HR: 0800h
AN: C11A-0073    [Abstracts]
TI: Modeling the Deposition of Deglaciation Moraines
AU: * Vacco, D
EM: dvacco@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802, United States
AU: Alley, R
EM: ralley@geosc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802, United States
AU: Pollard, D
EM: pollard@essc.psu.edu
AF: Pennsylvania State University, Department of Geosciences, University Park, PA 16802, United States
AB: Moraine ages figure prominently in reconstructions of the history of the Greenland ice sheet and of other ice masses, and in testing of hypotheses such as that of Denton et al. (2005, QSR) that north Atlantic millennial oscillations including the Younger Dryas were primarily wintertime events. We present a fast, coupled ice- flow/moraine-deposition model to aid in such hypothesis-testing. We find that not only ages and positions of moraines, but also number of moraines and their volumes, can help in interpretation. The model allows for multiple sediment-transport mechanisms and climate forcings, in a simple but flexible flowline configuration fast enough that inversions may be practical in the future. The temperature forcing for the model was the GISP2 ice core record spanning the time period between LGM and modern. We decoupled the orbital deglacial signal and the millennial-scale signal using a band-pass filter with cut-off at 10,000 years. We applied the ice core records as the forcing to the glacier-sediment model while systematically varying the strength of the millennial scale signal. Our results are examples of moraines deposited with varying degree of strength of millennial-scale signals, some of which show similarity to moraine sets observed around Greenland and the northern hemisphere.
DE: 0720 Glaciers
DE: 0776 Glaciology (1621, 1827, 1863)
DE: 0798 Modeling
DE: 1105 Quaternary geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
SC: Cryosphere [C]
MN: 2007 Fall Meeting