Late quaternary paleoceanography of the Atlantic Ocean: foraminiferal faunal and stable-isotopic evidence
The timing, frequencies, and rates of change of tropical Atlantic climates are studied on a glacial/interglacial scale, using foraminferal faunal abundance and stable isotopic data to estimate temperatures, ice volumes, and water mass properties of the surface and deep ocean. Oxygen-isotope and radiocarbon data constrain the timing of the last deglacial transition (Termination 1) to between 14,000 and 6000 yr BP. Deglaciation was not a continuous process, but may have occurred in steps from 14,000 to 12,000 yr BP, 10,000 to 8000 yr BP, and 7000 to 6000 yr BP. Changes in the ..delta../sup 18/O of glacier ice may induce a lag of the marine ..delta../sup 18/O record behind ice volume of 1000 to 3000 years. Temperature changes estimated by foraminferal transfer functions were not detected in down-core planktonic foraminferal ..delta../sup 18/O data. Hemispheric symmetry of glacial cooling may reflect linkage to high latitude climate changes via trade wind intensities and/or directions. During deglaciation, the North Atlantic was relatively cold, the South Atlantic was relatively warm, and equatorial seasonal contrast was low. This may reflect reduction of northward cross-equatorial heat transport in the ocean, and possible monsoonal effects. Climate changes also extend to the deep ocean. At mid-depths of the tropical Atlantic, minimum Atlantic-Pacific ..delta../sup 13/C difference occurring on average during deglaciation (with a strong 23,000-yr precession cycle) suggests reduced formation of a warm component of NADW during deglaciation. A deeper sites in the North Atlantic, reduced ventilation of deep basins during glacial maxima is linked to surface-water variability of the subpolar North Atlantic.
- Research Organization:
- Columbia Univ., New York (USA)
- OSTI ID:
- 6827258
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580500* -- Oceanography-- (1980-1989)
AGE ESTIMATION
ATLANTIC OCEAN
CARBON 13
CARBON ISOTOPES
CENOZOIC ERA
EARTH PLANET
ENERGY TRANSFER
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
GLACIERS
HEAT TRANSFER
HYDROGEN COMPOUNDS
ICE
ISOTOPE DATING
ISOTOPES
LIGHT NUCLEI
NORTHERN HEMISPHERE
NUCLEI
OCEANOGRAPHY
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PALEOCLIMATOLOGY
PALEONTOLOGY
PLANETS
QUATERNARY PERIOD
SEA BED
SEAS
SEAWATER
SOUTHERN HEMISPHERE
STABLE ISOTOPES
SURFACE WATERS
TEMPERATURE MEASUREMENT
TROPICAL REGIONS
VARIATIONS
VOLUME
WATER