scholarly journals Quaternary observations in southern Peary Land, North Greenland

1976 ◽  
Vol 80 ◽  
pp. 15-17
Author(s):  
A Weidick
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Primary Objective ◽  
Drilling Operation ◽  
Ice Cap ◽  
History Of ◽  
Quaternary History ◽  
Work Done ◽  
North Greenland

A geological group consisting of the author and P. R.Dawes accompanied the 1975 Greenland Ice Sheet Programme's (GISP) ice drilling operation at Hans Tavsens Iskappe, south-westem Peary Land. The primary objective of the group was to investigate the Quaternary history of the area south of the ice cap as a supplement to the work done elsewhere in Peary Land by the various Peary Land Expeditions (Troelsen, 1952; Kirkeby, 1963: Fredskild, 1969), Operations Groundhog and Lead Dog (Stoertz & Needleman, 1957; Davies, 1972; Ahnert, 1960) and the British Joint Services Expedition (Dawes, 1970).

scholarly journals Glacial history of Inglefield Land, north Greenland from combined in-situ <sup>10</sup>Be and <sup>14</sup>C exposure dating

2020 ◽  
Author(s):  
Anne Sofie Søndergaard ◽  
Nicolaj Krog Larsen ◽  
Olivia Steinemann ◽  
Jesper Olsen ◽  
Svend Funder ◽  
...  
Keyword(s):  
Climate Changes ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Glacial History ◽  
Holocene Climate ◽  
Exposure Dating ◽  
History Of ◽  
North Greenland

Abstract. Exposing the sensitivity of the Greenland Ice Sheet (GrIS) to Holocene climate changes is a key prerequisite for understanding the future response of the ice sheet to global warming. In this study, we present new information on the Holocene glacial history of the GrIS in Inglefield Land, north Greenland. We use 10Be and in-situ 14C exposure dating to constrain the timing of deglaciation in the area and radiocarbon dating of reworked molluscs and wood fragments to constrain when the ice sheet retreated behind its present-day extent. The 10Be ages are scattered ranging from c. 92.7 to 6.8 ka whereas the in-situ 14C ages range from c. 14.2 to 6.7 ka. Almost half of the apparent 10Be ages predate the Last Glacial Maximum and up to 89 % are to some degree affected by nuclide inheritance. Based on the few reliable 10Be ages, the in-situ 14C ages and existing radiocarbon ages from Inglefield Land, we find that the deglaciation along the coast commenced c. 8.6–8.3 cal. ka BP in the western part and c. 7.9 ka in the central part, following the opening of Nares Strait and arrival of warm waters. The ice margin reached its present-day position c. 8.2 ka at the Humboldt Glacier and c. 6.7 ka in the central part of Inglefield Land. Radiocarbon ages of reworked molluscs and wood fragments show that the ice margin was behind its present-day extent from c. 5.8 to 0.5 cal. ka BP. After 0.5 cal. ka BP, the ice advanced towards its Little Ice Age position. Our results emphasize that the slowly eroding and possibly cold-based ice in north Greenland makes it difficult to constrain the deglaciation history based on 10Be ages alone unless it is paired with in-situ 14C ages. Further, combining our findings with those of recently published studies reveals distinct differences between deglaciation patterns of northwest and north Greenland. Deglaciation of the land areas in northwest Greenland occurred earlier than in north Greenland and periods of restricted ice extent were longer, spanning middle and late Holocene. Overall, this highlights past ice sheet sensitivity towards Holocene climate changes in an area where little information was available just a few years ago.

scholarly journals The timing of fjord formation and early glaciations in North and Northeast Greenland

2020 ◽  
Author(s):  
Vivi Kathrine Pedersen ◽  
Nicolaj Krog Larsen ◽  
David Lundbek Egholm
Keyword(s):  
Late Miocene ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early History ◽  
Early Pleistocene ◽  
Late Pliocene ◽  
Isostatic Uplift ◽  
History Of ◽  
Erosional Unloading ◽  
North Greenland

&lt;p&gt;The timing and extent of early glaciations in Greenland, and their co-evolution with the underlying landscape remain elusive. In this study, we explore the timing of fjord erosion in Northeast and North Greenland between Scoresby Sund (70&amp;#176;N) and Independence Fjord (82&amp;#176;N). By determining the timing of fjord formation, we can improve our understanding of the early history of the Greenland Ice Sheet in these regions.&lt;/p&gt;&lt;p&gt;We use the concept of geophysical relief to estimate fjord erosion and calculate the subsequent flexural isostatic response to erosional unloading. The timing of erosion and isostatic uplift is constrained by marine sediments of late Pliocene-early Pleistocene age that are now exposed on land between ~24 and 230 m a.s.l.&lt;/p&gt;&lt;p&gt;We find that the northern Independence Fjord system must have formed by glacial erosion at average rates of ~0.5-1 mm/yr since ~2.5 Ma, in order to explain the current elevation of the marine Kap K&amp;#248;benhavn Formation by erosion-induced isostatic uplift. In contrast, fjord formation in the outer parts of southward Scoresby Sund commenced before the Pleistocene, most likely in late Miocene, and continued throughout the Pleistocene by fjord formation progressing inland. Our results suggest that the inception of the Greenland Ice Sheet began in the central parts of Northeast Greenland before the Pleistocene and spread to North Greenland only at the onset of the Pleistocene. &amp;#160;&lt;/p&gt;

scholarly journals Glacial history of Inglefield Land, north Greenland from combined in situ <sup>10</sup>Be and <sup>14</sup>C exposure dating

2020 ◽  
Vol 16 (5) ◽  
pp. 1999-2015
Author(s):  
Anne Sofie Søndergaard ◽  
Nicolaj Krog Larsen ◽  
Olivia Steinemann ◽  
Jesper Olsen ◽  
Svend Funder ◽  
...  
Keyword(s):  
Climate Changes ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Glacial History ◽  
Holocene Climate ◽  
Exposure Dating ◽  
History Of ◽  
North Greenland

Abstract. Determining the sensitivity of the Greenland Ice Sheet (GrIS) to Holocene climate changes is a key prerequisite for understanding the future response of the ice sheet to global warming. In this study, we present new information on the Holocene glacial history of the GrIS in Inglefield Land, north Greenland. We use 10Be and in situ 14C exposure dating to constrain the timing of deglaciation in the area and radiocarbon dating of reworked molluscs and wood fragments to constrain when the ice sheet retreated behind its present-day extent. The 10Be ages are scattered ranging from ca. 92.7 to 6.8 ka, whereas the in situ 14C ages range from ca. 14.2 to 6.7 ka. Almost half of the apparent 10Be ages predate the Last Glacial Maximum and up to 89 % are to some degree affected by nuclide inheritance. Based on the few reliable 10Be ages, the in situ 14C ages and existing radiocarbon ages from Inglefield Land, we find that the deglaciation along the coast commenced at ca. 8.6–8.3 ka cal BP in the western part and ca. 7.9 ka in the central part, following the opening of Nares Strait and arrival of warm waters. The ice margin reached its present-day position at ca. 8.2 ka at the Humboldt Glacier and ca. 6.7 ka in the central part of Inglefield Land. Radiocarbon ages of reworked molluscs and wood fragments show that the ice margin was behind its present-day extent from ca. 5.8 to 0.5 ka cal BP. After 0.5 ka cal BP, the ice advanced towards its Little Ice Age position. Our results emphasize that the slowly eroding and possibly cold-based ice in north Greenland makes it difficult to constrain the deglaciation history based on 10Be ages alone unless they are paired with in situ 14C ages. Further, combining our findings with those of recently published studies reveals distinct differences between deglaciation patterns of northwest and north Greenland. Deglaciation of the land areas in northwest Greenland occurred earlier than in north Greenland, and periods of restricted ice extent were longer, spanning the Middle and Late Holocene. Overall, this highlights past ice sheet sensitivity to Holocene climate changes in an area where little information was available just a few years ago.

scholarly journals Glacial history of the Greenland Ice Sheet and a local ice cap in Qaanaaq, northwest Greenland

2019 ◽  
Vol 34 (7) ◽  
pp. 536-547 ◽  
Author(s):  
Anne Sofie Søndergaard ◽  
Nicolaj Krog Larsen ◽  
Jesper Olsen ◽  
Astrid Strunk ◽  
Sarah Woodroffe
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Glacial History ◽  
Ice Cap ◽  
History Of

scholarly journals The timing of fjord formation and early glaciations in North and Northeast Greenland

2021 ◽  
Author(s):  
Vivi Kathrine Pedersen ◽  
Nicolaj Krog Larsen ◽  
David Lundbek Egholm
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early History ◽  
Early Pleistocene ◽  
East Greenland ◽  
Late Pliocene ◽  
Isostatic Uplift ◽  
History Of ◽  
Erosional Unloading ◽  
North Greenland

&lt;p&gt;The timing and extent of early glaciations in Greenland, and their co-evolution with the underlying landscape remain elusive. In this study, we explore the timing of fjord formation in Northeast and North Greenland, between Scoresby Sund (70&amp;#176;N) and Independence Fjord (82&amp;#176;N). By determining the timing of fjord formation, we can improve our understanding of the early history of the Greenland Ice Sheet in these regions. We use the concept of geophysical relief to estimate fjord erosion volumes and calculate the subsequent flexural isostatic response to erosional unloading. The timing of erosion and isostatic uplift is constrained by marine sediments of late Pliocene-early Pleistocene age that are now exposed on land between ~24 and 230 m a.s.l. The late Pliocene-early Pleistocene sediments themselves attest to a time of limited ice cover in Greenland, with temperatures as much as 6-8 &amp;#176;C higher than present (e.g. Bennike et al., 2010).&lt;/p&gt;&lt;p&gt;We find that the northern Independence Fjord system must have formed by glacial erosion since the deposition of the marine late Pliocene-early Pleistocene sediments at ~2.5 Ma, in order to explain the current elevation of the sediments by erosion-induced isostatic uplift. In contrast, fjord formation in the outer parts of southward Scoresby Sund commenced prior to the Pleistocene, most likely in late Miocene, and continued throughout the Pleistocene with fjord formation progressing inland. Our results suggest that the inception of the Greenland Ice Sheet began in the central parts of Northeast Greenland before the Pleistocene and spread to North Greenland only at the onset of the Pleistocene.&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Bennike, O., Knudsen, K.L., Abrahamsen, N., B&amp;#246;cher, J., Cremer, H., and Wagner, B., 2010, Early Pleistocene sediments on Store Koldewey, north&amp;#173;east Greenland: Boreas v. 39, p. 603&amp;#8211;619, https://doi.org /10.1111/j.1502-3885.2010.00147.x.&lt;/p&gt;

scholarly journals How warm was Greenland during the last interglacial period?

2016 ◽  
Vol 12 (9) ◽  
pp. 1933-1948 ◽  
Author(s):  
Amaelle Landais ◽  
Valérie Masson-Delmotte ◽  
Emilie Capron ◽  
Petra M. Langebroek ◽  
Pepijn Bakker ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Water Isotopes ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Last Interglacial Period ◽  
Ice Sheet Topography ◽  
North Greenland

Abstract. The last interglacial period (LIG, ∼ 129–116 thousand years ago) provides the most recent case study of multimillennial polar warming above the preindustrial level and a response of the Greenland and Antarctic ice sheets to this warming, as well as a test bed for climate and ice sheet models. Past changes in Greenland ice sheet thickness and surface temperature during this period were recently derived from the North Greenland Eemian Ice Drilling (NEEM) ice core records, northwest Greenland. The NEEM paradox has emerged from an estimated large local warming above the preindustrial level (7.5 ± 1.8 °C at the deposition site 126 kyr ago without correction for any overall ice sheet altitude changes between the LIG and the preindustrial period) based on water isotopes, together with limited local ice thinning, suggesting more resilience of the real Greenland ice sheet than shown in some ice sheet models. Here, we provide an independent assessment of the average LIG Greenland surface warming using ice core air isotopic composition (δ15N) and relationships between accumulation rate and temperature. The LIG surface temperature at the upstream NEEM deposition site without ice sheet altitude correction is estimated to be warmer by +8.5 ± 2.5 °C compared to the preindustrial period. This temperature estimate is consistent with the 7.5 ± 1.8 °C warming initially determined from NEEM water isotopes but at the upper end of the preindustrial period to LIG temperature difference of +5.2 ± 2.3 °C obtained at the NGRIP (North Greenland Ice Core Project) site by the same method. Climate simulations performed with present-day ice sheet topography lead in general to a warming smaller than reconstructed, but sensitivity tests show that larger amplitudes (up to 5 °C) are produced in response to prescribed changes in sea ice extent and ice sheet topography.

scholarly journals Measurements of firn density in the lower accumulation area of the Greenland ice sheet: EPOCH 1992

1993 ◽  
Vol 159 ◽  
pp. 62-65
Author(s):  
R.J Braithwaite ◽  
M Laternser
Keyword(s):  
Sea Level ◽  
Natural Hazards ◽  
European Community ◽  
Present Note ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Field Work ◽  
Sea Level Changes ◽  
Work Done ◽  
European Programme

Groups from several countries are studying Greenland glaciers in connection with the 'greenhouse effect' (Braithwaite et al., 1992a). In particular, GGU is the Danish partner in a IO-nation two-year project (March 1991 to February 1993) on causes and effects of sea level changes which is funded by the European Community through the European Programme on Climatology and Natural Hazards (EPOCH). As its contribution to EPOCH, GGU is studying the effects of meltwater refreezing in the lower accumulation area of the Greenland ice sheet which may reduce, or at least delay, the expected sea level rise under warmer climate. Work done under EPOCH in 1991 was described by Braithwaite et al. (1992b) while the present note describes the most important results of the 1992 field work.

scholarly journals Snow Accumulation in North Greenland

1958 ◽  
Vol 3 (24) ◽  
pp. 237-248 ◽  
Author(s):  
C. Bull
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Snow Accumulation ◽  
The Mean ◽  
Precipitation Records ◽  
Available Information ◽  
North Greenland

AbstractMeasurements of the annual snow accumulation have been made at many points on a traverse of north Greenland. In lat. 77–78° N. the annual accumulation above 1800 m. was about 13 gm. cm.−2in the years 1948–53 and, in contrast to results which have been obtained further south, did not vary with longitude. In 1953–54 the accumulation was greater. The annual accumulation in north and central Greenland has varied significantly over the last 50 years, but similar variations are not shown in the precipitation records at coastal stations. Using all the available information, the mean annual accumulation on the Greenland Ice Sheet has been calculated as 29±3 gm. cm.−2.

Cenozoic Glacial and Tectonic History of the Transantarctic Mountains in the McMurdo Sound Region: Recent Progress from Drilling and Related Studies

Polar Record ◽  
1981 ◽  
Vol 20 (129) ◽  
pp. 543-548 ◽  
Author(s):  
P. J. Barrett ◽  
B. C. McKelvey
Keyword(s):  
Ross Sea ◽  
Ice Sheet ◽  
Ice Cover ◽  
Early History ◽  
Antarctic Ice Sheet ◽  
Ice Cap ◽  
Tectonic History ◽  
History Of ◽  
Transantarctic Mountains ◽  
East Antarctic Ice Sheet

Two of the outstanding problems in Antarctic earth sciences are the early history of the East Antarctic ice sheet, and the history of the Transantarctic Mountains. These two problems may well be linked, for if the initial uplift of the Transantarctic Mountains was sufficient to promote a permanent ice cap, this may have triggered formation of the East Antarctic ice sheet in the manner oudined by Drewry (1975, p 266). Glomar Challenger in 1973 made the first major breakthrough concerning early history of the ice sheet by recovering cores from the centre of the Ross Sea; they show that ice rafting began there 25 Ma BP and has been going on ever since (Hayes and others, 1975). However, the core data give little indication of the extent of ice cover, or of the climatic changes that led to expanded ice cover which produced the ice-rafted debris.

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