Geochemical and Sedimentological Constraints on the Aerial Extent of the Southern Greenland Ice Sheet

Elizabeth Colville
Department of Geology & Geophysics, University of Wisconsin-Madison, 53706, USA; [email protected]

During the penultimate interglacial period (~130 – 120 kyr BP), sea level was up to 6 meters higher than present under enhanced boreal summer insolation, indicating a greatly diminished Greenland and/or Antarctic Ice Sheet. Southern Greenland contains three distinct geologic terranes with unique geochemical signatures, changes in geochemical and sedimentological data in ocean sediments off the coast of southern Greenland can help constrain the aerial extent of the Greenland Ice Sheet and thus its contribution to sea level during the penultimate interglacial and other periods of climatic warming.

A sedimentological and geochemical dataset from ocean core MD99-2227, located on the Eirik Drift off the coast of southern Greenland, is being compiled. Preliminary data indicate a ~25 kyr period of terrestrial sediment input to the Eirik Drift during the penultimate deglaciation and subsequent interglacial compared to only ~5 kyr of enhanced silt input during the last and subsequent Holocene deglaciations. This record suggests a greatly diminished southern Greenland Ice Sheet during the penultimate interglacial relative to present. The sedimentological data are in agreement with earlier Ti, Fe and magnetic grain size records from the Eirik Drift and confirm that these proxies are recording changes in fine-grain sediment input rather than ice rafting or variability in the Western Boundary Under Current strength.

During summer 2008, suspended load sediment was collected from streams draining the three isotopically different geologic terranes of southern Greenland. Geochemical data obtained from these samples will provide end-members for the geochemical data from MD99-2227.

AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid