EXTINCT FORAMINIFERA OF THE WESTERN ARCTIC OCEAN: CORRELATION TO THE GLOBAL DEEP-SEA EXTINCTION OF THE MID-PLEISTOCENE TRANSITION

A well-preserved Quaternary record of calcareous microfauna from the Northwind Ridge, western Arctic Ocean, demonstrates the last occurrences of several foraminiferal taxa (notably Cibicidoides spp., Ehrenbergina sp., and Stilostomella/Nodosaria spp.). Similar extinctions have been previously described in the Late Miocene to Pliocene strata in the Beaufort-Mackenzie Basin, but correlation between shelf areas and the deep ocean is suspect. Based on multi-proxy correlation with other Arctic Ocean cores and cyclostratigraphy, the Northwind Ridge extinctions are estimated to have taken place during the Mid-Pleistocene Transition (MPT, ca. 1.2 – 0.7 Ma). This time interval is known as a global extinction event of benthic foraminiferal fauna due to increasing impact of Pleistocene glaciations on oceanic circulation and biota. We infer that the MPT extinctions in the Arctic Ocean were caused by a transition from seasonal to perennial sea-ice conditions and expanding glaciations on adjacent land. Correlations between these last occurrences and extinctions in the world oceans will help understand the linkages between the Arctic Ocean and global climatic change.