrIS had occurred over the last 10 million years. Additional sample material is being processed to reduce the uncertainty of 26Al and 10Be measurements and refine this chronology.To better characterize the origin of the basal sediment and the duration of pre-burial exposure, measurements of meteoric cosmogenic 10Be in 7 samples distributed along the basal part of the core are currently in progress. These data will be combined with the measurement of total organic carbon and nitrogen in the same samples. C and N concentrations and isotopes bring useful information about the type of soil and till material in these basal sediments (Bierman et al., 2016).&#160;Bierman, P.R., Shakun, J.D., Corbett, L.B., Zimmerman, S.R., Rood, D.H., 2016. A persistent and dynamic East Greenland Ice Sheet over the past 7.5 million years. Nature 540, 256&#8211;260. https://doi.org/10.1038/nature20147Goossens, T., Sapart, C.J., Dahl-Jensen, D., Popp, T., El Amri, S., Tison, J.-L., 2016. A comprehensive interpretation of the NEEM basal ice build-up using a multi-parametric approach. The Cryosphere 10, 553&#8211;567. https://doi.org/10.5194/tc-10-553-2016NEEM community, 2013. Eemian interglacial reconstructed from a Greenland folded ice core. Nature, 493. doi:10.1038/nature11789

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The Debris-Laden Ice at the Bottom of the Greenland Ice Sheet

Journal of Glaciology ◽

10.1017/s002214300002983x ◽

1979 ◽

Vol 23 (89) ◽

pp. 193-207 ◽

Cited By ~ 56

Author(s):

Susan Herron ◽

Hoar ◽

Chester C. Langway

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

High Deformation ◽

Fine Grained ◽

Free Zone ◽

The Core ◽

Oxidation Of Methane ◽

Particle Aggregates ◽

Glacier Ice

Abstract The Camp Century, Greenland, ice core was recovered from a bore hole which extended 1 375 m from the surface of the Greenland ice sheet to the ice/sub-ice interface. The bottom 15.7 m of the core contain over 300 alternating bands of clear and debris-laden ice. The size of the included debris ranges from particles less than 2 μm in diameter to particle aggregates which are a maximum of 3 cm in diameter: the average debris concentration is 0.24º º by weight. The debris size, concentration, and composition indicate that the debris originates from the till-like material directly below the debris-laden ice. The total gas concentration averages 51 ml/kg ice compared to the average of 101 ml/kg ice for the top 1 340 m. The gas composition of debris-bearing ice has apparently been modified by the oxidation of methane as reflected by traces of methane, high CO2 levels, and low O2 levels with respect to atmospheric air. Argon, which is not affected by the oxidation, shows an enrichment in samples with lower gas concentrations. Both the low gas concentrations in the debris-laden zone and the argon enrichment may be explained by the downward diffusion of gases from bubbly glacier ice into an originally bubble-free zone of refrozen debris-laden ice. Ice texture and ice-fabric analyses reveal extremely fine-grained ice and highly preferred crystal orientation in the lowermost 10 m of the core, indicating a zone of high deformation.

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The effect of a Holocene climatic optimum on the evolution of the Greenland ice sheet during the last 10 kyr

Journal of Glaciology ◽

10.1017/jog.2018.40 ◽

2018 ◽

Vol 64 (245) ◽

pp. 477-488 ◽

Cited By ~ 5

Author(s):

LISBETH T. NIELSEN ◽

GUðFINNA AÐALGEIRSDÓTTIR ◽

VASILEIOS GKINIS ◽

ROMAN NUTERMAN ◽

CHRISTINE S. HVIDBERG

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Early Holocene ◽

Climate Forcing ◽

The Holocene ◽

The Past ◽

Holocene Climatic Optimum ◽

Surface Temperatures ◽

Climatic Optimum

ABSTRACTThe Holocene climatic optimum was a period 8–5 kyr ago when annual mean surface temperatures in Greenland were 2–3°C warmer than present-day values. However, this warming left little imprint on commonly used temperature proxies often used to derive the climate forcing for simulations of the past evolution of the Greenland ice sheet. In this study, we investigate the evolution of the Greenland ice sheet through the Holocene when forced by different proxy-derived temperature histories from ice core records, focusing on the effect of sustained higher surface temperatures during the early Holocene. We find that the ice sheet retreats to a minimum volume of ~0.15–1.2 m sea-level equivalent smaller than present in the early or mid-Holocene when forcing an ice-sheet model with temperature reconstructions that contain a climatic optimum, and that the ice sheet has continued to recover from this minimum up to present day. Reconstructions without a warm climatic optimum in the early Holocene result in smaller ice losses continuing throughout the last 10 kyr. For all the simulated ice-sheet histories, the ice sheet is approaching a steady state at the end of the 20th century.

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Late Holocene thermohaline perturbation of the N-Atlantic Subpolar Gyre linked to exceptional Greenland Ice Sheet melting between 4.4 and 4.0 ka BP

10.5194/egusphere-egu2020-3103 ◽

2020 ◽

Author(s):

Antoon Kuijpers ◽

Marit-Solveig Seidenkrantz ◽

Ralph Schneider ◽

Camilla S. Andresen ◽

Signe Hygom Jacobsen ◽

...

Keyword(s):

Late Holocene ◽

Deep Convection ◽

Water Discharge ◽

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Subpolar Gyre ◽

The Holocene ◽

Master Thesis ◽

The Impact

Knowledge of the impact of past climate warming on Greenland Ice Sheet stability is an important issue for assessing &#160;thresholds that are critical for a potential ice sheet collapse. For the late Holocene, evidence has recently been found of a so-called 4.2 ka BP event(1) including a prominent warming spike in several ice core records from Greenland and Canada (Agassiz). &#160;Also lake records from both Northwest(2) and South Greenland(3) support pronounced summer warming during that time. After c. 4.0 ka BP NW Greenland July air temperature dropped by about 3o C. Coeval with this exceptional atmospheric warming anomaly over northern Canada and parts of Greenland, abrupt cooling and freshening affected &#160;the N-Atlantic subpolar gyre where Labrador Sea deep convection ceased(4). Northern N-Atlantic climate generally deteriorated. With our contribution we present Holocene sub-bottom profiling &#160;and sedimentary shelf and &#160;fjord records from Southwest Greenland and Disko Bay that indicate exceptional Greenland Ice Sheet melting 4.4-4.0 ka BP at a rate and magnitude not recorded since early Holocene deglaciation. Extremely strong melt water discharge resulted in erosion of fjord sediments(5) and local deposition of up to several meters thick meltwater sediment on the shelf(6-8). &#160;Timing of this melting event corresponds to a significant anomaly in hydrographic parameters of the Labrador Current off Newfoundland(9,10), which is concluded to have resulted in thermohaline perturbation of the N-Atlantic Subpolar gyre. &#160;&#160;<ul><li>(1) Weiss, H. 2019. Clim Past doi:10.5194/cp-2018-162-RC2</li> <li>(2) McFarlin, J.M. et al. 2018. PNAS doi:10.1073/pnas.1720420115</li> <li>(3) Andresen, C.S. et al. 2004. J Quat Sci 19(8) doi:10.1002/jqs.886</li> <li>(4) Klus, A. et al. 2018. Clim Past doi:10.5194/cp-14-1165-2018</li> <li>(5) Ren, J. et al. 2009. Mar Micropal doi:10.1016/j.marmicro.2008.12.003</li> <li>(6) Hygom Jacobsen, S. 2019. Master Thesis Aarhus Univ, Dept. of Geoscience, pp105</li> <li>(7) Schneider, R. 2015. Cruise Rep epic.awi.de/id/eprint/37062/131/msm-44-46-expeditionsheft.pdf</li> <li>(8) Kuijpers, A. et al. 2001. Geol. Greenland Surv Bull 189, 41-47</li> <li>(9) Solignac, S. et al. 2011. The Holocene, doi: 10.1177/0959683610385720</li> <li>(10) Orme, L. et al 2019. The Holocene (submitted)</li> </ul>

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Modelled Holocene thinning in Greenland improved by new developed transient past climatologies.

10.5194/egusphere-egu21-9846 ◽

2021 ◽

Author(s):

Ilaria Tabone ◽

Alexander Robinson ◽

Jorge Alvarez-Solas ◽

Javier Blasco ◽

Daniel Moreno ◽

...

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Model Parameters ◽

Last Deglaciation ◽

The Holocene ◽

Model Mismatch ◽

Elevation Changes ◽

The Impact

Reconstructions of Greenland Summit elevation changes indicate at least 150 m of surface thinning since the onset of the Holocene. Even higher thinning values are found at locations closer to the ice-sheet margin, where the influence of higher ablation rates and ocean-induced retreat is greater. Interestingly, the performance of 3D ice-sheet models in representing such elevation changes is generally poor, even though they can reasonably reproduce the state of the ice sheet at different times, such as the last glacial maximum (LGM) or the present day. The reasons behind this data-model mismatch are still unclear. Here we use a recently developed 3D ice-sheet-shelf model to test the impact of different model parameters and of boundary conditions on simulating the Greenland ice sheet evolution through the last deglaciation to today. Specifically, we investigate the role of past climatologies in reproducing the elevation changes at ice core sites when used to force the ice-sheet model. By applying recently developed transient deglacial climatologies we can investigate the ice-sheet deglaciation with exceptional detail. Results support the need of additional transient climatologies to be released to ensure a robust description of the Greenland retreat history throughout the Holocene.&#160;

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