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doi:10.2204/iodp.proc.303306.211.2010

Results

The age model in this study is established primarily on the oxygen isotope stratigraphy and some well-known calcareous nannofossil biostratigraphic events for Site U1308 based on Sato et al.

Fourteen genera and 15 species were recognized at Site U1308. Almost all samples contain well-preserved nannofossils throughout the sequence except in the ice-rafted detritus (IRD) intervals where some samples contain poorly preserved nannofossils or are barren (Fig. F2). Badly dissolved specimens characterize these intervals.

Genus Gephyrocapsa, which includes Gephyrocapsa aperta, Gephyrocapsa sinousa, G. caribbeanica, G. muellerae, and G. oceanica, is dominant throughout the sequence (Fig. F3). The upper part of the sequence is characterized by abundant occurrences of Calcidiscus leptoporus, Coccolithus pelagicus, and Emiliania huxleyi. Gephyrocapsa parallela, Helicosphaera carteri, small specimens (<4 µm) of Reticulofenestra, and Umbilicosphaera sibogae are present throughout the sequence; however, these taxa are low in abundance (a few percent) in the examined interval. Phontosphaera spp., Syracosphaera pulchra, and Umbellosphaera spp. exhibit sporadic occurrences throughout the sequence (Fig. F3). F. profunda is nearly absent throughout the sequence at Site U1308.