Late Quaternary History of the Western and East-Central Ross Sea, Antarctica: A Contribution to the West Antarctic Ice Sheet Initiative

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OPP 9614287 Andrews OPP 9615046 Leventer Abstract The late Quaternary extent and pattern of retreat of the West Antarctic Ice Sheet is an important control on interpretation of ice core records from the region and it has important ramification regarding the global water budget (in sea level terms), the timing of meltwater contributions to the ocean, and the synchrony (or lack thereof) between events in the Northern and Southern Hemispheres. This award supports continued research on the chronology of ice retreat from the western Ross Sea and an extension of areal coverage for this research to include the east- central Ross Sea. The study will use a series of piston, Kasten, and grab samples from research cruises in 1994 and 1995 on the RVIB N.B. Palmer by researchers from Rice University, University of Colorado, Boulder, and Hamilton College. Various physical and biological parameters of the cores will be used to map changes in the environments over time with a concentration on sediment properties, foraminifera, and diatoms. At this time, ninety-two carbon-14 dates (plus 18 pending dates, all based on accelerator- mass-spectrometry) have been obtained from cores collected prior to 1994 and from the 1994 and 1995 cruises by the research groups at Hamilton College and the University of Colorado, Boulder. Emphasis will be placed on obtaining additional radiocarbon dates supplemented by several other chronological methods including: sources and ages of volcanic ashes, uranium-series dating of solitary corals, and amino acid racemization. The three major research questions are: 1) What was the position of the grounding line during the Last Glacial Maximum from the western to east-central Ross Sea and what was the timing of retreat from this limit, was it synchronous across the region, and what was the rate of retreat ? 2) Is there evidence from the history of carbonate accumulation on the outer shelf banks, and from cores on the slope of the Ross Sea that th e ice was grounded on the shelf break at some time prior to marine isotope stage (MIS) 2, possibly at MIS 4 (Goodwin, person. commun. 1996)? 3) What are the paleoenvironments in the areas of the Ross Sea at the millenial/century time-scales during the latest Pleistocene and the Holocene? In particular, what is the history of changes in surface water productivity and sea ice extent?