2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 8
Presentation Time: 10:15 AM


KELLY, Meredith A.1, HALL, Brenda L.2, LOWELL, Thomas V.3, SCHAEFER, Joerg M.1, DENTON, George H.2 and BROECKER, Wallace S.1, (1)Geochemistry, Lamont-Doherty Earth Observatory, 61 Rte. 9 West, PO Box 1000, Palisades, NY 10964, (2)Climate Change Institute and Department of Earth Sciences, University of Maine, Bryand Global Science Center, Orono, ME 04469, (3)Department of Geology, University of Cincinnati, 500 Geology /Physics, Cincinnati, OH 45221, meredith@ldeo.columbia.edu

The surface exposure dating method is applied to develop a chronology of mountain glaciation in the Scoresby Sund region of East Greenland (~72°N, 24°W). At least twenty 10Be dates of glacially transported boulders from atop moraines and kames indicate that valley glaciers likely existed during the last glacial maximum (LGM) and the last glacial-interglacial transition. Radiocarbon dates of shells from raised marine terraces deposited subsequent to deglaciation are minimum ages for the moraines. These radiocarbon dates provide rates of post-glacial isostatic uplift based upon terrace elevations which are important for an accurate determination of 10Be production rates.

Equilibrium line altitudes (ELAs) of former valley glaciers are estimated based on field evidence and map data. ELAs associated with former glacial extents are compared to the ELA from a historic glacial advance. The surface exposure dates, coupled with ELA depressions, enable a calculation of the temperature signals underlying the respective glacial advances and a comparison of these data with other paleoclimatic records.

Of particular interest is a comparison of paleotemperature records from mountain glaciers in East Greenland with paleotemperatures recorded by nearby Greenland ice cores, such as Renland and GISP2. Paleotemperature records from Greenland ice cores show a cooling during abrupt cold events within the last glacial period that is one order of magnitude greater than paleotemperatures determined from ELA depressions of mountain glaciers in mid- and high-latitude regions elsewhere. The data will rigorously test whether a similar discrepancy exists between paleotemperatures as recorded by Greenland ice cores and those derived from ELA depressions of mountain glaciers in East Greenland. The existence of such a discrepancy would suggest that Greenland ice cores and mountain glaciers recorded different climatic signals.