Millenial-Scale Climate and Ocean Changes in the Western North Atlantic

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AbstractThis proposal requests support for a study to combine data from many cores from the Blake-Bahama Outer Ridges and the adjacent slope, within the intermediate (~l500m) to deep (~4700m) ocean, in order to assemble a paleohydrography along the western boundary of the Atlantic. This, combined with nearby data from the depth range 400m to 1500m at Little Bahama Bank, will form the most detailed and extensive paleohydrography for any ocean basin. For this project, carbon isotopes in benthic foraminifera will be the main tracer for paleonutrients, and the age difference between paired benthic and planktonic radiocarbon analyses will be a ventilation tracer. These tracers will be applied to the Last Glacial Maximum (LGM) level in the core collection to determine the extent of frontal changes between deep and intermediate depth water masses They will also be applied to the millennial-scale event of about 11,000 14C yrs ago (known as the Younger Dryas) to compare millennial-scale with orbital-scale (LGM) hydrographic changes. Finally, the extent of millennial scale hydrographic changes will be evaluated during isotope Stage 3 (~30 to 60 kyr before present) when climate cycled rapidly and repeatedly.