High accumulation rates and the presence of well-preserved, abundant diatoms in Site 983 sediments from the Gardar Drift gave us the opportunity to refine the Pleistocene diatom biostratigraphic resolution of the high-latitude North Atlantic. Eight Pleistocene diatom datum events are identified and, for the first time, tied directly to the oxygen isotope record and paleomagnetic stratigraphy of Site 983. These datum events are (1) the last occurrence (LO) of Proboscia curvirostris at 0.3 Ma, (2) the LO of Thalassiosira jouseae at 0.3 Ma, (3) the LO of Nitzschia reinholdii at 0.6 Ma, (4) the LO of Nitzschia fossilis at 0.68 Ma, (5) the LO of Nitzschia seminae at 0.84 Ma, (6) the first occurrence (FO) of N. seminae at 1.25 Ma, (7) the FO of Proboscia curvirostris at 1.53 Ma, and (8) the FO of Pseudoeunotia doliolus at 1.89 Ma. Most of these datums are found to be synchronous between the middle and high latitudes of the North Atlantic and the North Pacific. On the basis of these datums, four high-latitude North Atlantic diatom zones are proposed for the Pleistocene. The record of diatom abundance and preservation at Site 983 gives evidence for the influence of fluctuating Pleistocene climatic conditions on diatom productivity in the high-latitude North Atlantic.

Supplement to: Koç, Nalân; Hodell, David A; Kleiven, Helga F; Labeyrie, Laurent D (1999): High-resolution Pleistocene diatom biostratigraphy of Site 983 and correlations with isotope stratigraphy. In: Raymo, ME; Jansen, E; Blum, P; Herbert, TD (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 162, 1-12