Neogene planktonic foraminifera of the western tropical Indian Ocean

Neogene calcareous sediments were recovered at 12 sites in the western Indian Ocean (Table 1). Approximately 1000 10-cm**3 samples, at a sampling interval of about 1.5 m, were collected from one hole at each site for planktonic foraminifer analysis. Samples were washed through a 63-?m mesh sieve. Dried samples were weighted before and after washing to obtain the percentage of sand-size components, which are given in Table 2. The distribution of selected planktonic key species in each hole is reported in Tables 3-14, where the occurrence of a species in a sample is indicated with a cross (x) and a slash sign (/) indicates that this species is extremely rare or presents some taxonomic ambiguity.
A visual estimate of the abundance of various components other than planktonic foraminifers is also given in Tables 3-14, with the abbreviations R (rare), F (few), C (common), and A (abundant). An estimate of the foraminiferal fauna preservation state is reported at the right of each table using a qualitative preservation scale as follows: G (good), M (moderately good), P (poor), and VP (very poor). Also reported are the abundances of planktonic foraminifer fragments and foraminifers embedded in a calcareous matrix, both of which are a function of the preservation state (the first reflecting the intensity of carbonate dissolution and the second, the occurrence of recrystallization). Table 15 summarizes the biostratigraphic zonal assignments. An overview of planktonic foraminifer distribution in Neogene sediments from Ocean Drilling Program (ODP) Leg 115 has been presented in Backman, Duncan, et al. (1988) based on a preliminary examination of core-catcher samples. From the more detailed investigations conducted in this study, only tables and species illustrations are presented in this report because of publication deadlines. Taxonomic and biostratigraphic discussions will be presented elsewhere.