New constraints on Greenland ice sheet dynamics during the last glacial cycle: Evidence from the Uummannaq ice stream system

Abstract. The presence of a grounded Greenland Ice Sheet on the northeastern part of the Greenland continental shelf during the Last Glacial Maximum is supported by new swath bathymetry and high-resolution seismic data, supplemented with multi-proxy analyses of sediment gravity cores from Store Koldewey Trough. Subglacial till fills the trough, with an overlying drape of maximum 2.5 m thick glacier-proximal and glacier-distal sediment. The presence of mega-scale glacial lineations and a grounding zone wedge in the outer part of the trough, comprising subglacial till, provides evidence of the expansion of fast-flowing, grounded ice, probably originating from the area presently covered with the Storstrømmen ice stream and thereby previously flowing across Store Koldewey Island and Germania Land. Grounding zone wedges and recessional moraines provide evidence that multiple halts and/or readvances interrupted the deglaciation. The formation of the grounding zone wedges is estimated to be at least 130 years, while distances between the recessional moraines indicate that the grounding line locally retreated between 80 and 400 m yr−1 during the deglaciation, assuming that the moraines formed annually. The complex geomorphology in Store Koldewey Trough is attributed to the trough shallowing and narrowing towards the coast. At a late stage of the deglaciation, the ice stream flowed around the topography on Store Koldewey Island and Germania Land, terminating the sediment input from this sector of the Greenland Ice Sheet to Store Koldewey Trough.

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Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum

Journal of Quaternary Science ◽

10.1002/jqs.1354 ◽

2009 ◽

Vol 25 (6) ◽

pp. 850-864 ◽

Cited By ~ 27

Author(s):

David H. Roberts ◽

Antony J. Long ◽

Bethan J. Davies ◽

Matthew J. R. Simpson ◽

Christoph Schnabel

Keyword(s):

Last Glacial Maximum ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Glacial Maximum ◽

West Greenland ◽

Last Glacial ◽

Ice Stream ◽

Ice Sheet Dynamics ◽

The Last Glacial Maximum ◽

The Last Glacial

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Modeling the Antarctic ice sheet

Annals of Glaciology ◽

10.1017/s0260305500014130 ◽

1997 ◽

Vol 25 ◽

pp. 259-268 ◽

Cited By ~ 4

Author(s):

Mikhail Verbitsky ◽

Barry Saltzman

Keyword(s):

Three Dimensional ◽

Ice Sheet ◽

Glacial Cycle ◽

Antarctic Ice Sheet ◽

Thermodynamic Equation ◽

Last Glacial ◽

Ice Stream ◽

Basal Melting ◽

The Antarctic ◽

The Last Glacial

A three-dimensional (3-D), high-resolution, non-linearly viscous, non-isothermal ice-sheet model is employed to calculate the “present-day” equilibrium regime of the Antarctic ice sheet and its evolution during the last glacial cycle. The model is augmented by an approximate formula for ice-sheet basal temperature, based on a scaling of the thermodynamic equation for the ice flow. Steady-state solutions for both the shape and extent of the areas of basal melting (or freezing) are shown to be in good agreement with those obtained from the solution of the full 3-D thermodynamic equation. The solution for the basal temperature field of the West Antaretie Siple Coast produces areas at the pressure-melting point separated by strips of frozen-to-bed ice, the structure of which is reminiscent of Ice Streams A–E. This configuration appears to be robust, preserving its features in spite of climatic changes during the last glacial cycle. Ice Stream C seems to be more vulnerable to stagnation, switching to a passive mode at least once during the penultimate interglacial. We conjecture that the peculiarities of local topography determine the unique behavior of Ice Stream C: reduced basal stress and, consequently, relatively weak warming due to internal friction and basal sliding is not able to counteract the advective cooling during the periods of increased snowfall rate.

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Asynchronous instability of NE ice streams of the Laurentide Ice Sheet recorded in the marine sediments of Labrador Sea during the last glacial cycle

10.5194/egusphere-egu2020-6774 ◽

2020 ◽

Author(s):

Harunur Rashid ◽

Mary Smith ◽

Min Zeng ◽

Yang Wang ◽

Julie Drapeau ◽

...

Keyword(s):

Ice Sheet ◽

Laurentide Ice Sheet ◽

Labrador Sea ◽

Glacial Cycle ◽

Ice Streams ◽

Last Glacial ◽

Ice Stream ◽

Cumberland Sound ◽

Detrital Carbonate ◽

The Last Glacial

<p>Hughes et al. (1977) hypothesized of a pan-Arctic Ice Sheet that behaved as a single dynamic system during the Last Glacial Maximum. Moreover, the authors suggested a nearly grounded ice shelf in Davis Strait implying that little or no exchange between Baffin Island and the Labrador Sea. Here we present data at 1-cm (<100 years) resolution between ~12 ka and 45 ka that shed light on the discharge from Hudson Strait and Lancaster Sound ice streams of the Late Pleistocene Laurentide Ice Sheet. A reference sediment core at 938 m water depth on the SE Baffin Slope was investigated with new oxygen isotope stratigraphy, X-ray fluorescence geochemistry, and 18 14C-AMS dates and correlated to 14 regional deep-water cores. Detrital carbonate-rich sediment layers H0-H4 were derived principally from Hudson Strait. Shortly after H2 and H3, the shelf-crossing Cumberland Sound ice stream supplied dark brown ice-proximal stratified sediments but no glacigenic debris-flow deposits. The counterparts of H3, H4, and (?)H5 events in the deep Labrador basin are 4&#8211;10 m thick units of thin-bedded carbonate-rich mud turbidites from glacigenic debris flows on the Hudson Strait slope. The behavior of the Hudson Strait ice stream changed through the last glacial cycle. The Hudson Strait ice stream remained at the shelf break in H3-H5 but retreated rapidly across the shelf in H0-H2 and did not deglaciate Hudson Bay. During this time, Cumberland Sound ice twice reached the shelf edge. In H3&#8211;H5, it remained at the shelf break long enough to supply thick turbidites. Minor supply of carbonate-rich sediment from Baffin Bay allows chronologic integration of the Baffin Bay and Labrador Sea detrital carbonate records, which is diachronous with respect to Heinrich events. The asynchrony of the carbonate events implies an open seaway through Davis Strait. Our data suggest that the maximum extent of ice streams in Hudson Strait, Cumberland Sound, and Lancaster Sound was neither synchronous.</p>

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The deglaciation of coastal areas of southeast Greenland

The Holocene ◽

10.1177/0959683618777067 ◽

2018 ◽

Vol 28 (9) ◽

pp. 1535-1544 ◽

Cited By ~ 3

Author(s):

Laurence M Dyke ◽

Anna LC Hughes ◽

Camilla S Andresen ◽

Tavi Murray ◽

John F Hiemstra ◽

...

Keyword(s):

Ice Sheet ◽

Younger Dryas ◽

Greenland Ice Sheet ◽

Coastal Areas ◽

Glacial Cycle ◽

Last Glacial ◽

The North ◽

Exposure Ages ◽

The Last Glacial Maximum ◽

The Last Glacial

Large marine-terminating glaciers around the margins of the Greenland Ice Sheet have retreated, accelerated and thinned over the last two decades. Relatively little is known about the longer term behaviour of the Greenland Ice Sheet, yet this information is valuable for assessing the significance of modern changes. We address this by reporting 11 new beryllium-10 (10Be) exposure ages from previously uninvestigated coastal areas across southeast Greenland. The new ages are combined with existing data from the region to assess the timing of glacier retreat after the Last Glacial Maximum. The results show that deglaciation occurred first in the north of the region (~68°N) and progressed southwards. This north–south progression is attributed to the influence of the warm Irminger Current on the ice margin. Areas in the south of the region were isolated from the warm waters by the shallow bathymetry of the continental shelf. This demonstrates that oceanographic forcing paced the deglaciation of southeast Greenland through the Younger Dryas and early Holocene. In most areas of southeast Greenland bedrock ages are systematically older than their counterpart boulder samples; this offset is likely the result of inherited 10Be content in bedrock surfaces. This suggests that subglacial erosion during the last glacial cycle was insufficient to completely remove pre-existing 10Be content. Alternatively, this pattern may be the signature of a substantial retreat and advance cycle prior to final Holocene deglaciation.

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Modeling the Antarctic ice sheet

Annals of Glaciology ◽

10.3189/s0260305500014130 ◽

1997 ◽

Vol 25 ◽

pp. 259-268 ◽

Cited By ~ 4

Author(s):

Mikhail Verbitsky ◽

Barry Saltzman

Keyword(s):

Three Dimensional ◽

Ice Sheet ◽

Glacial Cycle ◽

Antarctic Ice Sheet ◽

Thermodynamic Equation ◽

Last Glacial ◽

West Antarctic ◽

Ice Stream ◽

The Antarctic ◽

The Last Glacial

A three-dimensional (3-D), high-resolution, non-linearly viscous, non-isothermal ice-sheet model is employed to calculate the “present-day” equilibrium regime of the Antarctic ice sheet and its evolution during the last glacial cycle. The model is augmented by an approximate formula for ice-sheet basal temperature, based on a scaling of the thermodynamic equation for the ice flow. Steady-state solutions for both the shape and extent of the areas of basal melting (or freezing) are shown to be in good agreement with those obtained from the solution of the full 3-D thermodynamic equation. The solution for the basal temperature field of the West Antarctic Siple Coast produces areas at the pressure-melting point separated by strips of frozen-to-bed ice, the structure of which is reminiscent of Ice Streams A–E. This configuration appears to be robust, preserving its features in spite of climatic changes during the last glacial cycle. Ice Stream C seems to be more vulnerable to stagnation, switching to a passive mode at least once during the penultimate interglacial. We conjecture that the peculiarities of local topography determine the unique behavior of Ice Stream C: reduced basal stress and, consequently, relatively weak warming due to internal friction and basal sliding is not able to counteract the advective cooling during the periods of increased snowfall rate.

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Modeling Northern Hemispheric ice sheet dynamics, sea level change and solid Earth deformation through the last glacial cycle

Journal of Geophysical Research Earth Surface ◽

10.1029/2020jf006040 ◽

2021 ◽

Author(s):

Holly Kyeore Han ◽

Natalya Gomez ◽

David Pollard ◽

Robert DeConto

Keyword(s):

Solid Earth ◽

Sea Level ◽

Ice Sheet ◽

Sea Level Change ◽

Glacial Cycle ◽

Last Glacial ◽

Level Change ◽

Northern Hemispheric ◽

Ice Sheet Dynamics ◽

The Last Glacial

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Southwest Greenland shelf glaciation during MIS 4 more extensive than during the Last Glacial Maximum

Scientific Reports ◽

10.1038/s41598-019-51983-3 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Marit-Solveig Seidenkrantz ◽

Antoon Kuijpers ◽

Jesper Olsen ◽

Christof Pearce ◽

Sofia Lindblom ◽

...

Keyword(s):

Sea Water ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Glacial Cycle ◽

Oxygen Isotope Stage ◽

Last Glacial ◽

Irminger Sea ◽

West Greenland Current ◽

Glacial Advance ◽

The Last Glacial

Abstract Although geological and modelling evidence indicate that the last glacial inception in North America was in NE Canada, little is known about the glacial response of the nearby western Greenland Ice Sheet (GIS) during the glacial advance of marine oxygen isotope stage 4 (MIS4). Our multi-proxy study of a marine sediment core collected about 60 km southwest of the Outer Hellefisk Moraines demonstrates that in the southern Davis Strait region the most extreme Greenland shelf glaciation of the last glacial cycle occurred during MIS 4, with another prominent glacial advance at 37–33 kyr BP. During those periods the GIS likely reached the Outer Hellefisk Moraines in this area. Except for these two periods, our data suggest significant advection of relatively warm Irminger Sea Water by the West Greenland Current since MIS 4. This advection likely limited the extent of the MIS2 glaciation on the SW Greenland shelf. Decreased precipitation over southwestern Greenland predicted by atmospheric models as a downstream effect of a much larger MIS2 Laurentide Ice Sheet may have played an additional role.

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Last Glacial ice-sheet dynamics offshore NE Greenland – a case study from Store Koldewey Trough

10.5194/tc-2019-281 ◽

2020 ◽

Author(s):

Ingrid Leirvik Olsen ◽

Matthias Forwick ◽

Jan Sverre Laberg ◽

Tom Arne Rydningen ◽

Katrine Husum

Keyword(s):

Ice Sheet ◽

Outer Part ◽

Greenland Ice Sheet ◽

Middle Part ◽

Ice Streams ◽

Last Glacial ◽

Swath Bathymetry ◽

Ice Stream ◽

Ice Sheet Dynamics ◽

Greenland Margin

Abstract. New swath bathymetry and high-resolution seismic data, supplemented with multi-proxy analyses of sediment gravity cores from Store Koldewey Trough, NE Greenland, support the presence of a shelf-break terminating Greenland Ice Sheet (GIS) on the northeastern part of the Greenland Margin during the Last Glacial Maximum (LGM). The presence of mega-scale glacial lineations and a grounding zone wedge in the outer part of the trough provides evidence of the expansion of fast-flowing, grounded ice, probably originating from the area presently covered with the Storstrømmen ice stream and cutting across Store Koldewey Island and Germania Land. Multiple halts and/or readvances interrupted the deglaciation. Two sets of crevasse-squeezed ridges in the outer and middle part of the trough may indicate repeated surging of the GIS during the deglaciation. The complex landform assemblage in Store Koldewey Trough is suggested to reflect a relatively slow and stepwise retreat during the deglaciation. Thus, the ice retreat probably occurred asynchronously relative to other ice streams offshore NE Greenland. Subglacial till fills the trough, with an overlying thin drape of maximum 2.5 m thickness of glacier proximal and glacier distal sediment. At a late stage of the deglaciation, the ice stream retreated across Store Koldewey Island and Germania Land, terminating the sediment input from this sector of the GIS to Store Koldewey Trough.

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