HR: 0800h
AN: PP51F-1365    [Abstracts]
TI: Alkenone Sea-surface Temperature Variations in the Southeast Pacific Ocean Inferred from a High-Resolution Record of the past 200,000 Years (ODP Site 1234)
AU: * Chen, M
EM: mtchen@mail.ntou.edu.tw
AU: Huang, C
EM: ggp997@ms21.hinet.net
AB: High sedimentation rate records with millennial to centennial resolution were recovered from ODP Site 1234 in the southeast Pacific. SST reconstructions by using alkenone unsaturation indices measured from the sediments recovered from this site allow assessment of climate variability pattern in the surface ocean of the southeastern Pacific. Site 1234 SST records also provide opportunity to establish a high-resolution record that is sensitive to eastern Pacific climate, and allow a comparison with a SST record from a more southern (ODP Site 1233) near the glacial extension of Patagonian Ice Sheet in southern Chile. The record from Site 1234 can be compare further with a western Pacific record (MD972151) over the last two glacial-interglacial cycles and be used to identify any basin-scale type of climate variability pattern in the Pacific. In this study, we present (~10cm mcd sampling intervals, ~200 years resolution) alkenone SST reconstruction that covers the past ~200,000 years. Based on our preliminary results, the SST record from Site 1234 reveals large oscillations from ~17-11›FXC and patterns of high frequency changes which open a room for further correlations with Greenland and Antarctic ice cores. Large amplitude oscillations in SSTs are also observed from the MIS 5 interval of the record and appear to parallel to the variations of benthic oxygen isotopes measured from the same core. A long-term trend of alkenone concentration decreases is clearly observed from MIS 5 to the present, suggesting that at this site calcareous productivity was decreased or siliceous productivity / terrestrial sediment supply was increased since MIS 5. Accurate chronological controls by using AMS 14C, paleomagnetic and oxygen isotope stratigraphies will provide opportunity to assess the timing of these climatic events into a global framework.
DE: 9355 Pacific Ocean
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 1055 Organic geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting