11. CALCAREOUS NANNOFOSSILS FROM THE SOUTHEAST GREENLAND MARGIN: BIOSTRATIGRAPHY AND PALEOCEANOGRAPHY¹

Wuchang Wei²

ABSTRACT

The distribution of calcareous nannofossils in Leg 152 sites on the southeast Greenland Margin is documented. The nannofossil biostratigraphy established here provides valuable age information for the recovered sediments and a number of important events, including the initiation of marine sedimentation in the Irminger Basin in the early Eocene (52–53 Ma), the onset of North Atlantic Deep Water around 11.5 Ma, and the earliest occurrence of dropstones in the Irminger Basin at about 7 Ma or older. Nannofossil assemblages indicate significant warmth in the high latitudes during the Eocene and progressive deterioration of the climate since the late Eocene. The last consistent occurrence of warm-water taxa at about 12 Ma in the Irminger Basin may suggest the onset of the cold East Greenland Current at this time. Reworked Cretaceous nannofossils in Pleistocene sediments may be the result of extensive discharge of icebergs from the North Sea-Denmark area beginning in the middle Pleistocene.

¹Saunders, A.D., Larsen, H.C., and Wise, S.W., Jr. (Eds.), 1998. Proc. ODP, Sci. Results,152: College Station, TX (Ocean Drilling Program).
²Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0215, U.S.A. wwei@ucsd.edu