Jp. Kennett et Bl. Ingram, A 20,000 YEAR RECORD OF OCEAN CIRCULATION AND CLIMATE-CHANGE FROM THESANTA-BARBARA BASIN, Nature, 377(6549), 1995, pp. 510-514
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.