Abstract
We have constructed a relatively high resolution (5–10 kyr) Globigerina bulloides stable isotope record from Ocean Drilling Program Site 1088 (South Atlantic sector of the Southern Ocean). Together with the two published records from the high latitudes of the Southern Hemisphere that each span at least a portion of this interval of time, we begin to assemble a spatial picture of sea surface hydrography during the late Miocene early Pliocene climate transition (~ 8–3 Ma). We hypothesize that meridional movements in the frontal zones (Polar Front and Subtropical Convergence) with their impact on hydrographic gradients would be evident in temporal changes in the planktonic foraminiferal stable isotopic gradients among the sites. Our results indicate that there were no large changes in δ 18O gradients during the interval of study. Relatively small changes such as a gradual warming of about 3–4 °C at Site 1088 during the late Miocene fall well within the realm of modern ocean seasonality in this region. The early Pliocene δ 18O records largely parallel the global decrease defined by benthic foraminifera in the deep Pacific suggesting no amplified warming of surface waters in the Southern Ocean. The planktic δ 13C records vary positively with the δ 18O records both in the long term trend as well as on the scale of individual data points. We believe that this association reflects primarily reduced nutrient utilization during warmer intervals although a small component of the signal would also be consistent with reduced carbon isotope fractionation during air–sea gas exchange during relatively warmer conditions. If correct, this argument would have implications for carbon cycling during the early Pliocene and would support scenarios of elevated CO 2 levels.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.