Late Paleogene (Eocene to Oligocene) Paleoceanography of the Northern North Atlantic.

• Main Author: Miller,Kenneth George
• Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
• Format: Text
• Language: English
• Published: 1982
• Subjects: Biological Oceanography; Physical and Dynamic Oceanography; *CIRCULATION; *PALEONTOLOGY; THESES; REFLECTION; STRATIGRAPHY; HISTORY; SEISMIC WAVES; NORTH ATLANTIC OCEAN; ABYSSAL ZONES; OCEAN BOTTOM; RADIOACTIVE ISOTOPES; OCEANIC CRUST; FOSSILS; FORAMINIFERA; *Ocean circulation; *Paleoceanograph; Arctic; Greenland; Foraminifera*; Greenland Sea; Labrador Sea; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA121674; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA121674

Seismic stratigraphic evidence indicates that a major change in abyssal circulation occurred in the latest Eocene-earliest Oligocene of the North Atlantic. Reflector R4 reflects a change from weakly (Eocene) to vigorously circulating bottom water (early Oligocene). Sediment distribution studies indicate a northern source for this bottom water, probably from the Arctic via the Norwegian-Greenland Sea/Faeroe-Shetland Channel. Current-controlled sedimentation and erosion continued through the Oligocene; however, above reflector R3 (upper Oligocene), the general intensity of abyssal currents decreased. Above reflector R2 (lower Miocene) a further reduction in abyssal currents resulted in more coherent current-controlled sedimentation and a major phase of sediment drift development. Major deep-sea benthic foraminiferal changes occurred between the middle Eocene and earliest Oligocene: an agglutinated assemblage was replaced by a calcareous assemblage (abyssal Labrador Sea), and an indigenous Eocene calcareious fauna became extinct (abyssal Bay of Biscay). In shallower Atlantic sites ( 3km paleodepth), a Nuttallides truempyi assemblage was replaced by an assemblage of long- and wide-ranging taxa in the early late Eocene.