The PI's will study the variation of stable carbon and oxygen isotope contents in planktonic and benthic foraminifera from two Eocene/Oligocene sequences (DSDP core 522) in the South Atlantic and one core (DSDP core 748) in the southern Indian Ocean to determine if early Oligocene ice-sheets on Antarctica displayed the same waxing and waning as seen during the Neogene. If so, was the signal the same or different in amplitude/frequency; i.e. does tyhe earliest Oligocene record display Milankovitch rhthyms? This study is facilitated by the improvement in Paleogene stratigraphy, particularly chemo-and- magneto-stratigraphies.
