Ocean Drilling Program, United States

Quaternary and Neogene benthic foraminifer faunas from Ocean Drilling Program Leg 149, Holes 898A, 898B, and 900A are documented. The Quaternary sections show a mixed signal of turbidite and hemipelagic levels, especially in sediments from Site 898. No benthic foraminifer assemblages associated with turbidite deposits were identified in Hole 900A sediments, but this may have been a result of sample spacing in the core. Hemipelagic sediments from Hole 900A have a less diverse benthic foraminifer assemblage than those from Holes 898A and 898B. Site 898 has abundant turbidite deposits and a record of dynamic bottom-water changes between North Atlantic Deep Water and Arctic Bottom Water. At the Pliocene/Pleistocene boundary, Nuttallides umbonifera, characteristic of Antarctic Bottom Water, becomes more significant. The abundance of this species also fluctuates throughout the Miocene, especially the upper Miocene, perhaps reflecting deep-water salt-balance changes caused by the Messinian salinity crisis.