Ocean export production and foraminiferal stable isotopes in the Antarctic Southern Ocean across the mid-Pleistocene transition

Tuesday, 16 December 2014
Adam Patrik Hasenfratz1, Alfredo Martinez-Garcia1, Sam Jaccard2, David A Hodell3, Derek Vance1, Stefano M Bernasconi1, Mervyn Greaves3 and Gerald Hermann Haug1, (1)ETH Swiss Federal Institute of Technology Zurich, Zurich, Switzerland, (2)University of Bern, Bern, Switzerland, (3)University of Cambridge, Cambridge, United Kingdom
Changes in buoyancy forcing in the Antarctic Zone (AZ) of the Southern Ocean are believed to play an instrumental role in modulating atmospheric CO2 concentrations during glacial cycles by regulating the transfer of carbon between the ocean interior and the atmosphere. Indeed, a million-year-spanning high-resolution excess Barium record from the AZ of the South Atlantic (ODP 1094), which traces changes in export production, shows decreased export production during cold periods suggesting decreased overturning. Here, we extend this AZ export production record back to 1.6 Myr. In addition, we present new carbon and oxygen isotope records of benthic and planktic foraminifera from the same site, complemented by Mg/Ca measurements in some intervals. The interpretation of these new data in the context of other South Atlantic records contributes to a better understanding of Southern Ocean hydrography and its role in modulating glacial/interglacial cycles over the past 1.6 Myr.