LATE QUATERNARY CARBON AND OXYGEN ISOTOPES USING ORBULINA UNIVERSA, OCEAN DRILLING PROGRAM LEG 165 SITE 1002C, CARIACO BASIN, CARIBBEAN SEA
Extensive stable isotope work has been done at Site 1002c with oxygen isotopes (δ18O), using both benthic and planktonic foraminifers. Studies of carbon isotopes (δ13C) obtained from planktonic foraminifers remain incomplete. The mixed layer dwelling planktonic foraminifer, Orbulina universa, has been selected for the stable isotope measurements in this study.
Fresh water runoff from continental sources is enriched in 16O. Previous studies of δ18O at ODP site 1002 indicate a strong local influence on the isotopic record when compared to global ice volume records of δ18O from outside the Cariaco Basin. By utilizing the δ13C record of Orbulina universa, an understanding of local productivity in response to cycles of localized increased ocean freshening within the basin from river runoff can be made. It is expected that the cycles of freshwater fluctuations will be detected in the δ13C and δ18O records at ODP site 1002c. This will provide an understanding of the interactions between local biotic productivity and ocean basin freshening of wet and dry periods in the Cariaco Basin and be used as a modern analogue for future deep time studies.