Diatom biostratigraphy of ODP Hole 172-1063D sediments

During Leg 172, Site 1063 was unexpectedly found to contain intervals with rich assemblages of diatoms, both in species diversity and absolute abundance. These intervals correlated with well-defined gamma-ray attenuation bulk density lows. Sampling of the upper four cores at 10-cm spacing provided an in-depth examination of subtle changes in the diatom assemblages associated with these lows. The biostratigraphic data gathered in this study are presented here along with numerous illustrations of the common taxa observed. The modern ecological affinities, as reported in numerous literature sources, of many of these taxa are collated by species. The diatom species observed in this material presently occur in many different parts of the Atlantic as well as other areas of the globe. Some species are restricted to warm waters, and others are absent from warm waters. So, a brief discussion of specific environmental restrictions, and their bearing on indication of sediment transport, is included in this report.