Holocene glacial history of the west Greenland Ice Sheet inferred from cosmogenic exposure ages and threshold lakes
Research output: Contribution to conference › Conference abstract for conference › Research
Standard
Holocene glacial history of the west Greenland Ice Sheet inferred from cosmogenic exposure ages and threshold lakes. / Larsen, Nicolaj Krog; Kjaer, K. H.; Colding, Sune Oluf; Funder, S.; Kjeldsen, Kristian Kjellerup; Odgaard, Bent Vad; Olsen, J.; Linge, H. C.
2011.Research output: Contribution to conference › Conference abstract for conference › Research
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - ABST
T1 - Holocene glacial history of the west Greenland Ice Sheet inferred from cosmogenic exposure ages and threshold lakes
AU - Larsen, Nicolaj Krog
AU - Kjaer, K. H.
AU - Colding, Sune Oluf
AU - Funder, S.
AU - Kjeldsen, Kristian Kjellerup
AU - Odgaard, Bent Vad
AU - Olsen, J.
AU - Linge, H. C.
PY - 2011/12/1
Y1 - 2011/12/1
N2 - In this study, we use a combination of 10Be exposure ages and threshold lakes to constrain the ice sheet history in Godthåbs- and Buksefjorden, west Greenland (63-64°N) during the Holocene. The 10Be cosmogenic exposure ages have been used to quantify both the ice retreat and thinning of the west Greenland Ice Sheet in 3 transects from the coast to the present ice margin. Preliminary results (n=47) indicate initial deglaciation of coastal areas around 11 ka in concert with existing radiocarbon chronology, followed by a rapid retreat from the outer coast to the present ice margin around 10 ka. Boulder samples from the highest peaks demonstrate that the ice was warm-based whereas bedrock samples often contain an inherited signal. These results may have implications for other studies in Greenland, which have inferred thin LGM ice based on 10Be ages of bedrock samples. The threshold lakes are used to record episodes when the ice sheet was close-to-the present extent, represented by beds of clastic sediments whereas gyttja-deposition reflects periods when the glacier was behind the threshold, and no glacial meltwater input. Our results demonstrates that following the initial deglaciation the ice margin remained close to the present ice margin until around 7 cal. ka BP before it retreated behind the present extent during the Holocene Thermal Maximum (HTM). Here it remained until the Little Ice Age (LIA) where it readvanced to the present position around 0.5 cal. ka BP. Our results correspond to other recent findings from south and west Greenland that show that the ice sheet first began to retreat behind the present ice margin around 7 cal. ka BP. However, it differs from the other areas because the ice sheet first reappears at the present ice position during the LIA (i.e. no Neoglacial advance) and this suggest that the ice sheet in this area may have been more retracted and probably more sensitive to climate change than other areas in south and west Greenland.
AB - In this study, we use a combination of 10Be exposure ages and threshold lakes to constrain the ice sheet history in Godthåbs- and Buksefjorden, west Greenland (63-64°N) during the Holocene. The 10Be cosmogenic exposure ages have been used to quantify both the ice retreat and thinning of the west Greenland Ice Sheet in 3 transects from the coast to the present ice margin. Preliminary results (n=47) indicate initial deglaciation of coastal areas around 11 ka in concert with existing radiocarbon chronology, followed by a rapid retreat from the outer coast to the present ice margin around 10 ka. Boulder samples from the highest peaks demonstrate that the ice was warm-based whereas bedrock samples often contain an inherited signal. These results may have implications for other studies in Greenland, which have inferred thin LGM ice based on 10Be ages of bedrock samples. The threshold lakes are used to record episodes when the ice sheet was close-to-the present extent, represented by beds of clastic sediments whereas gyttja-deposition reflects periods when the glacier was behind the threshold, and no glacial meltwater input. Our results demonstrates that following the initial deglaciation the ice margin remained close to the present ice margin until around 7 cal. ka BP before it retreated behind the present extent during the Holocene Thermal Maximum (HTM). Here it remained until the Little Ice Age (LIA) where it readvanced to the present position around 0.5 cal. ka BP. Our results correspond to other recent findings from south and west Greenland that show that the ice sheet first began to retreat behind the present ice margin around 7 cal. ka BP. However, it differs from the other areas because the ice sheet first reappears at the present ice position during the LIA (i.e. no Neoglacial advance) and this suggest that the ice sheet in this area may have been more retracted and probably more sensitive to climate change than other areas in south and west Greenland.
KW - [0726] CRYOSPHERE / Ice sheets
KW - [1105] GEOCHRONOLOGY / Quaternary geochronology
KW - [1150] GEOCHRONOLOGY / Cosmogenic-nuclide exposure dating
KW - [1621] GLOBAL CHANGE / Cryospheric change
M3 - Conference abstract for conference
ER -
ID: 48849081