Late Cenozoic Paleo-oceanography of Norwegian Greenland Sea and Northeast Atlantic: Benthic Foraminiferal Evidence: ABSTRACT

Abstract

Analysis of late Cenozoic deep-sea benthic foraminifera from DSDP Legs 12 and 38 was conducted to determine faunal patterns and relate them to the evolution of bottom-water circulation. In the Norwegian Greenland Sea, middle to late Miocene sites from 1,200 to 1,800 m present water depth have an agglutinated benthic foraminiferal assemblage dominated by Martinottiella communis and Spirosigmoilinella sp.; shallower and deeper sites are barren. A regional unconformity appears to span an interval from within the late Miocene to the early Pliocene. A sparse early Pliocene calcareous assemblage is dominated by Cassidulina teretis. Intervals interpreted to represent colder episodes within the late Pliocene-Pleistocene are either barren or contain an assemblage dominated by Orid rsalis tener. These alternate with a more diverse assemblage dominated by Cibicides wuellerstorfi (> 1,500 m) or C. teretis, Islandiella norcrossi, and Melonis barleeanum (< 1,500 m) that represent interstadial or interglacial intervals. North Atlantic sites show higher benthic foraminiferal diversity and better preservation throughout most of the late Cenozoic than the Norwegian Greenland Sea sites. The Norwegian Greenland Sea does not appear to have been a source of North Atlantic deep water during the Miocene to early Pliocene interval because conditions were not conducive to the preservation of calcareous foraminifera. late Pliocene-Pleistocene assemblage changes in the Norwegian Greenland Sea are interpreted to represent changes in bottom- and surface-water circulation. Episodes of ice cover inhibited bottom-water formation and affected the food supply to the benthos. These intervals alternated with times of more productive ice-free conditions, some of which may have been conducive to bottom-water formation. End_of_Article - Last_Page 898------------