New results on the dynamics of the NW part of the Svalbard Ice Sheet during the deglaciation of the Woodfjorden Trough

2020 ◽  
Author(s):  
Tom Arne Rydningen ◽  
Amando Lasabuda ◽  
Jan Sverre Laberg ◽  
Christine Tømmervik Kollsgård ◽  
Stine Bjordal Olsen ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Ice Sheet ◽  
Outer Part ◽  
Middle Part ◽  
The Arctic ◽  
Quality Data ◽  
Glacier Front ◽  
Ice Retreat ◽  
Late Weichselian ◽  
Glacial Landforms

<p>Present-day warming is most pronounced at high latitudes, raising concern for the stability of modern ice caps such as the ones overlying the Svalbard archipelago. Palaeo-records give us opportunity to understand past behavior of these systems, including the ice retreat from the continental shelf at the end of the last glaciation. In order to evaluate and reconstruct this in a robust way, it is essential that we acquire high-quality data sets covering key areas in the Arctic.</p><p>New multi-beam bathymetric data was acquired in July 2019 from the Woodfjorden Trough; an up to 60 km long and 40 km wide transverse trough on the northwestern part of the Svalbard continental shelf. Previous investigations have shown that this trough was occupied by a major ice stream draining the Svalbard Ice Sheet during the last glacial, but the deglacial dynamics of this sector of the Svalbard Ice Sheet are presently not well constrained.</p><p>The new data reveal a complex seabed morphology including larger (2 km wide, 50 m high) and smaller (100 m wide, 3 m high) ridges, as well as sediment wedges (1 to 2 km wide, 30 m high), partly showing crosscutting relationships. These ridges and wedges are discontinuous in the outer part of the trough, where they are partly superposed by glacial lineations and small- to larger sized iceberg ploughmarks (up to 1500 m wide and 30 m deep). In the middle part of the trough, more continuous ridges dominate.</p><p>The ridges and wedges are interpreted to be glacial landforms formed by grounded ice within the Woodfjorden Trough. Their crosscutting relationships testify to a complex deglaciation, including several advances and still stands of the ice front during overall ice retreat, and their size could indicate that the glacier front was stable for some time. Smaller ridges may be retreat moraines formed during shorter (annual?) still stands of the glacier front. Based on their discontinuous characteristics, the ridges and wedges in the outer part of the trough may pre-date the final Late Weichselian deglaciation, i.e. they may have been overridden by a grounded glacier. The more continuous character of the ridges in the middle part of the trough indicate that these likely date from the Late Weichselian deglaciation.</p><p>The glacial landforms identified here are rather atypical for glacial troughs, commonly dominated by mega-scale glacial lineations superposed by one or a few grounding zone wedges and/or smaller retreat moraines. The abundant morainal systems and glacial lineations of the Woodfjorden Trough, instead, testify to highly dynamic grounded ice occupying the trough, and a retreat which was characterized by several periods of ice margin stability, interrupted by readvances. This fits with recent studies from onshore areas, showing that the deglaciation of northern Svalbard was at least partly characterized by glacial readvances during the overall ice retreat.</p>

Late Weichselian Ice Sheet of Northern Eurasia

1980 ◽  
Vol 13 (1) ◽  
pp. 1-32 ◽  
Author(s):  
M. G. Grosswald
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Ice Sheet ◽  
West Siberia ◽  
The Arctic ◽  
Russian Plain ◽  
Northern Eurasia ◽  
Taimyr Peninsula ◽  
Continental Shelves ◽  
Late Weichselian

AbstractA considerable portion of Northern Eurasia, and particularly its continental shelf, was glaciated by inland ice during late Weichsel time. This was first inferred from such evidence as glacial striae, submarine troughs, sea-bed diamictons, boulder trains on adjacent land, and patterns of glacioisostatic crustal movements. Subsequently, the inference was confirmed by data on the occurrence and geographic position of late Weichselian end moraines and proglacial lacustrine deposits.The south-facing outer moraines in the northeastern Russian Plain, northern West Siberia, and on Taimyr Peninsula are underlain by sediments containing wood and peat, the radiocarbon dating of which yielded ages of 22,000 to 45,000 yr B.P. The youngest late-glacial moraines are of Holocene age: the double Markhida moraine in the lower Pechora River basin, presumably associated with “degradational” surges of the Barents Ice Dome, is underlain by sediments with wood and peat dated at 9000 to 9900 yr B.P.: this suggests that deglaciation of the Arctic continental shelf of Eurasia was not completed until after 9000 yr B.P.The reconstructed ice-front lines lead to the conclusion that the late Weichselian ice sheet of Northern Eurasia (proposed name: theEurasian Ice Sheet) extended without interruptions from southwestern Ireland to the northeastern end of Taimyr Peninsula, a distance of 6000 km: it covered an area of 8,370,000 km2, half of which lay on the present-day continental shelves and a quarter on lowlands that were depressed isostatically below sea level. Hence, the ice sheet was predominantly marine-based.A contour map of the ice sheet based both on the dependence of the heights of ice domes upon their radii and on factual data concerning the impact of bedrock topography upon ice relief has been constructed. The major features of the ice sheet were the British, Scandinavian, Barents, and Kara Ice Domes that had altitudes of 1.9 to 3.3 km and were separated from one another by ice saddles about 1.5 km high. At the late Weichselian glacial maximum, all the main ice-dispersion centers were on continental shelves and coastal lowlands, whereas mountain centers, such as the Polar Urals and Byrranga Range, played only a local role.The portions of the ice sheet that were grounded on continental shelves some 700 to 900 m below sea level were inherently unstable and could exist only in conjunction with confined and pinned floating ice shelves that covered the Arctic Ocean and the Greenland and Norwegian Seas.The Eurasian Ice Sheet impounded the Severnaya Dvina, Mezen, Pechora, Ob, Irtysh, and Yneisei Rivers, and caused the formation of ice-dammed lakes on the northern Russian Plain and in West Siberia. Until about 13,500 yr B.P. the proglacial system of lakes and spillways had a radial pattern; it included large West Siberian lakes, the Caspian and Black Seas, and ended in the Mediterranian Sea. Later, the system became marginal and discharged proglacial water mainly into the Norwegian Sea.

scholarly journals A global high-resolution data set of ice sheet topography, cavity geometry and ocean bathymetry

2016 ◽  
Author(s):  
Janin Schaffer ◽  
Ralph Timmermann ◽  
Jan Erik Arndt ◽  
Steen Savstrup Kristensen ◽  
Christoph Mayer ◽  
...  
Keyword(s):  
High Resolution ◽  
Continental Shelf ◽  
Ice Sheet ◽  
The Arctic ◽  
Global Ocean ◽  
Data Set ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Surface Topographies ◽  
The Antarctic

Abstract. The ocean plays an important role in modulating the mass balance of the polar ice sheets by interacting with the ice shelves in Antarctica and with the marine-terminating outlet glaciers in Greenland. Given that the flux of warm water onto the continental shelf and into the sub-ice cavities is steered by complex bathymetry, a detailed topography data set is an essential ingredient for models that address ice-ocean interaction. We followed the spirit of the global RTopo-1 data set and compiled consistent maps of global ocean bathymetry, upper and lower ice surface topographies and global surface height on a spherical grid with now 30-arc seconds resolution. We used the General Bathymetric Chart of the Oceans (GEBCO_2014) as the backbone and added the International Bathymetric Chart of the Arctic Ocean version 3 (IBCAOv3) and the International Bathymetric Chart of the Southern Ocean (IBCSO) version 1. While RTopo-1 primarily aimed at a good and consistent representation of the Antarctic ice sheet, ice shelves and sub-ice cavities, RTopo-2 now also contains ice topographies of the Greenland ice sheet and outlet glaciers. In particular, we aimed at a good representation of the fjord and shelf bathymetry surrounding the Greenland continent. We corrected data from earlier gridded products in the areas of Petermann Glacier, Hagen Bræ and Sermilik Fjord assuming that sub-ice and fjord bathymetries roughly follow plausible Last Glacial Maximum ice flow patterns. For the continental shelf off northeast Greenland and the floating ice tongue of Nioghalvfjerdsfjorden Glacier at about 79° N, we incorporated a high-resolution digital bathymetry model considering original multibeam survey data for the region. Radar data for surface topographies of the floating ice tongues of Nioghalvfjerdsfjorden Glacier and Zachariæ Isstrøm have been obtained from the data centers of Technical University of Denmark (DTU), Operation Icebridge (NASA/NSF) and Alfred Wegener Institute (AWI). For the Antarctic ice sheet/ice shelves, RTopo-2 largely relies on the Bedmap-2 product but applies corrections for the geometry of Getz, Abbot and Fimbul ice shelf cavities. The data set is available in full and in regional subsets in NetCDF format from the PANGAEA database at https://doi.pangaea.de/10.1594/PANGAEA.856844.

The Glacial History of the Svalberd Archipelago from Late Vistulian to the Present Time / Historia zlodowacenia archipelagu Svalbard od późnego vistulianu do współczesności

2014 ◽  
Vol 69 (2) ◽  
Author(s):  
Joanna Ćwiąkała ◽  
Mateusz Moskalik ◽  
Jan Rodzik ◽  
Piotr Zagórski
Keyword(s):  
Continental Shelf ◽  
20Th Century ◽  
Ice Sheet ◽  
Ice Age ◽  
The Arctic ◽  
Glacial History ◽  
Svalbard Archipelago ◽  
Maximum Extent ◽  
Late Vistulian ◽  
History Of

AbstractThe glacial history of the Svalbard archipelago is often a hot topic for researches, but the articles usually refer to a particular piece of Svalbard. The authors of this work studied many scientific articles based on the researches to find and collect this history. Svalbard archipelago is located in the Arctic, at the edge of the continental shelf of Europe. The end of shelf boundary noted occurrence of ice caps in the past glaciations. In turn, the main elements of the landscape of the archipelago are glaciers that are currently in a recession. Spitsbergen (the biggest island of the archipelago) sets the limit of Pleistocene glaciations, and the current state of glaciers allows determining the place where the recession is intense. The main aim of the authors in this study is to show this history only from the late Vistulian to the late Holocene (the beginning of 21st century). Interstadials and Stadials start time varies, as their duration in different places, according to various authors. It is very hard to collect all information and describe this history. By knowing the history of glaciation, we can distinguish in the late Vistulian: Last Glacial Maximum (LGM), Bølling/Older Dryas/Allerød and Younger Dryas (YD). LGM was the stadial in which was the maximum extent of ice sheet in late Vistulian. After this period, ice sheet began to retreat from the continental shelf. In turn, YD was the stadial in which the last advance of glaciers took place, about 11 000 years BC. In the Holocene we can distinguish Holocene Climatic Optimum (in the meantime short Cooling Holocene), Revdalen Stadial, Medieval Warm Period, Little Ice Age (LIA) and 20th century warming. The maximum extent of glaciers in Holocene was in LIA. In LIA, the extent of glaciers was bigger than in YD. In 20th century a warming started and continues until now.

scholarly journals Asymmetric ice-sheet retreat pattern around northern Scotland revealed by marine geophysical surveys

2014 ◽  
Vol 105 (4) ◽  
pp. 297-322 ◽  
Author(s):  
Tom Bradwell ◽  
Martyn Stoker
Keyword(s):  
Continental Shelf ◽  
Ice Sheet ◽  
Large Area ◽  
Ice Dynamics ◽  
Single Beam ◽  
Orkney Islands ◽  
Bed Topography ◽  
Geophysical Surveys ◽  
Geological Information ◽  
Late Weichselian

ABSTRACTThis study uses marine geophysical data, principally single-beam and high-resolution multibeam echo sounder bathymetry, combined with seismic sub-bottom profiles, and existing Quaternary geological information, to map the glacial geomorphology of a large area of seafloor (∼50,000 km2) on the continental shelf around northern Scotland, from west of Lewis to north of the Orkney Islands. Our new mapping reveals the detailed pattern of submarine glacial landforms, predominantly moraines, relating to ice sheets that covered Scotland and much of the continental shelf during the Late Weichselian glaciation and earlier in the Mid to Late Pleistocene. The reconstructed retreat pattern based on geomorphological evidence highlights the large number of different retreat stages and the asymmetric, non-uniform evolution of this ice sheet sector during Late Weichselian deglaciation. Time-equivalent ice-front reconstructions show that marine sectors of the ice sheet, such as the Minch, changed their geometry significantly, perhaps rapidly; whilst other sectors remained relatively unchanged and stable. We suggest that this behaviour, governed principally by bed topography/bathymetry and ice dynamics, led to reorganisation of the Late Weichselian ice sheet as it retreated back to two main ice centres: one in Western Scotland and the other over Orkney and Shetland. This retreat pattern suggests relatively early deglaciation of NW Lewis (ca. 25 ka BP) and the mountains of far NW Scotland – the latter possibly forming a substantial ice-free land corridor. Our reconstructions differ from most previous syntheses, but are strongly supported by the independently-mapped offshore Quaternary succession and key onshore dating constraints.

scholarly journals The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin

2017 ◽  
Vol 13 (9) ◽  
pp. 1269-1284 ◽  
Author(s):  
Matt O'Regan ◽  
Jan Backman ◽  
Natalia Barrientos ◽  
Thomas M. Cronin ◽  
Laura Gemery ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Arctic Ocean ◽  
Ice Sheets ◽  
Laminated Sediments ◽  
The Arctic ◽  
Outer Continental Shelf ◽  
Last Glacial ◽  
Glacial Landforms ◽  
Siberian Shelf ◽  
The Last Glacial

Abstract. Ice sheets extending over parts of the East Siberian continental shelf have been proposed for the last glacial period and during the larger Pleistocene glaciations. The sparse data available over this sector of the Arctic Ocean have left the timing, extent and even existence of these ice sheets largely unresolved. Here we present new geophysical mapping and sediment coring data from the East Siberian shelf and slope collected during the 2014 SWERUS-C3 expedition (SWERUS-C3: Swedish – Russian – US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions). The multibeam bathymetry and chirp sub-bottom profiles reveal a set of glacial landforms that include grounding zone formations along the outer continental shelf, seaward of which lies a  >  65 m thick sequence of glacio-genic debris flows. The glacial landforms are interpreted to lie at the seaward end of a glacial trough – the first to be reported on the East Siberian margin, here referred to as the De Long Trough because of its location due north of the De Long Islands. Stratigraphy and dating of sediment cores show that a drape of acoustically laminated sediments covering the glacial deposits is older than ∼ 50 cal kyr BP. This provides direct evidence for extensive glacial activity on the Siberian shelf that predates the Last Glacial Maximum and most likely occurred during the Saalian (Marine Isotope Stage (MIS) 6).

Oriented lake-and-ridge assemblages of the Arctic coastal plains: glacial landforms modified by thermokarst and solifluction

Polar Record ◽  
1999 ◽  
Vol 35 (194) ◽  
pp. 215-230 ◽  
Author(s):  
Mikhail G. Grosswald ◽  
Terence J. Hughes ◽  
Norman P. Lasca
Keyword(s):  
Ice Sheet ◽  
Late Glacial ◽  
The Arctic ◽  
Laurentide Ice Sheet ◽  
Baffin Island ◽  
Mackenzie Delta ◽  
Space Images ◽  
The North ◽  
Arctic Ice ◽  
Glacial Landforms

AbstractOriented assemblages of parallel ridges and elongated lakes are widespread on the coastal lowlands of northeast Eurasia and Arctic North America, in particular, in Alaska, Arctic Canada, and northeast Siberia. So far, only the oriented lakes have been of much scientific interest. They are believed to be formed by thermokarst in perennially frozen ice-rich sediments, while their orientation is accounted for either by impact of modern winds blowing at right angles to long axes of the lakes (when it concerns individual lakes), or by the influence of underlying bedrock structures (in the case of longitudinal and transverse alignment of lake clusters).En masseexamination of space images suggests that oriented lake-and-ridge assemblages, not the oriented lakes alone, occur in the Arctic. Hence any theory about their formation should account for the origin and orientation of the assemblages as a whole. The existing hypotheses appear inadequate for this end, so this paper proposes that the assemblages were initially created by glacial activity, that is, by ice sheets that drumlinized and tectonized their beds, as well as by sub- and proglacial meltwater, and then they were modified by thermokarst, solifluction, and aeolian processes. This assumption opens up an avenue by which all known features of oriented landforms in the Arctic can be explained. The paper suggests that the oriented landforms in Siberia and Alaska are largely signatures of a marine Arctic ice sheet that transgressed from the north, while the Baffin Island and Mackenzie Delta forms were created by the respective sectors of the Laurentide ice sheet. The oriented features discussed belong to the last Late Glacial through the Early Holocene.

scholarly journals A global, high-resolution data set of ice sheet topography, cavity geometry, and ocean bathymetry

2016 ◽  
Vol 8 (2) ◽  
pp. 543-557 ◽  
Author(s):  
Janin Schaffer ◽  
Ralph Timmermann ◽  
Jan Erik Arndt ◽  
Steen Savstrup Kristensen ◽  
Christoph Mayer ◽  
...  
Keyword(s):  
High Resolution ◽  
Continental Shelf ◽  
Ice Sheet ◽  
The Arctic ◽  
Global Ocean ◽  
Data Set ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Surface Topographies ◽  
The Antarctic

Abstract. The ocean plays an important role in modulating the mass balance of the polar ice sheets by interacting with the ice shelves in Antarctica and with the marine-terminating outlet glaciers in Greenland. Given that the flux of warm water onto the continental shelf and into the sub-ice cavities is steered by complex bathymetry, a detailed topography data set is an essential ingredient for models that address ice–ocean interaction. We followed the spirit of the global RTopo-1 data set and compiled consistent maps of global ocean bathymetry, upper and lower ice surface topographies, and global surface height on a spherical grid with now 30 arcsec grid spacing. For this new data set, called RTopo-2, we used the General Bathymetric Chart of the Oceans (GEBCO_2014) as the backbone and added the International Bathymetric Chart of the Arctic Ocean version 3 (IBCAOv3) and the International Bathymetric Chart of the Southern Ocean (IBCSO) version 1. While RTopo-1 primarily aimed at a good and consistent representation of the Antarctic ice sheet, ice shelves, and sub-ice cavities, RTopo-2 now also contains ice topographies of the Greenland ice sheet and outlet glaciers. In particular, we aimed at a good representation of the fjord and shelf bathymetry surrounding the Greenland continent. We modified data from earlier gridded products in the areas of Petermann Glacier, Hagen Bræ, and Sermilik Fjord, assuming that sub-ice and fjord bathymetries roughly follow plausible Last Glacial Maximum ice flow patterns. For the continental shelf off Northeast Greenland and the floating ice tongue of Nioghalvfjerdsfjorden Glacier at about 79° N, we incorporated a high-resolution digital bathymetry model considering original multibeam survey data for the region. Radar data for surface topographies of the floating ice tongues of Nioghalvfjerdsfjorden Glacier and Zachariæ Isstrøm have been obtained from the data centres of Technical University of Denmark (DTU), Operation Icebridge (NASA/NSF), and Alfred Wegener Institute (AWI). For the Antarctic ice sheet/ice shelves, RTopo-2 largely relies on the Bedmap-2 product but applies corrections for the geometry of Getz, Abbot, and Fimbul ice shelf cavities. The data set is available in full and in regional subsets in NetCDF format from the PANGAEA database at doi:10.1594/PANGAEA.856844.

A LiDAR-based glacial landform map of the Kebnekaise massif, northern Sweden

2020 ◽  
Author(s):  
Calum Edward ◽  
Robin Blomdin ◽  
Gunhild Rosqvist
Keyword(s):  
Global Climate ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Aerial Photographs ◽  
Terrain Model ◽  
Scandinavian Ice Sheet ◽  
The Face ◽  
Ice Retreat ◽  
Ground Truthing ◽  
Glacial Landforms

<p>In the face of global climate change, and the associated melting of the modern-day ice sheets, the understanding and reconstruction of the dynamics and retreats of former ice sheets has become an increasingly valuable tool and indicator of the future behaviour of present-day ice masses. The deglacial period that followed the Last Glacial Maximum (~22-9 thousand years ago) represents the most recent major warming event, and final ice sheet decay, in Earth history, and is an important analogue for the threat of present-day ice sheet collapse. The recent availability of the 2m-resolution Swedish LiDAR based terrain model provides the opportunity to map glacial landforms and landscapes over large areas with greater accuracy than was previously possible through satellite images or aerial photographs. In combination with field observation-based ground-truthing, this LiDAR resource is employed to map the geomorphology of the Kebnekaise region of the northern Swedish mountains with the principal aim of producing a landform-driven reconstruction of the deglaciation of the remnant Scandinavian Ice Sheet during its final stage of retreat. The complex ‘palimpsest’ landscape is delineated and interpreted through the classification of landforms according to their relative age and respective origin. In particular, attention will be given to the segregation of glacial (e.g., terminal moraines, lineations), deglacial (e.g., eskers, lateral meltwater channels, glacial lake shorelines) and ‘relict’ (i.e., pre-glacial palaeosurfaces) landform assemblages, in order to demarcate those formed during the final deglaciation.   The resulting landform selections are used to delineate high-resolution ice retreat patterns, giving indication to the nature of the basal thermal regime, topographic response and final remnant location of the ice sheet. Additionally, this assay serves as an evaluation of the use of the Swedish LiDAR database as a means of efficiently and accurately mapping previously-glaciated landscapes. Our deglaciation reconstruction will finally be tested against formerly produced regional reconstructions.</p>

The Last Glaciation and Geomorphology

2005 ◽  
Author(s):  
Margot Böse
Keyword(s):  
Boreal Forests ◽  
Ice Sheet ◽  
Drainage System ◽  
Middle Part ◽  
Middle Pleistocene ◽  
Last Interglacial ◽  
The North ◽  
Last Glaciation ◽  
The North Sea ◽  
Late Weichselian

The Weichselian ice sheets were smaller than those of the preceding Middle Pleistocene and covered only the north-eastern part of the German lowland, as well as the eastern and northern parts of the Jutland peninsula. The Late Weichselian (Late Devensian) ice sheet also covered the northern part of the North Sea Basin (Ehlers and Wingfield 1991). The young morainic landscape still has distinct morphological features distinguishing it from the old morainic areas with relief shaped by the long-lasting periglacial processes during the Weichselian. The area of the last glaciation is easily recognizable on topographical maps owing to the irregular relief and the numerous lakes that are still preserved today. This scenic landscape also features end moraines and kames, till plains, and huge meltwater valleys (pradolinas or Urstromtäler), as well as a complex drainage system. The general climatic development of the last interglacial- glacial-Holocene cycle can be interpreted from curves showing the ratio of the oxygen isotopes 18O and 16O in deep-sea sediments, which is indirectly indicative of the growth of ice masses worldwide. The different OIS (Oxygen Isotope Stages) are numbered, with uneven numbers representing the relatively warmer phases. OIS 5e corresponds to the Eemian Interglacial. The stages 5d–5a represent the Early Weichselian, which is colder than the preceding interglacial but is subdivided into stadials and interstadials. The Brørup interstadial s.l., including both the Amersfoort (5c) and the Odderade interstadial (5a), is characterized by boreal forests in this part of Europe. OIS 4 marks the onset of the Middle Weichselian or Pleniglacial, and is the first stage involving much lower temperatures and the growth of considerable ice masses. This is probably the time when a real inland ice sheet started to grow in Fennoscandia. OIS 3, the middle part of the Pleniglacial, is represented by several climatic changes. The interstadials—or intervals, as they are also called—such as Oerel, Glinde, Moershoofd, Hengelo, and Denekamp—are well documented by terrestrial palynological records of a herb and shrub bush vegetation (van der Hammen et al. 1967; Behre 1989; Caspers and Freund 2001).

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

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.

Sign in / Sign up

Export Citation Format

Share Document