Samples were processed to separate the clay-sized nannofossil fraction from the rest of the sediments by suspending the raw sediment in water then transferring the clay-sized portion to a coverslip using a pipette. The material on the coverslip was dried, then the coverslip was cemented to a glass microscope slide using Norland optical adhesive. Although this sample preparation technique is more time consuming than the standard smear-slide analyses done aboard ship for all of the core-catcher samples, it allows for better distribution of nannofossils on a microscope slide and a much higher confidence level of reproducibility in quantitative or semiquantitative analyses. All samples were processed this way except for the core-catcher samples and the relatively small numbers of smear-slide samples routinely prepared from split core surfaces during the Leg 170 cruise. In the latter case, raw sediment samples were mixed with enough water to form a thin, viscous slurry on a coverslip, then the slurry was allowed to dry before it was cemented to a glass slide with Norland optical adhesive. All samples were observed and analyzed using phase contrast and cross-polarized light under magnifications of 500× and 1250×. The diameter of the field of view at 1250× is ~0.16 mm.
Calcareous nannofossil range-distribution charts were constructed for all nannofossil species observed in each hole cored at Sites 1039, 1040, 1041, 1042, and 1043. The distribution, relative abundance, and relative preservation of nannofossil species observed in the cores at these sites are plotted on Tables T1, in PDF format; T2, in PDF format; T3, in PDF format; T4, in PDF format; T5, and T6, in PDF format; along with the nannofossil zonation. Letters used to express species abundance are keyed to the log10 of the number of specimens of a particular species or genus likely to be observed in any one field of view at a magnification of 1250×. The letters are denoted as follows:
Through visual inspection at 1250×, a qualitative determination was made of the state of preservation of the nannofossils in each sample. In any given sample, the state of preservation may differ between each individual species, genus, or morphologic group. Thus, any qualitative measurement of a given sample must be based on the overall preservation qualities of the nannofossil assemblage. The following basic criteria were used to qualitatively describe the degree of preservation, dissolution, or overgrowth of a nannofossil assemblage:
Descriptions of species noted in this study and their references can be found in Perch-Nielsen (1985). A list of species noted in this study can be found in the "Taxonomic Appendix".