CONCLUSIONS

The primary objective of this paper has been to summarize Paleocene to Eocene nannofossil biostratigraphy of Sites 1135, 1136, and 1138 on the KP and to compare the data with those from other sites on the KP.

1. The K/T boundary at Site 1138 appears to be complete in terms of assemblage succession, isotopic signature, and reworking of older (Cretaceous) nannofossil taxa. There is a significant color change, a negative carbon isotope shift, and nannofossil turnover. These three lines of evidence indicate that the boundary should be placed at Sample 183-1138A-52R-3, 127-128 cm (490.95 mbsf). These data compare favorably with other high-latitude sites, but this placement of the boundary is not in agreement with the current paleomagnetostratigraphy, which shows a paleomagnetic normal rather than reversed signature for this interval.
2. The biogeography of the genus Hornibrookina in the Southern Ocean indicates the presence of some type of water mass boundary over the KP during the very early Paleocene.
3. The application of an upper Paleocene-Eocene nannofossil biostratigraphy based on the Martini (1971) and Okada and Bukry (1980) zonal schemes is possible in the high latitudes, but significant problems arise in determining the absolute age of the FO and LO of some index taxa when comparing low-latitude to high-latitude sites. The Wei and Pospichal (1991) high-latitude scheme is more applicable for the lower Paleocene.
4. Discoasters and sphenoliths declined in abundance and diversity from the late Paleocene-early Eocene to the middle Eocene. This reflects the global cooling of the oceans during the middle Eocene.