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Paleocene and Eocene nannofossil flora from Deep Sea Drilling Project Legs 25 and 40 were analyzed in order to provide a basis of comparison with DSDP Legs 36 and 71 and with other South Atlantic assemblages. A mid-latitude biostratigraphic zonation, using previously described zonal markers, was adopted for the southwest Indian Ocean. Various diagenetic effects were noted in the sedimentary sequences. Some of these mask to some extent paleoecologic signals, particularly those generated by the Discoaster/Chiasmolithus ratio. INTRODUCTION A significant result of deep sea drilling in the vicinity of the Falkland Plateau during DSDP Legs 36 (Barker, Dalziel, et al., 1977) and 71 (this volume) was the recovery of extensive high-latitude Paleogene carbonate sediments. However, there exist below 30° South in the South Atlantic few other drill sections to which the Leg 36 and 71 sequences can be compared. One may be obliged, therefore, to turn to drill sequences in the southwestern Indian Ocean to fill in gaps for regional Paleogene biogeographic, biostratigraphic, and paleoceanographic studies in this part of the Southern Hemisphere. Unfortunately, stringent deadlines precluded the publication of detailed biostratigraphic data in the DSDP Initial Reports for the several southeastern Indian Ocean sites drilled during DSDP Leg 25 (Simpson, Schlich, et al., 1974; see Fig. 1), and species distributions and abundances of calcareous microfossils were largely unreported. The present study, therefore, was undertaken to examine in more detail than originally published the calcareous nannofossil content of Paleocene to Eocene cores recovered during DSDP Leg 25. In addition to the Leg 25 material, Paleocene and Eocene samples from DSDP Leg 40, Holes 360 and 361, were examined (Bolli, Ryan, et al., 1978). The samples provide good control because their latitude is similar and they are relatively close to Leg 25 sites (Leg 40 was off the Cape of Good Hope, South Africa); they therefore provide a check on the accuracy of the zonation adopted for the Leg 25 material. The Leg 40 samples cover the upper Paleocene through Eocene, whereas the Leg 25 samples also include the lower Paleocene. The fourth of six cruises designed to investigate the marine geology of the Indian Ocean, Leg 25 began in June, 1972, the 100th anniversary of the voyage of H.M.S. Challenger. Among the objectives for this leg 1 Ludwig, W. J., and Krasheninnikov, V. A., Init. Repts. DSDP, 71: Washington (U.S. Govt. Printing Office). 2 Present address: DeGolyer and MacNaughton, One Energy Square, Dallas, Texas 75206. Figure 1. Location map for Leg 25 and Leg 40 sites. was the establishment of a mid-latitude biostratigraphic zonation above the carbonate compensation depth (CCD). As the shipboard Coccolith stratigrapher for Leg 25, Müller (1974) offered age dates for cores and some discussion of dissolution and/or paleoecology of the nannofloras, but her report did not contain range charts for occurrences of individual taxa. Instead, Martini's (1970, 1971) zonation was used to assign zones to each 150 cm core section. Muller's brief discussion of dissolution sequences reflected observations published prior to the Leg 25 Initial Reports (e.g., Bukry, 1971b, 1973b; Roth, 1973; Wise, 1973.). Müller noted that overgrowths are due mainly to the sediment type. Nannofossil ooze was described as having poorly preserved coccoliths whereas the preservation in marl ooze was good to excellent. Bukry (1974) age dated the Leg 25 core sections using his low-latitude zonation (Bukry, 1973a). He presented a range chart for 11 lower Eocene samples from Site 245 but did not indicate species abundances. He also calcu-

Paleocene and Eocene Calcareous Nannofossils from Deep Sea Drilling Project Legs 25 and 40, South and East of Africa