Calibration between eustatic estimates from backstripping and oxygen isotopic records for the Oligocene
- 1Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA
- 2Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA
- 3Department of Geosciences, Western Michigan University, Kalamazoo, Michigan 49008, USA
- 4Department of Geological Sciences, Wright Labs, Rutgers University, Piscataway, New Jersey 08854, USA
Abstract
Eustatic estimates from the backstripping of Oligocene sections are compared quantitatively with δ18O data. Each of the nine Oligocene δ18O 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 0.16‰ per 10 m decrease in the depth of the ocean (apparent sea level, ASL). Amplitudes of ASL change also correlate with moderate- and high-resolution benthic for a min i fer al δ18O 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 0.22‰ per 10 m of ASL change (r2 = 0.807 and 0.960, respectively), and with records from ODP Site 689 (Southern Ocean; 0.13‰ per 10 m of ASL change; r2 = 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.
Footnotes
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- Accepted June 20, 2002.
- Received March 15, 2002.
- Revision received June 17, 2002.
- Geological Society of America
