Eustatic estimates from the backstripping of Oligocene sections are compared quantitatively with delta(18)O data. Each of the nine Oligocene delta(18)O events (maxima) identified in previous studies correlates with a stratigraphically determined sea-level lowstand. Oxygen isotopic records from planktonic foraminifers from western equatorial Atlantic Ocean Drilling Program (ODP) Site 929 indicate an isotopic increase of 0.16parts per thousand per 10 in decrease in the depth of the ocean (apparent sea level, ASL). Amplitudes of ASL change also correlate with moderate- and high-resolution benthic foraminiferal delta(18)O records from ODP Sites 803 (western tropical Pacific) and 929 and from Deep Sea Drilling Project (DSDP) Site 522 (South Atlantic Ocean), with an isotopic change of 0.22parts per thousand per 10 m of ASL change (r(2) = 0.807 and 0.960, respectively), and with records from ODP Site 689 (Southern Ocean; 0.13parts per thousand per 10 m of ASL change; r(2) = 0.704). This correlation suggests that Southern Ocean deep-water temperature changes were smaller than tropical sea-surface temperature changes between million year-scale glacials and interglacials. It also suggests that the deep-sea Southern Ocean records may provide the best means to calibrate sea level to oxygen isotopes.
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