13. LATE PALEOGENE (EOCENE TO OLIGOCENE) BENTHIC FORAMINIFERAL OCEANOGRAPHY OF THE GOBAN SPUR REGION, DEEP SEA DRILLING PROJECT LEG 801

Major benthic foraminiferal changes occurred in the late Eocene at Site 549. A Nuttallides truempyi-dominated as-semblage was replaced by a buliminid assemblage (-40-38.5 m.y. ago); this change in faunal abundance was appar-ently a circum-Atlantic event. The buliminid assemblage was replaced, in turn, by an assemblage dominated by strati-graphically long-ranging and bathymetrically wide-ranging taxa just below the Eocene/Oligocene boundary (~37.5 m.y. ago). A series of late Eocene to earliest Oligocene first and last appearances of taxa accompanied these abundance changes. Similar changes in faunal abundance occurred at Site 548, but the incomplete record recovered at Site 548 pre-vents a firm dating of the changes. No major benthic foraminiferal changes (denoted by the extinction of Hαntkeninα, Cribrohαntkeninα, and Globorotαliα cerroαzulensis) were associated with the Eocene/Oligocene boundary at these sites; instead, benthic foraminiferal abundance changes, last appearances (both extinctions and local disappearances), and first appearances occurred throughout the late Eocene to earliest Oligocene interval (-40-36 m.y. ago). Benthic foraminiferal δ 1 8θ increased ~ l.O ‰ in the late Eocene to earliest Oligocene ( ~ 38-36.5 m.y. ago) at Site 549. Most ( ~ 0.7‰) of this increase occurred simultaneously with a 0.6 ‰ increase in benthic foraminiferal δ13C as a ge-ologically rapid event in the earliest Oligocene (-36.5 m.y. ago). The major benthic foraminiferal abundance change (-40-38 m.y. ago) predates the major isotopic enrichments. A prominent seismic horizon, Reflector R4, has bee