HR: 13:55h
AN: C13A-02    [Abstracts]
TI: Cosmogenic Exposure Ages From Northeast Greenland Constrain the Extent of the Greenland Ice Sheet During the Last Glacial Maximum
AU: * Håkansson, L
EM: lena.hakansson@geol.lu.se
AF: Department of Geology, Lund University, Sölvegatan 12, Lund, 22362, Sweden
AU: * Håkansson, L
EM: lena.hakansson@geol.lu.se
AF: Department of Geology, University at Buffalo, 876 NSC, Buffalo, NY 14260, United States
AU: Briner, J P
EM: jbriner@uffalo.edu
AF: Department of Geology, University at Buffalo, 876 NSC, Buffalo, NY 14260, United States
AU: Alexanderson, H
EM: Helena.Alexanderson@natgeo.su.se
AF: Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, 10691, Sweden
AU: Aldahan, A
EM: Ala.Aldahan@geo.uu.se
AF: Department of Earth Sciences, Uppsala University, Villavägen 16, Uppsala, 75236, Sweden
AU: Possnert, G
EM: Goran.Possnert@Angstom.uu.se
AF: Tandem Laboratory, Uppsala University, Uppsala, 75121, Sweden
AB: Traditional reconstructions have suggested two distinctly different ice sheet regimes along the East Greenland continental margin during the Last Glacial Maximum (LGM); ice to the shelf break south of Scoresby Sund and ice extending no further than to the inner shelf at and north of Scoresby Sund. We report on new ¹⁰Be-ages from erratic boulders perched at 250 m a.s.l. on the Kap Brewster peninsula at the mouth of Scoresby Sund. The average ages, calculated with and without an assumed maximum erosion rate of 1 cm/ka indicate c.17 ka and c.15 ka, respectively. These ages overlap a period of increased sediment input to the Scoresby Sund fan between 19 and 15 ka ago. Such results suggest that glacier ice reached at least 250 m asl at the mouth of Scoresby Sund and advanced onto the outer shelf during the LGM. It further implies that sliding ice in the fjord-trough was buttressed by cold-based ice on Jameson Land, which has hitherto been regarded as ice-free during the LGM. The results presented above provide additional evidence to the presumed hypothesis that indicates LGM ice had extended onto the outer shelf in northeast Greenland. Accordingly ¹⁰Be and ²⁶Al ages from Jameson Land and areas north thereof, relevant in this context, are pending.
DE: 0720 Glaciers
DE: 0726 Ice sheets
SC: Cryosphere [C]
MN: 2007 Fall Meeting