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Jan Mangerud - One of the best experts on this subject based on the ideXlab platform.
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Tracing the last remnants of the Scandinavian Ice Sheet: Ice-dammed lakes and a catastrophic outburst flood in northern Sweden
Quaternary Science Reviews, 2019Co-Authors: Carl Regnéll, Jan Mangerud, John Inge SvendsenAbstract:Abstract We present geomorphological evidence of large, previously undocumented, early Holocene Ice-dammed lakes in the Scandinavian Mountains of northwestern Sweden. The lakes extents indicate that the last remnants of the Scandinavian Ice Sheet were located east of the mountain range. Some early pioneering works have presented similar reconstructions, whereas more recently published reconstructions place the last Ice remnants in the high mountains of Sarek. Using high-resolution airborne LiDAR data we have mapped a large number of hitherto undocumented shorelines in some of the main valleys within the northern Scandinavian mountain range. Our results indicate that a larger system of Ice-dammed lakes existed in this region than previously thought. The lakes were dammed between the main water divide to the west and the retreating Ice Sheet margin to the east. The shorelines dip towards the northwest with gradients ranging from 0.5 to 0.4 m/km, from the oldest to the youngest. Further, we have compiled Lateglacial and Holocene shoreline data along the Norwegian coast and from within the Baltic Sea basin and reconstructed the isostatic uplift along a 1400 km long northwest-southeast transect from the Norwegian Sea to Lake Ladoga. By comparing the measured Ice-dammed lake shoreline gradients to the dated marine shorelines, we infer that the lakes may have existed for several centuries following 10.2 cal ka BP. We also describe large deposits and extensive erosive features, which demonstrate that a catastrophic glacial lake outburst flood (GLOF) took place eastward along the Pite River Valley. Based on cross-cutting relations to raised shorelines developed in the early Holocene Ancylus Lake (Baltic Sea basin) we conclude that the flood and thus the final phase of deglaciation took place within the time interval 10.3–9.9 cal ka BP.
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Atmosphere-driven Ice Sheet mass loss paced by topography: Insights from modelling the south-western Scandinavian Ice Sheet
Quaternary Science Reviews, 2018Co-Authors: Henning Åkesson, John Inge Svendsen, Mathieu Morlighem, Kerim H. Nisancioglu, Jan MangerudAbstract:Abstract Marine-terminating glaciers and Ice streams are important controls of Ice Sheet mass balance. However, understanding of their long-term response to external forcing is limited by relatively short observational records of present-day glaciers and sparse geologic evidence for paleo-glaciers. Here we use a high-resolution Ice Sheet model with an accurate representation of grounding line dynamics to study the deglaciation of the marine-based south-western Norwegian sector of the Scandinavian Ice Sheet and its sensitivity to ocean and atmosphere forcing. We find that the regional response to a uniform climate change is highly dependent on the local bedrock topography, consistent with Ice Sheet reconstructions. Our simulations suggest that ocean warming is able to trigger initial retreat in several fjords, but is not sufficient to explain retreat everywhere. Widespread retreat requires additional Ice thinning driven by surface melt. Once retreat is triggered, the underlying bedrock topography and fjord width control the rate and extent of retreat, while multi-millennial changes over the course of deglaciation are modulated by surface melt. We suggest that fjord geometry, Ice-ocean interactions and grounding line dynamics are vital controls of decadal-to centennial scale Ice Sheet mass loss. However, we postulate that atmospheric changes are the most important drivers of widespread Ice Sheet demise, and will likely trump oceanic influence on future Ice Sheet mass loss and resulting sea level rise over centennial and longer time scales.
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A major re-growth of the Scandinavian Ice Sheet in western Norway during Allerød-Younger Dryas
Quaternary Science Reviews, 2016Co-Authors: Jan Mangerud, Inge Aarseth, Anna L.c. Hughes, Øystein S. Lohne, Kåre Skår, Eivind Sønstegaard, John Inge SvendsenAbstract:Abstract Distinct Younger Dryas (YD) moraines are mapped more-or-less continuously around the Scandinavian Ice Sheet. In most areas there is no evidence to suggest that a glacial re-advance took place during the YD, either because it did not happen or because older deposits have been removed by glacial erosion. In contrast we here present 90 radiocarbon dates from 36 different sites that were overrun by a major Ice Sheet advance in the area between Hardangerfjorden and Sognefjorden, SW Norway. Thus this region is exceptional for examining the glacial response to the climate shifts across Allerod-YD. The re-growth of the Ice Sheet in this sector commenced during the Allerod Interstadial. It expanded along 600–800 m deep fjords reaching a thickness of up to 2000 m. We produce time–distance diagrams for two lobes; for both the outermost coast became Ice free close to 15 cal ka BP, i.e. at the onset of the Bolling. The Hardangerfjorden Lobe re-advanced during the Older Dryas (14 cal ka BP), an event that was not replicated for the Herdla Lobe farther north. Both lobes reached their most landward position before re-advancing at 13.5–13.0 cal ka and obtained their maximum extent at the very end of the YD, 11.5 cal ka. The late culmination of the advance is accurately dated and differs from most of the Scandinavian Ice Sheet margin where the maximum was reached during early or middle YD. We also present a time–distance diagram from the Last Glacial Maximum to the Ice divide showing two-step retreat; fast retreat occurs 21–20 and 11.5–10 cal ka BP separated by a period of almost no net retreat 20–11.5 cal ka BP, which contrasts with much more even retreat in other parts of the Scandinavian Ice Sheet.
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Early break-up of the Norwegian Channel Ice Stream during the Last Glacial Maximum
Quaternary Science Reviews, 2015Co-Authors: John Inge Svendsen, Jan Mangerud, Jason P. Briner, Nicolás E. YoungAbstract:10Be dating Last Glacial Maximum abstract We present 18 new cosmogenic 10 Be exposure ages that constrain the breakup time of the Norwegian Channel Ice Stream (NCIS) and the initial retreat of the Scandinavian Ice Sheet from the Southwest coast of Norway following the Last Glacial Maximum (LGM). Seven samples from glacially transported erratics on the island Utsira, located in the path of the NCIS about 400 km up-flow from the LGM Ice front position, yielded an average 10 Be age of 22.0 ± 2.0 ka. The distribution of the ages is skewed with the 4 youngest all within the range 20.2e20.8 ka. We place most confidence on this cluster of ages to constrain the timing of Ice Sheet retreat as we suspect the 3 oldest ages have some inheritance from a previous Ice free period. Three additional ages from the adjacent island Karmoy provided an average age of 20.9 ± 0.7 ka, further supporting the new timing of retreat for the NCIS. The 10 Be ages from Utsira and Karmoy suggest that the Ice stream broke up about 2000 years earlier than the age assignment based on 14 C ages on foraminifera and molluscs from marine sediment cores. We postulate that the Scandinavian Ice Sheet flowed across the Norwegian Channel to Denmark and onto the North Sea plateau during early phases of the LGM. When the NCIS started to operate this Ice supply to the North Sea was cut off and the fast flow of the NCIS also led to a lowering of the Ice surface along the Norwegian Channel and thereby drawdown of the entire Ice Sheet. This facilitated rapid calving of the Ice front in the North Sea and we reconstruct a large open bay across the entire northern North Sea by ~20 ka based on our 10 Be ages in the
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A 10Be chronology of south‐western Scandinavian Ice Sheet history during the Lateglacial period
Journal of Quaternary Science, 2014Co-Authors: Jason P. Briner, Jan Mangerud, Øystein S. Lohne, John Inge Svendsen, Nicolás E. YoungAbstract:We present 34 new cosmogenic 10Be exposure ages that constrain the Lateglacial (Bolling–Preboreal) history of the Scandinavian Ice Sheet in the Lysefjorden region, south-western Norway. We find that the classical Lysefjorden moraines, earlier thought to be entirely of Younger Dryas age, encompass three adjacent moraines attributed to at least two Ice Sheet advances of distinctly different ages. The 10Be age of the outermost moraine (14.0 ± 0.6 ka; n = 4) suggests that the first advance is of Older Dryas age. The innermost moraine is at least 2000 years younger and was deposited near the end of the Younger Dryas (11.4 ± 0.4 ka; n = 7). After abandonment of the innermost Lysefjorden Moraine, the Ice front receded quickly towards the head of the fjord, where recession was interrupted by an advance that deposited the Trollgaren Moraine at 11.3 ± 0.9 ka (n = 5). 10Be ages from the inboard side of the Trollgaren Moraine suggest final retreat by 10.7 ± 0.3 ka (n = 7). The late culmination of the Younger Dryas advance contrasts with other sectors of the Scandinavian Ice Sheet where the margin appears to have culminated earlier during the Younger Dryas stadial, followed by retreat during the middle and late part of the Younger Dryas.
Eiliv Larsen - One of the best experts on this subject based on the ideXlab platform.
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14c dated fluctuations of the western flank of the Scandinavian Ice Sheet 45 25 kyr bp compared with bolling younger dryas fluctuations and dansgaard oeschger events in greenland
Boreas, 2010Co-Authors: Jan Mangerud, Steinar Gulliksen, Eiliv LarsenAbstract:Mangerud, J., Gulliksen, S. & Larsen, E. 2009: 14C-dated fluctuations of the western flank of the Scandinavian Ice Sheet 45–25 kyr BP compared with Bolling–Younger Dryas fluctuations and Dansgaard–Oeschger events in Greenland. Boreas, 10.1111/j.1502-3885.2009.00127.x. ISSN 0300-9483. We present 32 accelerator mass spectrometry (AMS) 14C dates obtained on well-preserved bones from caves in western Norway. The resulting ages of 34–28 14C kyr BP demonstrate that the coast was Ice-free during the so-called Alesund Interstadial. New AMS 14C dates on shells aged 41–38 14C kyr BP are evidence of an earlier (Austnes) Ice-free period. The Alesund Interstadial correlates with Greenland interstadials 8–7 and the Austnes Interstadial with Greenland interstadials 12–11. Between and after the two interstadials, the Ice margin reached onto the continental shelf west of Norway. These events can be closely correlated with the Greenland Ice core stratigraphy, partly based on identification of the Laschamp and Mono Lake palaeomagnetic excursions. We found that the pattern of the NGRIP δ18O curves for the two periods Greenland Interstadial (GI) 8 to Greenland Stadial (GS) 8 and GI 1–GS 1 (Bolling–Younger Dryas) were strikingly similar, which leads us to suggest that the underlying causes of these climate shifts could have been the same. We therefore discuss some aspects of glacial fluctuations during the Bolling–Younger Dryas in order to elucidate processes during Dansgaard–Oeschger events.
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14C‐dated fluctuations of the western flank of the Scandinavian Ice Sheet 45–25 kyr BP compared with Bølling–Younger Dryas fluctuations and Dansgaard–Oeschger events in Greenland
Boreas, 2010Co-Authors: Jan Mangerud, Steinar Gulliksen, Eiliv LarsenAbstract:Mangerud, J., Gulliksen, S. & Larsen, E. 2009: 14C-dated fluctuations of the western flank of the Scandinavian Ice Sheet 45–25 kyr BP compared with Bolling–Younger Dryas fluctuations and Dansgaard–Oeschger events in Greenland. Boreas, 10.1111/j.1502-3885.2009.00127.x. ISSN 0300-9483. We present 32 accelerator mass spectrometry (AMS) 14C dates obtained on well-preserved bones from caves in western Norway. The resulting ages of 34–28 14C kyr BP demonstrate that the coast was Ice-free during the so-called Alesund Interstadial. New AMS 14C dates on shells aged 41–38 14C kyr BP are evidence of an earlier (Austnes) Ice-free period. The Alesund Interstadial correlates with Greenland interstadials 8–7 and the Austnes Interstadial with Greenland interstadials 12–11. Between and after the two interstadials, the Ice margin reached onto the continental shelf west of Norway. These events can be closely correlated with the Greenland Ice core stratigraphy, partly based on identification of the Laschamp and Mono Lake palaeomagnetic excursions. We found that the pattern of the NGRIP δ18O curves for the two periods Greenland Interstadial (GI) 8 to Greenland Stadial (GS) 8 and GI 1–GS 1 (Bolling–Younger Dryas) were strikingly similar, which leads us to suggest that the underlying causes of these climate shifts could have been the same. We therefore discuss some aspects of glacial fluctuations during the Bolling–Younger Dryas in order to elucidate processes during Dansgaard–Oeschger events.
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Thickness evolution of the Scandinavian Ice Sheet during the Late Weichselian in Nordfjord, western Norway: evidence from Ice‐flow modeling
Boreas, 2008Co-Authors: Cornelia Winguth, Eiliv Larsen, David M. Mickelson, Jessica R. Darter, Carolyn A. Moeller, Knut StalsbergAbstract:Winguth, C., Mickelson, D. M., Larsen, E., Darter, J. R., Moeller, C. A. & Stalsberg, K. 2005 (May): Thickness evolution of the Scandinavian Ice Sheet during the Late Weichselian in Nordfjord, western Norway: evidence from Ice-flow modeling. Boreas, Vol. 34, pp. 176–185. Oslo. ISSN 0300–9483. Results from experiments with a two-dimensional Ice-flow model, applied along a west-east transect in western Norway, provide new constraints on the thickness evolution of the Scandinavian Ice Sheet throughout the Late Weichselian glaciation and deglaciation. Investigations took place along an E-W flowline of the former Ice Sheet at c. 62N, from the modern glacier Jostedalsbreen, through the Nordfjord, and across the continental shelf. A paleoclimate record from Krakenes, which is located directly at the flowline, provides temperature and precipitation information for the time between 13 800 and 9200 cal. yr BP. LGM climate conditions for the study area are estimated from various GCM studies. The GISP2 δ18O record has been tuned to the local data in order to provide a continuous temperature record as input for time-transgressive model runs. The results of all experiments suggest that the Ice did not cover the highest mountain peaks in this area, and that nunataks persisted throughout the Late Weichselian glaciation. These findings are in contrast to results from many previous model studies and other Ice-Sheet reconstructions, but agree well with minimum thickness estimates from cosmogenic dating and with vertical Ice limits inferred from lower block field boundaries and trimlines.
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late pleistocene glacial and lake history of northwestern russia
Boreas, 2006Co-Authors: Eiliv Larsen, Kurt Henrik Kjær, Igor Demidov, Kari Grosfjeld, Michael Houmarknielsen, Maria Jensen, Svend Funder, Henriette Linge, Astrid LysaAbstract:Five regionally significant Weichselian glacial events, each separated by terrestrial and marine interstadial conditions, are described from northwestern Russia. The first glacial event took place in the Early Weichselian. An Ice Sheet centred in the Kara Sea area dammed up a large lake in the Pechora lowland. Water was discharged across a threshold on the Timan Ridge and via an Ice-free corridor between the Scandinavian Ice Sheet and the Kara Sea Ice Sheet to the west and north into the Barents Sea. The next glaciation occurred around 75–70 kyr BP after an interstadial episode that lasted c. 15 kyr. A local Ice cap developed over the Timan Ridge at the transition to the Middle Weichselian. Shortly after deglaciation of the Timan Ice cap, an Ice Sheet centred in the Barents Sea reached the area. The configuration of this Ice Sheet suggests that it was confluent with the Scandinavian Ice Sheet. Consequently, around 70–65 kyr BP a huge Ice-dammed lake formed in the White Sea basin (the ‘White Sea Lake’), only now the outlet across the Timan Ridge discharged water eastward into the Pechora area. The Barents Sea Ice Sheet likely suffered marine down-draw that led to its rapid collapse. The White Sea Lake drained into the Barents Sea, and marine inundation and interstadial conditions followed between 65 and 55 kyr BP. The glaciation that followed was centred in the Kara Sea area around 55–45 kyr BP. Northward directed fluvial runoff in the Arkhangelsk region indicates that the Kara Sea Ice Sheet was independent of the Scandinavian Ice Sheet and that the Barents Sea remained Ice free. This glaciation was succeeded by a c. 20-kyr-long Ice-free and periglacial period before the Scandinavian Ice Sheet invaded from the west, and joined with the Barents Sea Ice Sheet in the northernmost areas of northwestern Russia. The study area seems to be the only region that was invaded by all three Ice Sheets during the Weichselian. A general increase in Ice-Sheet size and the westwards migrating Ice-Sheet dominance with time was reversed in Middle Weichselian time to an easterly dominated Ice-Sheet configuration. This sequence of events resulted in a complex lake history with spillways being re-used and Ice-dammed lakes appearing at different places along the Ice margins at different times.
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late pleistocene glacial and lake history of northwestern russia
Boreas, 2006Co-Authors: Eiliv Larsen, Igor Demidov, Kari Grosfjeld, Michael Houmarknielsen, Maria Jensen, Svend Funder, Henriette Linge, Kurt H. Kjær, Astrid LysaAbstract:Five regionally significant Weichselian glacial events, each separated by terrestrial and marine interstadial conditions, are described from northwestern Russia. The first glacial event took place in the Early Weichselian. An Ice Sheet centred in the Kara Sea area dammed up a large lake in the Pechora lowland. Water was discharged across a threshold on the Timan Ridge and via an Ice-free corridor between the Scandinavian Ice Sheet and the Kara Sea Ice Sheet to the west and north into the Barents Sea. The next glaciation occurred around 75–70 kyr BP after an interstadial episode that lasted c. 15 kyr. A local Ice cap developed over the Timan Ridge at the transition to the Middle Weichselian. Shortly after deglaciation of the Timan Ice cap, an Ice Sheet centred in the Barents Sea reached the area. The configuration of this Ice Sheet suggests that it was confluent with the Scandinavian Ice Sheet. Consequently, around 70–65 kyr BP a huge Ice-dammed lake formed in the White Sea basin (the ‘White Sea Lake’), only now the outlet across the Timan Ridge discharged water eastward into the Pechora area. The Barents Sea Ice Sheet likely suffered marine down-draw that led to its rapid collapse. The White Sea Lake drained into the Barents Sea, and marine inundation and interstadial conditions followed between 65 and 55 kyr BP. The glaciation that followed was centred in the Kara Sea area around 55–45 kyr BP. Northward directed fluvial runoff in the Arkhangelsk region indicates that the Kara Sea Ice Sheet was independent of the Scandinavian Ice Sheet and that the Barents Sea remained Ice free. This glaciation was succeeded by a c. 20-kyr-long Ice-free and periglacial period before the Scandinavian Ice Sheet invaded from the west, and joined with the Barents Sea Ice Sheet in the northernmost areas of northwestern Russia. The study area seems to be the only region that was invaded by all three Ice Sheets during the Weichselian. A general increase in Ice-Sheet size and the westwards migrating Ice-Sheet dominance with time was reversed in Middle Weichselian time to an easterly dominated Ice-Sheet configuration. This sequence of events resulted in a complex lake history with spillways being re-used and Ice-dammed lakes appearing at different places along the Ice margins at different times.
John Inge Svendsen - One of the best experts on this subject based on the ideXlab platform.
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Tracing the last remnants of the Scandinavian Ice Sheet: Ice-dammed lakes and a catastrophic outburst flood in northern Sweden
Quaternary Science Reviews, 2019Co-Authors: Carl Regnéll, Jan Mangerud, John Inge SvendsenAbstract:Abstract We present geomorphological evidence of large, previously undocumented, early Holocene Ice-dammed lakes in the Scandinavian Mountains of northwestern Sweden. The lakes extents indicate that the last remnants of the Scandinavian Ice Sheet were located east of the mountain range. Some early pioneering works have presented similar reconstructions, whereas more recently published reconstructions place the last Ice remnants in the high mountains of Sarek. Using high-resolution airborne LiDAR data we have mapped a large number of hitherto undocumented shorelines in some of the main valleys within the northern Scandinavian mountain range. Our results indicate that a larger system of Ice-dammed lakes existed in this region than previously thought. The lakes were dammed between the main water divide to the west and the retreating Ice Sheet margin to the east. The shorelines dip towards the northwest with gradients ranging from 0.5 to 0.4 m/km, from the oldest to the youngest. Further, we have compiled Lateglacial and Holocene shoreline data along the Norwegian coast and from within the Baltic Sea basin and reconstructed the isostatic uplift along a 1400 km long northwest-southeast transect from the Norwegian Sea to Lake Ladoga. By comparing the measured Ice-dammed lake shoreline gradients to the dated marine shorelines, we infer that the lakes may have existed for several centuries following 10.2 cal ka BP. We also describe large deposits and extensive erosive features, which demonstrate that a catastrophic glacial lake outburst flood (GLOF) took place eastward along the Pite River Valley. Based on cross-cutting relations to raised shorelines developed in the early Holocene Ancylus Lake (Baltic Sea basin) we conclude that the flood and thus the final phase of deglaciation took place within the time interval 10.3–9.9 cal ka BP.
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Atmosphere-driven Ice Sheet mass loss paced by topography: Insights from modelling the south-western Scandinavian Ice Sheet
Quaternary Science Reviews, 2018Co-Authors: Henning Åkesson, John Inge Svendsen, Mathieu Morlighem, Kerim H. Nisancioglu, Jan MangerudAbstract:Abstract Marine-terminating glaciers and Ice streams are important controls of Ice Sheet mass balance. However, understanding of their long-term response to external forcing is limited by relatively short observational records of present-day glaciers and sparse geologic evidence for paleo-glaciers. Here we use a high-resolution Ice Sheet model with an accurate representation of grounding line dynamics to study the deglaciation of the marine-based south-western Norwegian sector of the Scandinavian Ice Sheet and its sensitivity to ocean and atmosphere forcing. We find that the regional response to a uniform climate change is highly dependent on the local bedrock topography, consistent with Ice Sheet reconstructions. Our simulations suggest that ocean warming is able to trigger initial retreat in several fjords, but is not sufficient to explain retreat everywhere. Widespread retreat requires additional Ice thinning driven by surface melt. Once retreat is triggered, the underlying bedrock topography and fjord width control the rate and extent of retreat, while multi-millennial changes over the course of deglaciation are modulated by surface melt. We suggest that fjord geometry, Ice-ocean interactions and grounding line dynamics are vital controls of decadal-to centennial scale Ice Sheet mass loss. However, we postulate that atmospheric changes are the most important drivers of widespread Ice Sheet demise, and will likely trump oceanic influence on future Ice Sheet mass loss and resulting sea level rise over centennial and longer time scales.
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A major re-growth of the Scandinavian Ice Sheet in western Norway during Allerød-Younger Dryas
Quaternary Science Reviews, 2016Co-Authors: Jan Mangerud, Inge Aarseth, Anna L.c. Hughes, Øystein S. Lohne, Kåre Skår, Eivind Sønstegaard, John Inge SvendsenAbstract:Abstract Distinct Younger Dryas (YD) moraines are mapped more-or-less continuously around the Scandinavian Ice Sheet. In most areas there is no evidence to suggest that a glacial re-advance took place during the YD, either because it did not happen or because older deposits have been removed by glacial erosion. In contrast we here present 90 radiocarbon dates from 36 different sites that were overrun by a major Ice Sheet advance in the area between Hardangerfjorden and Sognefjorden, SW Norway. Thus this region is exceptional for examining the glacial response to the climate shifts across Allerod-YD. The re-growth of the Ice Sheet in this sector commenced during the Allerod Interstadial. It expanded along 600–800 m deep fjords reaching a thickness of up to 2000 m. We produce time–distance diagrams for two lobes; for both the outermost coast became Ice free close to 15 cal ka BP, i.e. at the onset of the Bolling. The Hardangerfjorden Lobe re-advanced during the Older Dryas (14 cal ka BP), an event that was not replicated for the Herdla Lobe farther north. Both lobes reached their most landward position before re-advancing at 13.5–13.0 cal ka and obtained their maximum extent at the very end of the YD, 11.5 cal ka. The late culmination of the advance is accurately dated and differs from most of the Scandinavian Ice Sheet margin where the maximum was reached during early or middle YD. We also present a time–distance diagram from the Last Glacial Maximum to the Ice divide showing two-step retreat; fast retreat occurs 21–20 and 11.5–10 cal ka BP separated by a period of almost no net retreat 20–11.5 cal ka BP, which contrasts with much more even retreat in other parts of the Scandinavian Ice Sheet.
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Early break-up of the Norwegian Channel Ice Stream during the Last Glacial Maximum
Quaternary Science Reviews, 2015Co-Authors: John Inge Svendsen, Jan Mangerud, Jason P. Briner, Nicolás E. YoungAbstract:10Be dating Last Glacial Maximum abstract We present 18 new cosmogenic 10 Be exposure ages that constrain the breakup time of the Norwegian Channel Ice Stream (NCIS) and the initial retreat of the Scandinavian Ice Sheet from the Southwest coast of Norway following the Last Glacial Maximum (LGM). Seven samples from glacially transported erratics on the island Utsira, located in the path of the NCIS about 400 km up-flow from the LGM Ice front position, yielded an average 10 Be age of 22.0 ± 2.0 ka. The distribution of the ages is skewed with the 4 youngest all within the range 20.2e20.8 ka. We place most confidence on this cluster of ages to constrain the timing of Ice Sheet retreat as we suspect the 3 oldest ages have some inheritance from a previous Ice free period. Three additional ages from the adjacent island Karmoy provided an average age of 20.9 ± 0.7 ka, further supporting the new timing of retreat for the NCIS. The 10 Be ages from Utsira and Karmoy suggest that the Ice stream broke up about 2000 years earlier than the age assignment based on 14 C ages on foraminifera and molluscs from marine sediment cores. We postulate that the Scandinavian Ice Sheet flowed across the Norwegian Channel to Denmark and onto the North Sea plateau during early phases of the LGM. When the NCIS started to operate this Ice supply to the North Sea was cut off and the fast flow of the NCIS also led to a lowering of the Ice surface along the Norwegian Channel and thereby drawdown of the entire Ice Sheet. This facilitated rapid calving of the Ice front in the North Sea and we reconstruct a large open bay across the entire northern North Sea by ~20 ka based on our 10 Be ages in the
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A 10Be chronology of south‐western Scandinavian Ice Sheet history during the Lateglacial period
Journal of Quaternary Science, 2014Co-Authors: Jason P. Briner, Jan Mangerud, Øystein S. Lohne, John Inge Svendsen, Nicolás E. YoungAbstract:We present 34 new cosmogenic 10Be exposure ages that constrain the Lateglacial (Bolling–Preboreal) history of the Scandinavian Ice Sheet in the Lysefjorden region, south-western Norway. We find that the classical Lysefjorden moraines, earlier thought to be entirely of Younger Dryas age, encompass three adjacent moraines attributed to at least two Ice Sheet advances of distinctly different ages. The 10Be age of the outermost moraine (14.0 ± 0.6 ka; n = 4) suggests that the first advance is of Older Dryas age. The innermost moraine is at least 2000 years younger and was deposited near the end of the Younger Dryas (11.4 ± 0.4 ka; n = 7). After abandonment of the innermost Lysefjorden Moraine, the Ice front receded quickly towards the head of the fjord, where recession was interrupted by an advance that deposited the Trollgaren Moraine at 11.3 ± 0.9 ka (n = 5). 10Be ages from the inboard side of the Trollgaren Moraine suggest final retreat by 10.7 ± 0.3 ka (n = 7). The late culmination of the Younger Dryas advance contrasts with other sectors of the Scandinavian Ice Sheet where the margin appears to have culminated earlier during the Younger Dryas stadial, followed by retreat during the middle and late part of the Younger Dryas.
Juha Pekka Lunkka - One of the best experts on this subject based on the ideXlab platform.
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Final deglaciation of the Scandinavian Ice Sheet and implications for the Holocene global sea-level budget
Earth and Planetary Science Letters, 2016Co-Authors: Joshua K. Cuzzone, Juha Pekka Lunkka, Vincent Rinterknecht, Peter U. Clark, Anders E. Carlson, David J. Ullman, Glenn A. Milne, Barbara Wohlfarth, Shaun A. Marcott, Marc W. CaffeeAbstract:Abstract The last deglaciation of the Scandinavian Ice Sheet (SIS) from ∼ 21 , 000 to 13,000 yr ago is well-constrained by several hundred 10Be and 14C ages. The subsequent retreat history, however, is established primarily from minimum-limiting 14C ages and incomplete Baltic-Sea varve records, leaving a substantial fraction of final SIS retreat history poorly constrained. Here we develop a high-resolution chronology for the final deglaciation of the SIS based on 79 10Be cosmogenic exposure dates sampled along three transects spanning southern to northern Sweden and Finland. Combining this new chronology with existing 10Be ages on deglaciation since the Last Glacial Maximum shows that rates of SIS margin retreat were strongly influenced by deglacial millennial-scale climate variability and its effect on surface mass balance, with regional modulation of retreat associated with dynamical controls. Ice-volume estimates constrained by our new chronology suggest that the SIS contributed ∼ 8 m sea-level equivalent to global sea-level rise between ∼14.5 ka and 10 ka. Final deglaciation was largely complete by ∼10.5 ka, with highest rates of sea-level rise occurring during the Bolling–Allerod, a 50% decrease during the Younger Dryas, and a rapid increase during the early Holocene. Combining our SIS volume estimates with estimated contributions from other remaining Northern Hemisphere Ice Sheets suggests that the Antarctic Ice Sheet (AIS) contributed 14.4 ± 5.9 m to global sea-level rise since ∼13 ka. This new constraint supports those studies that indicate that an Ice volume of 15 m or more of equivalent sea-level rise was lost from the AIS during the last deglaciation.
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the rautuvaara section western finnish lapland revisited new age constraints indicate a complex Scandinavian Ice Sheet history in northern fennoscandia during the weichselian stage
Boreas, 2015Co-Authors: Juha Pekka Lunkka, Pertti Sarala, Philip L. GibbardAbstract:The Rautuvaara section in northern Finnish Lapland has been widely considered as the stratotype for the northern Fennoscandian late Middle and Late Pleistocene. It exposes four till units interbedded with sorted sediments resting on Precambrian bedrock. In order to shed light on the Scandinavian Ice Sheet (SIS) history and palaeoenvironmental evolution in northern Fennoscandia through time, a chronostratigraphical study was carried out at the Rautuvaara site. The succession was studied using sedimentological methods and different sand-rich units between till units were dated using the Optical Stimulated Luminescence (OSL) method. The results obtained indicate that the whole sediment succession at Rautuvaara was deposited during the Weichselian Stage and there is no indication of older deposits. The SIS advanced across Finnish Lapland to adjacent areas to the east at least once during the Early Weichselian, twIce during the Middle Weichselian (∼MIS 4 and MIS 3) and once during the Late Weichselian substages. Glaciolacustrine sediments interbedded between the till units indicate that a glacial lake repeatedly existed after each deglacial phase. The results also suggest that there were two Ice-free intervals in northern Fennoscandia during the Middle Weichselian close to the SIS glaciation centre.
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The Rautuvaara section, western Finnish Lapland, revisited – new age constraints indicate a complex Scandinavian Ice Sheet history in northern Fennoscandia during the Weichselian Stage
Boreas, 2014Co-Authors: Juha Pekka Lunkka, Pertti Sarala, Philip L. GibbardAbstract:The Rautuvaara section in northern Finnish Lapland has been widely considered as the stratotype for the northern Fennoscandian late Middle and Late Pleistocene. It exposes four till units interbedded with sorted sediments resting on Precambrian bedrock. In order to shed light on the Scandinavian Ice Sheet (SIS) history and palaeoenvironmental evolution in northern Fennoscandia through time, a chronostratigraphical study was carried out at the Rautuvaara site. The succession was studied using sedimentological methods and different sand-rich units between till units were dated using the Optical Stimulated Luminescence (OSL) method. The results obtained indicate that the whole sediment succession at Rautuvaara was deposited during the Weichselian Stage and there is no indication of older deposits. The SIS advanced across Finnish Lapland to adjacent areas to the east at least once during the Early Weichselian, twIce during the Middle Weichselian (∼MIS 4 and MIS 3) and once during the Late Weichselian substages. Glaciolacustrine sediments interbedded between the till units indicate that a glacial lake repeatedly existed after each deglacial phase. The results also suggest that there were two Ice-free intervals in northern Fennoscandia during the Middle Weichselian close to the SIS glaciation centre.
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Middle Weichselian glacial event in the central part of the Scandinavian Ice Sheet recorded in the Hitura pit, Ostrobothnia, Finland
Boreas, 2008Co-Authors: Veli-pekka Salonen, Anu Kaakinen, Seija Kultti, Arto Miettinen, K. Eskola, Juha Pekka LunkkaAbstract:The Hitura open pit exposes a sedimentary sequence up to 50 m thick representing Late Saalian to Holocene glacial and non-glacial sediments. The sequence was investigated using sedimentological methods, OSL-dating and pollen and diatom analyses to reconstruct the Middle Weichselian (MWG) glacial event in the central part of the Scandinavian Ice Sheet (SIS). The results indicate that the sediment succession represents two entire glacial advance and retreat cycles. The lowermost deposits are Late Saalian esker and delta sediments overlain by sediments that correlate with the early Eemian lacustrine phase. Remnants of the Eemian soil post-dating the lacustrine phase were also observed. The area was Ice-free during the entire Early Weichselian (EWG). The first glacial advance recorded in the sediments is related to the MWG. It started 79 kyr ago, deformed underlying sediments and deposited an immature till, including large detached sediment pods containing remains of organic material, soils and fluvial sediments representing allochthonous material from EWG Ice-free stadials and interstadials. The glacial deposits are conformably overlain by glaciolacustrine and littoral accumulations, indicating MWG deglaciation between 62 and 55 kyr ago. Based on the fabric measurements from the till unit overlying the MWG sediments, Ice advance during the Late Weichselian (LWG) was initially from the west and later from a north-northwesterly direction. The Hitura strata provide the first dating of the MWG deglaciation (55 to 62 kyr ago) from central parts of the SIS. It can be considered as a key site for studying the growth and decay of SIS during the poorly known early parts of the glaciation.
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The last deglaciation of the southeastern sector of the Scandinavian Ice Sheet.
Science (New York N.Y.), 2006Co-Authors: Vincent Rinterknecht, Juha Pekka Lunkka, Peter U. Clark, Grant M. Raisbeck, Françoise Yiou, Albertas Bitinas, Edward J. Brook, Leszek Marks, Vitālijs Zelčs, Irina E. PavlovskayaAbstract:The Scandinavian Ice Sheet (SIS) was an important component of the global Ice Sheet system during the last glaciation, but the timing of its growth to or retreat from its maximum extent remains poorly known. We used 115 cosmogenic beryllium-10 ages and 70 radiocarbon ages to constrain the timing of three substantial Ice-margin fluctuations of the SIS between 25,000 and 12,000 years before the present. The age of initial deglaciation indicates that the SIS may have contributed to an abrupt rise in global sea level. Subsequent Ice-margin fluctuations identify opposite mass-balance responses to North Atlantic climate change, indicating differing Ice-Sheet sensitivities to mean climate state.
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The sea cliff at Dwasieden: soft-sediment deformation structures triggered by glacial isostatic adjustment in front of the advancing Scandinavian Ice Sheet
DEUQUA Special Publications, 2019Co-Authors: Małgorzata Pisarska-jamroży, Szymon Belzyt, Andreas Börner, Gösta Hoffmann, Heiko Hüneke, Michael Kenzler, Karsten Obst, Henrik Rother, Holger Steffen, Rebekka SteffenAbstract:Abstract. Isostatic response of the Earth's crust as a consequence of the fluctuating extent of Ice-Sheet masses was accompanied by earthquakes probably due to local reactivation of pre-existing faults. Our study of a glacilacustrine and glacifluvial succession exposed on Rugen Island (SW Baltic Sea) indicates that some of the soft-sediment deformation structures within the succession must have formed shortly before the front of the Pleistocene Scandinavian Ice Sheet reached the study area (during the Last Glacial Maximum), thus during a stage of Ice advance. Based on analysis of the textural and structural features of the soft-sediment deformation structures, the deformed layers under investigation are interpreted as seismites which formed as a result of seismically induced liquefaction and fluidisation.
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Sea cliff at Glowe: stratigraphy and absolute age chronology of the Jasmund Pleistocene sedimentary record
DEUQUA Special Publications, 2019Co-Authors: Michael Kenzler, Heiko HünekeAbstract:Abstract. Four remarkable Pleistocene cliff outcrops scattered across the peninsula of Jasmund exhibit the dynamics of the Scandinavian Ice Sheet during the Weichselian glaciation in this area. The investigated sites display up to 30 m thick sequences of glacial tills with intercalated (glaci)fluvial to (glaci)lacustrine sediments. Based on detailed lithofacies analyses and a physical age chronology, we trace the reconstruction of the depositional sequences and their corresponding stratigraphic position within the Weichselian record.
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Micromorphology and clast microfabrics of subglacial traction tills at the sea cliff Dwasieden: evidence of polyphase syn- and post-depositional deformation
DEUQUA Special Publications, 2019Co-Authors: Johannes Brumme, Heiko Hüneke, Emrys PhillipsAbstract:Abstract. A detailed thin-section-based micromorphological and microstructural study of the glacial diamicts exposed at the sea cliff of Dwasieden (M1, M2, M2) has revealed that all units can be related, in their entirety or in several parts, to subglacial conditions during the repeated readvance of the Scandinavian Ice Sheet. These readvances are characterised by polyphase deformation of the diamicts resulting in the development of ductile and brittle structures and localised water-escape structures. Subsequent alteration under periglacial conditions has been documented for the chalk and till units M1 and M2.
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new age constraints from the sw baltic sea area implications for Scandinavian Ice Sheet dynamics and palaeo environmental conditions during mis 3 and early mis 2
Boreas, 2017Co-Authors: Michael Kenzler, Sumiko Tsukamoto, Stefan Meng, Manfred Frechen, Heiko HünekeAbstract:The study of two cliff outcrops from the Jasmund Peninsula provides new information on the Ice-Sheet dynamics and palaeo-environmental conditions during MIS 3 and the ensuing transition to MIS 2 in the southwestern Baltic Sea region. We identified interstadial fluvial sediments, with mollusc and vertebrate fauna, which were deposited between 47 and 42 ka in a steppe-like landscape. A subsequent cooling phase led to the formation of a proglacial lake, between 30 and 22 ka, indicated by varve-like, rhythmically bedded silty clay. This proglacial lake formation can be correlated to the blocking of the Baltic Basin by the Kattegat Ice advance, previously dated to c. 29–26 ka. The transition from proglacial to terminoglacial lacustrine deposits reflects the immediate advance of the Scandinavian Ice Sheet (SIS) into the study area after the transition from MIS 3 to early MIS 2. The SIS finally reached the area at 23±2 ka (Brandenburgian phase; advance from the northeast). A subsequent Ice retreat accompanied by the deposition of meltwater sediments was followed by a re-advance of the SIS, resulting in a glaciotectonic deformation event across the study area. The age control for our study is based on optically stimulated luminescence (OSL). The investigated Pleistocene sediments show Ice-free conditions during MIS 3 and early MIS 2, indicating that neither the Ristinge nor the Klintholm advance reached the SW Baltic Sea coast of Jasmund.
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New age constraints from the SW Baltic Sea area – implications for Scandinavian Ice Sheet dynamics and palaeo‐environmental conditions during MIS 3 and early MIS 2
Boreas, 2016Co-Authors: Michael Kenzler, Sumiko Tsukamoto, Stefan Meng, Manfred Frechen, Heiko HünekeAbstract:The study of two cliff outcrops from the Jasmund Peninsula provides new information on the Ice-Sheet dynamics and palaeo-environmental conditions during MIS 3 and the ensuing transition to MIS 2 in the southwestern Baltic Sea region. We identified interstadial fluvial sediments, with mollusc and vertebrate fauna, which were deposited between 47 and 42 ka in a steppe-like landscape. A subsequent cooling phase led to the formation of a proglacial lake, between 30 and 22 ka, indicated by varve-like, rhythmically bedded silty clay. This proglacial lake formation can be correlated to the blocking of the Baltic Basin by the Kattegat Ice advance, previously dated to c. 29–26 ka. The transition from proglacial to terminoglacial lacustrine deposits reflects the immediate advance of the Scandinavian Ice Sheet (SIS) into the study area after the transition from MIS 3 to early MIS 2. The SIS finally reached the area at 23±2 ka (Brandenburgian phase; advance from the northeast). A subsequent Ice retreat accompanied by the deposition of meltwater sediments was followed by a re-advance of the SIS, resulting in a glaciotectonic deformation event across the study area. The age control for our study is based on optically stimulated luminescence (OSL). The investigated Pleistocene sediments show Ice-free conditions during MIS 3 and early MIS 2, indicating that neither the Ristinge nor the Klintholm advance reached the SW Baltic Sea coast of Jasmund.
