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doi:10.2204/iodp.proc.317.208.2014

Results and correlation with the LR04 stack

A plot of δ¹⁸O versus depth shows a cyclic fluctuation between 1.32‰ and 4.11‰, whereas δ¹³C shows a cyclic fluctuation between –1.95‰ and 0.77‰ (Fig. F2). No samples of N. flemingi were found from 10.7 to 63.3 m CSF-A, but good δ¹⁸O and δ¹³C results were obtained from the rest of the section to 550 m CSF-A at intervals of ~1.5 m. The average sedimentation rate within the upper 550 m is estimated as 22 cm/1000 y (see the “Site U1352” chapter [Expedition 317 Scientists, 2011]). As a result, 1.5 m represents ~7000 y, and we are therefore confident that we can recognize δ¹⁸O and δ¹³C fluctuations with cycle periods exceeding ~14,000 y.

Results from coring (see the “Site U1352” chapter [Expedition 317 Scientists, 2011]) suggested that an unconformity lies somewhere between 491.74 and 525.34 m CSF-F, with a hiatus from 1.8 to 2.7 Ma. We use this correlation, together with the seven Pleistocene nannofossil datum levels that fall within the measured section (Table T3; see also the “Site U1352” chapter [Expedition 317 Scientists, 2011]), to correlate the δ¹⁸O record (Fig. F3A) to the global benthic foraminiferal δ¹⁸O LR04 stack of Lisiecki and Raymo (2005) (Fig. F3B) and to plot the Expedition 317 δ¹⁸O record versus age (Fig. F3C). Ultimately, we recognize all of the marine isotope stages (MIS) of the LR04 stack (Lisiecki and Raymo, 2005) except for MIS 3 and 4, which are expected to lie within the interval between 10.7 and 63.3 m CSF-A where N. flemingi was absent (Fig. F3C).

A depth-age curve (age model), based on the isotopic correlations, was generated using AnalySeries 2.0.4.3 software (Fig. F4) and indicates that the average sedimentation rate in the upper ~500 m of Hole U1352B is ~28 cm/1000 y. However, sedimentation rates fluctuate; the maximum rate is ~60 cm/1000 y, and the minimum is <10 cm/1000 y.

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