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Rigil Guyot: Hole U1374A

Hole U1374A was the second site to be drilled on Rigil Guyot. The first core contained 6.64 m of unconsolidated pelagic sediment, with an additional 0.62 m of volcanic sandstone at the bottom. Eleven samples were examined through the interval of pelagic sediment (Table T1). The first sample (330-U1374A-1R-1, 99–100 cm) contains Ceratolithus cristatus and G. caribbeanica, with an assemblage of long-ranging background flora, suggesting an age no older than Pleistocene. Sample 1R-2, 130–131 cm, contains the LAD of Helicosphaera sellii, and Sample 1R-3, 99–100 cm, contains the LAD of Calcidiscus macintyrei, which both occur within Subzone CN13b. These taxa persist to the base of the pelagic sediment, and no discoasters were observed in any of the samples, indicating that the base of the pelagic cap recovered in Hole U1374A contains calcareous nannofossil assemblages of early Pleistocene age (Zone CN13).

Indurated sandstone from Samples 330-U1374A-3R-1, 30 cm, and 3R-1, 70 cm, contain nannofossils in rare abundances from the Upper Cretaceous. The sample at 30 cm has a lower species richness than the sample at 70 cm (11 species versus 17 species, respectively), both contain Upper Cretaceous species including Prediscosphaera cretacea, Prediscosphaera spinosa, Arkhangelskiella specillata, Eiffellithus turriseiffelii, Micula decussata, Microrhabdulus belgicus, and Nephrolithus frequens, indicative of Zone CC26 (late Maastrichtian).