C51B-0690
New constraints on the deglaciation chronology of the southeastern margin of the Greenland Ice Sheet

Friday, 18 December 2015
Poster Hall (Moscone South)
Laura Levy1, Nicolaj K Larsen2, Kurt Henrik Kjaer3, Anders A Bjork4, Kristian K Kjeldsen4, Svend Funder5, Meredith A Kelly6, Jennifer A Howley7 and Susan R H Zimmerman8, (1)Aarhus University, Department of Geoscience, Aarhus, Denmark, (2)Aarhus University, Aarhus, Denmark, (3)Natural History Museum, Copenhagen, Denmark, (4)Natural History Museum of Denmark, Copenhagen, Denmark, (5)Geological Museum – University of Copenhagen, Copenhagen, Denmark, (6)Dartmouth College, Department of Earth Sciences, Hanover, NH, United States, (7)Dartmouth College, Hanover, NH, United States, (8)Lawrence Livermore National Laboratory, Livermore, CA, United States
Abstract:
The Greenland Ice Sheet (GrIS) is responding rapidly to climate change. Marine terminating outlet glaciers that drain the GrIS have responded especially sensitively to present-day climate change by accelerating, thinning and retreating. In southeastern Greenland several outlet glaciers are undergoing rapid changes in mass balance and ice dynamics. To improve our understanding of the future, long-term response of these marine-terminating outlet glaciers to climate change, we focus on the response of three outlet glaciers to climate change since the Last Glacial Maximum.

The timing and rates of late-glacial and early Holocene deglaciation of the southeastern sector of the GrIS are relatively unconstrained due to the inaccessibility of the region. Using a helicopter and a sailboat, we collected samples for 10Be surface exposure dating from three fjords in southeastern Greenland: Skjoldungen (63.4N), Uvtorsiutit (62.7N), and Lindenow (60.6N). These fjords drain marine terminating glaciers of the GrIS. Here we present 18 new 10Be ages from ~50 km long transects along these fjords that mark the timing of deglaciation from the outer coast inland to the present-day GrIS margin.

Together with previously constrained deglaciation chronologies from Bernstorffs, Sermilik, and Kangerdlussuaq fjords in southeastern Greenland, these new chronologies offer insight into the late-glacial and early Holocene dynamics of the southeastern GrIS outlet glaciers. We compare the timing and rate of deglaciation in southeastern Greenland to climate records from the region to examine the mechanisms that drove deglaciation during late-glacial and early Holocene time. These new 10Be ages provide a longer-term perspective of marine terminating outlet glacier fluctuations in southeastern Greenland and can be used to model the ice sheet’s response to late-glacial and early Holocene climate changes.