HR: 14:40h
AN: PP43C-05    [Abstracts]
TI: Integrating Antarctic Near Shore and Deep Sea Records of Warm Interglacials
AU: * Scherer, R P
EM: reed@geol.niu.edu
AF: Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115 United States
AB: The best way to accurately interpret polar ice sheet history is to make every effort to recover and date continental margin deposits proximal to the ice sheets, and confidently correlate these records with deep-sea cores. Deep-sea oxygen isotope records provide the best available archive of global ice volume, but they say nothing directly about specific changes in ice sheet configuration. Although geologic records along the margins of polar landmasses are rare, and those that exist are highly incomplete, they record climatic events in the global end-member environment, demonstrating the sensitivity of the system to climate change. Pelagic waters impinge far south along the Victoria Land coastline of Antarctica in McMurdo Sound. Increasing the southward encroachment of warm waters during interglacials affects moisture flux, sub-ice shelf circulation, and sea ice conditions, as well as surface water temperatures. These factors affect, in complex ways, ice shelf stability and, ultimately, marine (West Antarctic) and continental (East Antarctic) ice sheet configurations. The CIROS-2 drill core includes precisely dated and unequivocal evidence of pelagic waters in the near shore zone during the mid Pliocene. Likewise, the Cape Roberts Project (CRP-1) recovered a 2m thick carbonate-rich unit, unequivocally dated as MIS-31 (1.07 Ma) that indicates significantly elevated surface water temperatures and minimal sea ice. The warmest part of MIS-31 coincides with a paleomagnetic reversal (the base of the Jaramillo at 1.072 Ma), which offers an unprecedented opportunity for precise correlation with deep-sea cores, and offers the possibility of precise interhemispheric comparison of high latitude surface ocean conditions. Other marine interglacial deposits, notably MIS-11 and MIS-5e, have been recognized on the Antarctic margin, but dating is often not as precise as we strive for. High quality Pliocene through Holocene core is anticipated from the McMurdo Ice Shelf site of the upcoming ANDRILL program (to be drilled in late 2006). A key goal of this site will be to recover records of unusually warm interglacial events, allowing integration of proximal and distal evidence of the sensitivity of Antarctica and its ice sheets to climate change.
UR: http://andrill.org
DE: 0798 Modeling
DE: 1621 Cryospheric change (0776)
DE: 4936 Interglacial
DE: 4938 Interhemispheric phasing
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005