Planktic foraminiferal turnover across the Paleocene-Eocene transition in the Bay of Biscay, North Atlantic

The benthic foraminiferal extinction event (BFEE) and Sr3C excursion was accompanied by a planktic foraminiferal turnover marked by an influx of warm water species (Morozovella and Acarinina), a decrease in cooler water species (Subbotina), a sudden short-term increase in low oxygen tolerant taxa (Chiloguembelina), and no significant species extinctions.

These faunal changes suggest climatic warming, expansion of the oxygen minimum zone, and a well stratified ocean water column. Oxygen isotope data of the surface dweller M. subbotina suggest climate warming beginning with a gradual 0.5‰ decrease in delta180 in the 175 cm preceding the benthic foraminiferal extinction event followed by a sudden decrease of 1‰ (4°C) at the BFEE. The delta13C excursion occurred over 27 cm of sediment and, assuming constant sediment accumulation rates, represents a maximum of 23 ka.