Diversity of benthic foraminiferal faunas in Tertiary and Quaternary sediments of DSDP Hole 33-317_Site from the Manihiki Plateau, Pacific Ocean (Table 1)

A study is made of the benthic foraminifers (size fraction > 63 µm) recovered from 59 upper Eocene through Quaternary sediment samples at DSDP Site 317 (Leg 33), located at a depth of 2598 m in the central part of the Manihiki Plateau (South Pacific). The sediments cored are disturbed in only two samples. The stratigraphic assignements used are based on previous studies of planktic foraminifers and other microfossils. In total, 216 taxa are identified. A cluster analysis based on the 77 species which comprised 5% or more of the entire foraminiferal assemblage in at least one sample suggests the presence of 3 major biostratigraphic zones corresponding approximately to the following ages, zone A: middle Miocene-Quaternary; zones B-C: early Miocene-Oligocene; and zone D: Eocene. The most important faunal turnover occurred between the Eocene and the Oligocene; a less pronounced break took place between the early and the middle Miocene, and an additional minor turnover between the Oligocene and the early Miocene. Eighteen taxa are long-ranging, being recorded from the middle Eocene through the Pliocene-Quaternary. It is concluded that, in general, benthic foraminifers of the bathyal zone are poor worldwide stratigraphic guide fossils; the following taxa are conditionally considered as the most suitable in the Eocene-Quaternary sequence: Aragonia aragonensis, Quadrimorphina profunda, Nuttallides truempyi, Abyssamina poagi, Buliminella grata, Bulimina jarvisi, B. macilenta, Turrilina alsatica, Cibicides notocenicus, C. wuellerstorfi, Pyrgo murrhina. However, most of these species are relatively rare.