Eocene to Early Miocene Benthic Foraminifera DSDP Leg 39, South Atlantic

Few reports of benthic foraminiferal faunas from deep-sea cores of the Tertiary have been published. Notable exceptions are the works of Berggren (1972, 1975), Douglas (1973), and Vincent et al. (1974) on samples taken by the Deep Sea Drilling Project. Older works, providing the reference faunas for these deeper, open marine sections include Beckmann (1953), Bandy (1970), Cushman and Renz (1948), Cushman and Stainforth (1945), Palmer (1940), AGIP (1959), and Bermudez (1949): see Berggren and Phillips (1971) for a more extensive bibliography. Because of the time between publication of these two groups of works, and although some taxonomic revisions are presently in progress (for example, Tjalsma, personal communication), there is currently a lack of standardized and updated taxonomy. Consequently, the faunas reported here are given names directly from the older literature and the source of each name is listed in the Appendix. When the taxonomy is revised it will then be reasonably simple to incorporate the taxa listed in this report. Benthic foraminifera were studied from the Tertiary of Sites 356, 357, 358, and 359 (Table 1), and those—both the smaller and larger forms—from Site 357 are treated in greater detail. Coring gaps, hiatuses, and preservational effects resulted in less complete sections at the other sites. Presently, one of the crucial problems in the study of benthic foraminifera, particularly those of the geologic past, is to reinterpret their distribution patterns in terms of chemical, physical, and/or biological parameters. The seemingly straightforward explanation of water depth as a controlling factor has been questioned in recent years (Streeter, 1973; Douglas, 1973). Thus, one of the purposes of this study is to document faunal changes at this site with accompanying temperature fluctuations determined from oxygen isotope ratios. Stratigraphic and evolutionary conclusions from this sort of study are few, as appearances and disappearances at the site may be ecological rather than evolutionary events.