Preliminary biostratigraphies using calcareous nannofossils and planktonic foraminifers, in addition to paleobathymetry using benthic foraminifers, were determined from core-catcher samples and augmented by samples within cores to refine placement of datum levels and assemblage boundaries. Group abundance, group preservation, and species frequencies were recorded for each sample in the JANUS database.
Correlation of the nannofossil and foraminiferal zonal schemes to magnetostratigraphy are shown in Figure F5. Datum levels are listed in Tables T3 and T4. We used the time scale of Berggren et al. (1995b). Subdivision of the Quaternary into Holocene and Pleistocene was not performed with the shipboard samples. Thus, the Pleistocene as used in this volume may include the Holocene.
The zonal scheme of Martini (1971; modified by Perch-Neilsen, 1985) was used for Cenozoic calcareous nannofossils, although reference to the zonation of Bukry (1973, 1975; zonal code numbers added and modified by Okada and Bukry, 1980) was also made, particularly where better biostratigraphic resolution was possible with the latter. The zonation of Martini (1971) represents a good framework for biostratigraphic discrimination of midlatitude floral assemblages. The Cenozoic zonal schemes of Martini (1971) and Okada and Bukry (1980), together with the geomagnetic polarity time scale, are presented in Figure F5. Proxies to some of the defining events of the (sub)zones of Martini (1971) and Okada and Bukry (1980) are used, following Shafik et al. (1998), and are included in Figure F6. Cenozoic biostratigraphic events, including but not limited to the zonal/subzonal indicators of Martini (1971) and their proxies, are listed in Table T3.
Standard smear slides were made of all soft lithologies. Smear slides of indurated lithologies were prepared using the technique of Monechi and Thierstein (1985). Calcareous nannofossils were examined by means of standard light microscope techniques under cross-polarized and transmitted light at 1000× . We have adopted a simple system to characterize preservational states:
Relative abundance estimates for individual species were categorized as below:
We applied the zonal schemes of Berggren et al. (1995a, 1995b) and Jenkins (1985, 1993) for the Cenozoic. Ages of species datum levels (Table T4) are largely from Berggren et al. (1995a, 1995b, and references therein) and augmented by ages from Chaproniere et al. (1995) in reference to the zonal marker species of Jenkins (1985, 1993) (Fig. F7). In some cases datum level ages were amended on the basis of shipboard magnetostratigraphy. Taxonomic concepts for Neogene and Paleogene taxa are illustrated in Kennett and Srinivasan (1983), Bolli and Saunders (1985), Toumarkine and Luterbacher (1985), Jenkins (1971), and Hornibrook et al. (1989).
Unlithified to semilithified core sediment samples were wet-sieved over a 63-µm mesh screen and dried. Lithified material was crushed to pea size, boiled in a solution of Calgon diluted to 1% by weight, and then sieved and dried as before. Planktonic species relative abundances were estimated qualitatively and reported using the following categories:
Preservational characteristics were determined as follows:
Benthic foraminifers were examined from the >63-µm size fraction. However, in samples in which tests are strongly recrystallized only the >150-µm size fraction was studied. Initial processing of the core-catcher samples used for benthic and planktonic foraminiferal studies was similar. The generic classification of Loeblich and Tappan (1988) was used with some exceptions, which mainly reflect subsequent taxonomic revisions. Taxonomic assignments followed those of van Morkhoven et al. (1986), Miller and Katz (1987), Thomas (1990), Katz and Miller (1991), Mackensen and Berggren (1992), and Mackensen (1992).
Benthic foraminifers provide limited biostratigraphic age control for Leg 182 samples and all zones recognized are local assemblage zones. Benthic foraminifers are used to estimate paleobathymetry, to identify periods of downslope transport of platform-derived material, and to identify major changes in paleocirculation regimes. Paleobathymetric estimates are primarily based on van Morkhoven et al. (1986). Bathymetric zones are defined as follows:
The relative abundances of benthic foraminifers were estimated as follows: