HR: 1340h
AN: U33A-0011    [Abstracts]
TI: Preliminary ¹⁰Be Chronology for the Last Deglaciation of the Western Margin of the Greenland Ice Sheet
AU: Rinterknecht, V R
EM: vincent@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 route 9W/ P.O. Box 1000, Palisades, NY 10964 United States
AU: * Gorokhovich, Y
EM: ygorokho@ciesin.columbia.edu
AF: Center for International Earth Science Information Network, 61 route 9W/ P.O. Box 1000, Palisades, NY 10964 United States
AU: Schaefer, J M
EM: schaefer@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 route 9W/ P.O. Box 1000, Palisades, NY 10964 United States
AU: Comer, G C
EM: gcomer@gcionline.com
AF: GCI, GCI, Waukesha, WI 53186 United States
AU: Broecker, W S
EM: broecker@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 route 9W/ P.O. Box 1000, Palisades, NY 10964 United States
AB: Paleoclimatic trends in the polar region have become increasingly important following the recognition of a probable polar amplification to global warming. High latitude feedback mechanisms play an important role in the climate system, but in the absence of long term meteorological records, natural climate variability and feedback mechanisms remain poorly understood. Arctic areas are rich in glacial features of all sizes and their deposition time and mode contain one of the few continuous archives for deciphering past climate variability in present-day arid continental subarctic areas. On the largest ice free land of Western Greenland we identified a 175 km long eastward transect from the town of Sisimiut on the coast to the Isunguata Sermia Glacier ice margin. In addition, one of the glacial valleys was selected for the large-scale dating and terrain mapping. In this area, ice cover extended beyond the present day coastline during the larger parts of the Sisimiut glaciation of Late Wisconsinan-Weichselian age. During the course of deglaciation, the Inland Ice margin progressively recessed about 175 km east in the study area. Frequent halts or re-advances interrupted the retreat and formed extensive moraine systems: Sisimiut (associated to the Younger Dryas cold event), Taserqat, Sarfartôq-Advedtleq, Fjord, Umivit-Keglen, and Orkendalen (close to the modern ice margin). These moraine systems were identified 50 km south of Sisimiut, however the dating and the mapping are poor to inexistent in our study area. We present here the first results of surface exposure dating and terrain mapping for this previously unexplored area. The first surface exposure ages constrain a preliminary chronology for the last deglaciation of the western margin of the Greenland Ice Sheet. Satellite imagery complemented with our ground measurements and observations define the geomorphological settings that allow us to reconstruct the last deglaciation pattern of the ice sheet margin as well as its thickness variation through the last deglaciation.
DE: 0726 Ice sheets
DE: 1105 Quaternary geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 9315 Arctic region (0718, 4207)
SC: Union [U]
MN: Fall Meeting 2005