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doi:10.2204/iodp.proc.320321.212.2013

Methods

Four samples from CaCO₃-rich sediments from Sections 320-U1331C-17H-3 and 17H-4, 31 samples from Sections 320-U1333A-16X-1 to 20X-2, and 9 samples from Sections 320-U1333B-19X-1 to 20X-3 were analyzed. All samples extended over 2 cm of core and were from the few levels in the lower Eocene and lower middle Eocene where carbonate-rich sediments were present (Pälike et al., 2009).

Samples were dried at 70°–80°C overnight and then weighed. Dried sediment samples were treated with 3% hydrogen peroxide solution overnight and washed through a 63 µm nylon mesh sieve. The residue was then dry-sieved over a 149 µm sieve, and foraminifers were picked from aliquots of the >149 µm size fraction. Because of low abundances of foraminifers in some sections, the numbers of foraminifers counted was less than 200 individuals in some samples. All picked foraminifers were arranged on an assemblage slide for identification of species. The diversity and equitability of the assemblages were estimated using the Shannon-Wiener index. The main source of foraminiferal systematics is Loeblich and Tappan (1988), which compiled well-known works of Plummer (1926), Cushman and Jarvis (1932), Cushman (1946, 1951), and Brotzen (1948). We examined the systematic works of Tjalsma and Lohmann (1983), van Morkhoven et al. (1986), and Jones (1994) for the cosmopolitan deep-sea foraminifers and Kaminski and Gradstein (2005) for the paleogene agglutinated foraminifers.

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