RAPID CHANGES IN OCEAN SURFACE WATER CONDITIONS AND CONTINENTAL PALEOCLIMATE DURING THE LAST 50 KYR OFF SOUTHERN CHILE BASED ON ODP SITE 1233

With average sedimentation-rates of 1 to 1.5 m/kyr during the last 50 kyr, marine sediments recovered at Ocean Drilling Project (ODP) Site 1233 (drilled during Leg 202 at the southern Chilean continental margin) provide an outstanding potential for unprecedented ultra high resolution reconstructions of surface ocean conditions and continental paleoclimates in the Southern Hemisphere mid-latitudes. Here we present records of changes in the terrigenous sediment input based on elemental composition data measured with 1 cm spacing (~decadal resolution) and compare these data to sea surface temperature (SST) and salinity (SSS) estimates (based on UK´ 37 paleotemperatures and planktic foraminifer oxygen isotopes). The iron content record shows large amplitude changes on millennial time-scales, particularly between ~20 and 50 kyr (calendar ages), with iron maxima correlating to glacier advances of the Patagonian ice-sheet suggesting that this record largely reflects ice-sheet variations during marine isotopes stages (MIS) 3. The ice-sheet extent changes are paralleled by paleo-SST changes in the order of ~2°C. The shape of the millennial-scale oscillations (particularly in the iron content record) strongly resembles Northern Hemisphere temperature changes as recorded in the GISP ice-core but the timing is different. Based on our preliminary 14C-AMS stratigraphy, ice-sheet retreats and the warming of surface waters significantly lead the Northern Hemisphere signal. The timing of the millennial changes is more similar to Antarctic temperature changes recorded in the Byrd ice-core. Termination 1 is characterized by a ~6°C SST warming which starts at ~18 kyr. Substantial transient SSS changes are documented during the termination and most likely reflect melt-water input from the waning Patagonian ice-sheet at this time.