Scientists of Ocean Drilling Program (ODP) Leg 162 recovered sedimentary sequences from the Norwegian-Greenland Sea and the North Atlantic (Sites 907 and 980-987). The main purpose was to study the climate evolution of the North Atlantic-Arctic region, including a detailed analysis of the Neogene history of planktonic and benthic micro-organisms.
The present study focuses on the analysis of silicoflagellate assemblages from the Miocene, a critical time during the Cenozoic, when the transition from Paleogene to late Neogene climates occurred. Biosilica-bearing sediments of this age were cored at two sites (907 and 982), and samples were obtained from Holes 907B and 982B.
Both sequences provide long, almost continuous records of the middle to late Miocene and have allowed a high-resolution analysis of silicoflagellates. Consequently, pre-existing zonal schemes for this realm (Locker and Martini, 1989; Ciesielski et al., 1989) have been refined and correlated with calcareous nannoplankton zones in Hole 982B. The recovery of an excellent paleomagnetic record in Hole 907B allows a tentative correlation (Channell et al., Chap. 9, this volume) with the silicoflagellate stratigraphy presented herein. Because of the existence of other interpretations of the paleomagnetic record for the Miocene at Site 907 (Shipboard Scientific Party, 1996), no attempt is made toward such a correlation.