Planktic foraminiferal turnover across the Paleocene-Eocene transition at DSDP Site 401, Bay of Biscay, North Atlantic

Alfonso Pardo, Gerta Keller, Eustoquio Molina, José I. Canudo

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Planktic foraminifera across the Paleocene-Eocene transition at DSDP Site 401 indicate that the benthic foraminiferal mass extinction occurred within Subzone P 6a of Berggren and Miller (1988), or P5 of Berggren et al. (1995) and coincident with a sudden 2.0‰ excursion in δ13C values. The benthic foraminiferal extinction event (BFEE) and δ13C 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 δ18O in the 175 cm preceding the benthic foraminiferal extinction event followed by a sudden decrease of 1‰ (4°C) at the BFEE. The δ13C excursion occurred over 27 cm of sediment and, assuming constant sediment accumulation rates, represents a maximum of 23 ka. Recovery to pre- excursion δ13C values occurs within 172 cm, or about 144 ka. Climate cooling begins in Subzone P 6c as indicated by an increase in cooler water subbotinids and acarininids with rounded chambers and a decrease in warm water morozovellids.

Original languageEnglish (US)
Pages (from-to)129-158
Number of pages30
JournalMarine Micropaleontology
Issue number2
StatePublished - Jan 1997

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Palaeontology


  • Bay of Biscay
  • DSDP Site 401
  • Paleocene-Eocene
  • biostratigraphy
  • paleoecology
  • planktic foraminifera


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