Sedimentation rate varies considerably based on biostratigraphy at Hole 1006A. It was calculated using 12 planktonic foraminiferal bioevents (Table 2) and the data are plotted on an age vs. depth curve as in Figure 3. We have used the planktonic foraminiferal events because some nannofossil events document reworking of very fine grained material in the section. The reworked specimens of some nannofossil species result in the presence of datum levels that are too highly positioned in the section shown in an age-depth plot in Figure 3, if sedimentation rates based on the planktonic foraminiferal biostratigraphy and cyclostratigraphy (see "Early Pliocene-middle Miocene cyclostratigraphy" section) are basically correct.
Calculated sedimentation rate varies from 1.32 to 19.25 cm/k.y. through the sequence. From the FO of G. crassaformis (4.5 Ma) to the FO of G. tumida (5.6 Ma), the sedimentation rate was ~4.9 cm/k.y. and from the FO of G. tumida to the LO of G. dehiscens (5.8 Ma) ~4.5 cm/k.y. However, because of the low recovery of Core 166-1006A-43X, the real LO of G. dehiscens may occur in the 9.5 missing meters. A significant shift in the sedimentation rate to 9.95 cm/k.y. occurs in the interval from the LO of G. dehiscens and the FO of G. conglobatus (6.2 Ma). Sedimentation rate increased to 11.8 cm/k.y. from the FO of G. conglobatus to the FO of G. margaritae (6.4 Ma). Between the FO of G. margaritae and the FO of C. nitida (8.1 Ma), the rate of sedimentation drastically decreased to 2.8 cm/k.y., whereas it increased again up to 6.85 cm/k.y. between the FO of C. nitida and the FO of G. plesiotumida (8.3 Ma). The next observed datum is the FO of N. humerosa (8.5 Ma), representing an interval of 200 k.y. with a sedimentation rate of ~19.25 cm/k.y. Sedimentation rate drastically decreased to 1.32 cm/k.y. between the FO of N. humerosa and the LO of the P. siakensis/P. mayeri group (11.4 Ma). An increase in the rate of sedimentation up to 8.9 cm/k.y. is observed between the LO of the P. siakensis/P. mayeri and the FO of Z. nepenthes (11.8 Ma). A further increase occurs in the interval between the FO of Z. nepenthes and the FO of F. fohsi robusta. This value, however, may not be real because of the very poor recovery of Core 166-1006A-71X. Finally, sedimentation rate decreased to 2.9 cm/k.y. between the FO of F. fohsi robusta (12.1 Ma) and the FO of F. fohsi lobata (12.5 Ma).