High Resolution UK37 Alkenone Paleothermometry at Bermuda Rise: The Last Interglacial to the Little Ice Age

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Abstract ATM-9610128 Lehman, Scott J. University of Colorado Title: High Resolution UK37 Alkenone Paleothermometry at Bermuda Rise: The Last Interglacial to the Little Ice Age Subtropical sea surface temperature (SST) is an important climate boundary condition within much of the North Atlantic basin. It is not known, however, whether sub-polar millennial- and century- scale SST changes also affected the subtropical gyre, and to what degree such changes were connected with variations in the rate of formation of North Atlantic Deep Water (NADW). Recently recovered long cores, by the Marion Dufresne, provide an unparalleled opportunity to study highly resolved proxy records of SST and NADW variations. Work supported by this grant will establish a time series of SST at 50-yr to 100-yr sample spacing for the past 150 kyr in sediments of the Bermuda Rise using the alkenone paleo-temperature estimation technique. Similar measurements made in a pilot study of the last 15 kyr provide evidence of large swings in SST during the last deglaciation. This is consistent with SST estimates from foraminiferal assemblage data. The pilot results demonstrate that the proposed studies are likely to yield a high-amplitude signal of SST variations for the North Atlantic subtropical gyre. The fidelity and geographic representativeness of the Bermuda Rise results can be cross-checked at key intervals by analysis of a second high deposition-rate core from Blake-Bahama Outer Ridge. Combining this work with other proxy studies will produce paired proxy records of SST and NADW variation and will allow the evaluation of the role of the ocean thermohaline circulation in climate changes occurring on these timescales.