Benthic foraminifera assemblage counts and diagenetic characteristics from IODP Site 323-U1339

Benthic foraminifera were quantitatively identified (>150µm size fraction) in 158 samples from IODP site U1339 on the Umnak Plateau, southeastern Bering Sea collected by Expedition 323 Scientists in 2009. Benthic foraminiferal assemblages and diagenetic characteristics data were collected to reconstruct methane seepage and benthic oxygenation in the Bering Sea across Marine Isotope Stages 7 to 12. Approximately 20 cc of sediment per 1 cm sample was freeze-dried, weighed, and washed over a 63 µm sieve with distilled water. The sand fraction was oven-dried at 50°C and all benthic foraminifera >150 µm were picked under a stereomicroscope. Samples yielding >300 individuals were split with a microsplitter to obtain a representative aliquot of ~250–300 specimens; samples with fewer than 300 individuals were picked in their entirety. Presence of authigenic carbonate was determined for all samples using a stereomicroscope and recorded as a simple yes for presence and no for absence. For multivariate analysis, counts were converted to proportional abundances and a principal coordinates analysis (PCO) conducted. The site scores of the first three PCO axes are reported.