A 20,000 YEAR RECORD OF OCEAN CIRCULATION AND CLIMATE-CHANGE FROM THESANTA-BARBARA BASIN

MUCH of the evidence for climate-driven fluctuations in ocean circulat ion during the past 20,000 years has come from studies of the North At lantic region(1-6). The extent to which such interactions have occurre d in other ocean basins, and any associated teleconnections between ba sins, is poorly understood. Here we present high-resolution palaeoclim ate and palaeoceanographic records from a 20,000-year sedimentary sequ ence from the Santa Barbara basin, on the eastern margin of the North Pacific Ocean. The sequence shows oscillations of the benthic environm ent between low-oxygen conditions (laminated sediments) during periods of warm climate, and higher-oxygen conditions (non-laminated, bioturb ated sediments) during cool intervals. Age differences between coexist ing benthic and planktonic foraminifers indicate climate-related chang es in the age and source--and, hence, oxygen content--of basin bottom waters. Relatively young bottom waters are associated with the cooler intervals and are considered to reflect high proportions of intermedia te waters derived from proximal sources. Conversely, older bottom wate rs are associated with the warmer intervals and were derived from more distal sources. These climate-driven variations in ocean circulation appear to be synchronous with the main ocean-climate fluctuations in t he North Atlantic region(1-6), suggesting that a tight coupling mechan ism operates between the two basins.