Christina R. Riesselman1, Robert B. Dunbar1, David A. Mucciarone1, and Saya S. Kitasei2. (1) Department of Geological and Environmental Sciences, Stanford University, 325 Braun Hall, Stanford, CA 94305, (2) Earth Systems Program, Stanford University, School of Earth Sciences, Mitchell Building, Room 138, Stanford, CA 94305
The rapid enrichment of benthic d18O in the early Oligocene (~33.6 Ma) has been taken to imply the first appearance of large ice sheets on Antarctica. This transition is accompanied by a reorganization of the global carbon cycle, identified by a d13C enrichment that slightly lags the glacially-mediated d18O transition. Here, we present a new record of the early Oligocene climate transition from the subtropical South Atlantic Ocean. To investigate climatic and carbon cycle variability in the transition from the early Paleogene “greenhouse” into the Oligocene “icehouse” world, we have developed carbonate content, coarse fraction, and benthic foraminiferal carbon and oxygen stable isotope records for the earliest Oligocene at Ocean Drilling Program Site 1263. These records represent the highest-resolution reconstruction of the Eocene/Oligocene from the Atlantic basin to date, and provide us with a unique opportunity to investigate the fine-scale interplay of glaciation and the global carbon cycle.
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