The occurrence of calcareous nannofossils are shown in Tables T2 and T3, and pollen and spores are shown in Table T4. Stratigraphic distribution of pollen and spores is shown in Figure F2.
Hole 1095A contains some stratigraphically important species of calcareous nannofossils in the upper part of the core. Emiliania huxleyi, whose appearance defines the base of the calcareous nannofossil Zone CN15 (Okada and Bukry, 1980), is found only in Sample 178-1095A-1H-2, 70 cm (2.16 mbsf). Samples 178-1095A-3H-5, 18.5 cm, through 5H-1, 90 cm (16.64-31.25 mbsf) contain Pseudoemiliania lacunosa without E. huxleyi, which suggests that this interval belongs to Zone CN13. The presence of larger specimens of Gephyrocapsa (~5 µm) in Sample 178-1095A-5H-1, 90 cm (31.25 mbsf), indicates a possible correlation with Subzone CN13b. The disappearance of this species occurs in this subzone at 1.24 Ma (e.g., Takayama and Sato, 1987; Raffi and Flores, 1995).
Although samples from Hole 1095A contain a few diagnostic species, they are rare in Hole 1095B. In this hole, the presence of only Reticulofenestra pseudoumbilica indicates that the samples from Hole 1095B should be correlated with Zone CN11 and older.
Onset termination of Chron C1r.1n (1.07 Ma) (Cande and Kent, 1995) occurred at 29.75 mbsf in Hole 1095A (Barker, Camerlenghi, Acton, et al., 1999). The last occurrence of large Gephyrocapsa spp. (1.22-1.24 Ma) occurred between Samples 178-1095A-4H-6, 14 cm, and 5H-1, 90 cm (27.94-31.25 mbsf). Age assignment of calcareous nannofossils is consistent with those suggested by magnetostratigraphy. Unfortunately, however, there are no age constraints near the possible hiatus, which was suggested to occur at ~60 mbsf (see "Magnetostratigraphy" in Shipboard Scientific Party, 1999).
Decreasing biosiliceous sediments and increasing biocalcareous sediments in the uppermost Pliocene to the mid-Pleistocene have been observed at Sites 1096 and 1101 on the continental rise (Barker, Camerlenghi, Acton, et al., 1999). The lower number of calcareous microfossils at Site 1095 may be affected by its deeper (3842 m) water depth relative to Sites 1096 (3152 m) and 1101 (3280 m), or may be due to a missing section in Hole 1095A. The occurrence of calcareous nannofossils between Samples 178-1095A-4H-4, 114 cm, and 5H-1, 90 cm (26.44-31.25 mbsf) (1.03-1.10 Ma, based on the magnetostratigraphic control points in Barker, Camerlenghi, Acton, et al., 1999), show the same pattern as those of diatoms at Site 1095 (Iwai, 2000b). Cowan (2000) found 19 foraminifer-bearing units separated by thicker barren laminated clayey silts at Site 1101 in the interval correlating to between 2.2 and 0.76 Ma. Biogenic-rich massive intervals were deposited during interglacial periods (Cowan, 2000). The occurrence of calcareous nannoplankton in the Southern Ocean is used as a proxy for the southward oscillation of the Polar Front (e.g., Burckle et al., 1996; Bohaty and Harwood, 1998). However, the lack of subantarctic-subtropical warmer diatom species in those sample intervals in Hole 1095A (Iwai, 2000b) suggests that the increase in biocalcareous sedimentation was not the result of the southward migration of the Polar Front (warming) during the interglacial period. It may have resulted from the fluctuation of the carbonate compensation depth (CCD), which was affected by the deep-water circulation changes.
Table T3 shows stratigraphic occurrences of calcareous nannofossils in Holes 1097A and 1103A. Samples from these two holes contain rare and/or barren nannofossils and reworked Cretaceous specimens. Sample 178-1097A-8R-CC contains only a poorly preserved Gephyrocapsa specimen, and it is likely to be correlated with the Pleistocene. Moreover, Dictyococcites specimens in Samples 178-1097A-28R-CC, 178-1103A-33R-CC, and 178-1103A-34R-CC are present in Unit S3. Specimens observed here are small (~3 µm in diameter) and are not the large Dictyococcites species usually found in the Paleogene. The presence of small Dictyococcites species also suggests that these horizons were deposited under comparatively open marine conditions.
Reworked Cretaceous foraminifers and radiolarians have also been observed in sediments from Units S1 and S2 at Site 1097 and Units S1 and S3 at Site 1103 (Barker, Camerlenghi, Acton, et al., 1999). The most abundant benthic foraminiferal assemblages and well-preserved specimens of Cassidulinoides parkerianus in Samples 178-1103A-31R-CC and 33R-CC suggest that those samples were deposited under the glaciomarine environment (Barker, Camerlenghi, Acton, et al., 1999). The results of calcareous nannofossil analysis are consistent with those of foraminifers and radiolarians (Barker, Camerlenghi, Acton, et al., 1999).
A total of 31 pollen taxa and 17 spore taxa have been observed in the samples (Table T4). Pollen and spore assemblages are characterized by species of genus Phyllocladidites, Podocarpidites, Nothofagidites, Proteacidites, Tricolpites (pollens), Psitriletes, and Foveotriletes (spores). Total grains are, in general, <100 grains per 10 g of dry sediment (Fig. F2). The pollen and spore concentration maximum of 210 grains per 10 g of dry sediment occurs in Sample 178-1103A-13R-CC (113.2 mbsf) within the lower portion of Unit S1. Most of these grains, however, were decayed and considered to be recycled from older sediments. Nothofagidites, the genus for fossil pollen referred to as Nothofagus, occurred through seismic Units S1-S3. The occurrences of Nothofagidites spp. were generally rare and statistically meaningless in those samples. One exception occurred in Sample 178-1103A-34R-CC (319.60 mbsf), where four specimens of Nothofagidites lachinae were observed. This species was used to indicate the presence of a Nothofagus forest on the Antarctic continent (Fleming and Barron, 1996). Overall, at these sites the sparse occurrence of pollen and spores makes it difficult to assess the nature of the Antarctic terrestrial vegetation.