Eocene-Oligocene faunal turnover in planktic foraminifera, and Antarctic glaciation

Stable isotope records and glacio-marine sediments from high latitude southern ocean ODP Legs 113 and 119 provide evidence of major glaciation on East Antarctica during the late middle to late Eocene and early Oligocene with glaciation persisting into the late Oligocene. Carbon and oxygen isotopic gradients for planktonic and benthic foraminiferal species reflect decreasing surface productivity and thermal stratification during this time. The remarkably close correspondence between these stable isotope records and planktonic foraminiferal turnovers strongly suggests that changes in climate and productivity were the primary driving forces behind the gradual decline and eventual extinction of the Eocene planktonic foraminiferal fauna. -from Authors