HR: 0800h
AN: C11A-0070    [Abstracts]
TI: Late-Glacial and Holocene Relative Sea-Level Change, Scoresby Sund, East Greenland
AU: * Hall, B
EM: BrendaH@maine.edu
AF: Department of Earth Sciences and the Climate Change Institute, University of Maine, Orono, ME 04469, United States
AU: Baroni, C
EM: baroni@dst.unipi.it
AF: Dipartimento di Scienze della Terra, Universita di Pisa, Pisa, 56126, Italy
AU: Denton, G
EM: gdenton@maine.edu
AF: Department of Earth Sciences and the Climate Change Institute, University of Maine, Orono, ME 04469, United States
AU: Kelly, M
EM: meredith@ldeo.columbia.edu
AF: Department of Geochemistry, Lamont-Doherty Earth Observatory, Palisades, NY 10964, United States
AU: Lowell, T
EM: thomas.lowell@uc.edu
AF: Department of Geology, University of Cincinnati, Cincinnati, OH 45221, United States
AB: The age of the Milne Land Stade (MLS) moraines in East Greenland is key for testing the hypothesis that abrupt cooling events seen in Greenland ice cores are characterized by extreme seasonality. In recent papers, the moraines have been assumed to be of Younger Dryas age, allowing direct comparison of snowline lowering estimates with coeval temperature depressions from the nearby ice cores. It is a mismatch of as much as 10 degrees C between these two climate proxies that led to the idea of extreme seasonality. Thus, accurately determining the age of the moraines is a prerequisite to testing this hypothesis. In the Scoresby Sund region, retreat from the MLS moraines was accompanied by marine inundation and isostatic rebound. Here, we present more than 150 radiocarbon dates of shells in raised beaches and deltas from Kjove Land and nearby Schuchert Dal that formed after deglaciation from adjacent MLS moraines. Together, these samples are the basis for two curves, each of which shows very high rates of relative sea-level change typical of recently deglaciated regions. The curves are similar, with both indicating total uplift (including areas now drowned by rising sea level) of slightly less than 200 m. The marine limit (134 m) dates to 12,200 cal yr B.P. We suggest that this is a close minimum age for moraine formation and indicates that the outer MLS moraines likely date to earliest Younger Dryas time. The younger, inner moraine set grades to a former sea level, now at 101 m elevation, and dates to 10,600-10,900 cal yr B.P. The Younger Dryas age for the older set is consistent with the idea that there was extreme seasonality in Greenland during late-glacial time.
DE: 0726 Ice sheets
DE: 1105 Quaternary geochronology
DE: 1605 Abrupt/rapid climate change (4901, 8408)
SC: Cryosphere [C]
MN: 2007 Fall Meeting