Five factors explain 84% of the faunal variation at Site 1006 (37 samples and 134 taxa) (Table 1; Fig. 1). Benthic foraminifers indicate that sedimentation was primarily in situ at Site 1006, with periods of increased downslope transport of shallow-water material. Factor 3 is characterized by high abundances of transported, shallow-water taxa (dominated by Reusella spinulosa, Elphidium spp., and Amphistegina/Asterigerina spp.) (Fig. 3). The faunal distributions that characterize Factor 3 show that low numbers of shallow-water specimens were transported downslope and deposited at Site 1006 throughout the middle to late Miocene, punctuated by periods of increased downslope transport of shallow-water taxa (Fig. 1, Fig. 3). Comparison of the Factor 3 assemblage with the isotope and sequence stratigraphic records shows a probable correlation between downslope transport of shallow-water material and sea-level changes (M.E. Katz, J.D. Wright, and K.G. Miller, unpubl. data).
To evaluate circulation changes that may be reflected in the benthic foraminiferal biofacies changes, we deleted transported, shallow-water taxa (Amphistegina/Asterigerina spp., Baculogypsinoides sp., Elphidium spp., Planorbulina spp., Reusella spinulosa, and Tretomphalus spp.) from the dataset to identify patterns in the in situ benthic foraminiferal faunas. Changes in these in situ faunas do not appear to be closely related to sequence stratigraphy (Fig. 2). Rather, biofacies fluctuations may have resulted from circulation changes that are only indirectly related to sea-level variations on the m.y. scale (e.g., Wright et al., 1992; M.E. Katz, J.D. Wright, and K.G. Miller, unpubl. data).
Dissolution indices (percentages of planktonic foraminifer fragments and percentages of planktonic foraminifers) (Table 1) indicate the presence of an interval of increased dissolution in the middle Miocene section at Site 1006 (Fig. 4), possibly corresponding to isotope event Mi5 (M.E. Katz, J.D. Wright, and K.G. Miller, unpubl. data).