The paleomagnetic signal derived from sediments at Site 1007 was not strong enough to provide stratigraphic control except above 2 mbsf. Well-preserved calcareous nannofossils were recovered throughout the section. We found nine calcareous nannofossil events defined by Takayama and Sato (1987). The bottom acme zone of Emiliania huxleyi (0.08 Ma) and the top of Pseudoemiliania lacunosa (0.41 Ma) are located between Samples 166-1007B-1H-2, 39 cm, and 1H-2, 59 cm. The sharp basal contact of turbidite is situated in this interval. A hiatus between 0.08 and 0.41 Ma (at least) is assumed at this sharp erosional contact. The top of Reticulofenestra asanoi (0.85 Ma) is located between Samples 166-1007B-1H-3, 24 cm, and 1H-3, 59 cm. The bottom of Gephyrocapsa parallela (0.95 Ma) is observed between Samples 166-1007B-1H-4, 24 cm, and 1H-4, 39 cm. The bottom of R. asanoi (1.16 Ma) occurs between Samples 166-1007B-1H-CC, and 2H-1, 19 cm. The top of large Gephyrocapsa (1.20 Ma) is found between Samples 166-1007B-2H-3, 39 cm, and 2H-3, 59 cm. The bottom of large Gephyrocapsa (1.44 Ma) is observed between Samples 166-1007B-5H-3, 13 cm, and 5H-3, 23 cm. The bottom of Gephyrocapsa oceanica (1.65 Ma) occurs between Samples 166-1007B-4H-1, 59 cm, and 4H-1, 99 cm. The bottom of Gephyrocapsa caribbeanica (1.72 Ma) is observed between Samples 166-1007B-5H-5, 133 cm, and 5H-6, 13 cm.
Figure 2 depicts the relationship between sampling depth and the datum of the calcareous nannofossil biostratigraphy. It indicates a change in sedimentation rate at least during the last 1.72 m.y. The sedimentation rate dramatically drops at depths above 12 mbsf, and there is a hiatus characterized by sharp erosional contact at 2 mbsf.