Species-specific benthic foraminifera stable carbon isotope ratio offset of ODP Site 145-883

Here we present stable oxygen and carbon isotope measurements of C. wuellerstorfi and U. peregrina in discrete samples from ODP site 883. Samples were freeze dried, weighed, soaked in water for 24 hours to disaggregate, and wet sieved using a 150 μm mesh sieve. Samples were then dried at 40°C. Select genera and species were picked and comprehensively counted from the 150–355 μm fraction. 106 samples were run in duplicate or better. Specimens selected for isotopic analysis were cleaned with 70 μL ethanol and sonicated for 30 seconds. Ethanol was drawn off with a pipette, and specimens were dried overnight at room temperature. Cibicidoides mundulus was used in 2 samples where Cibicidoides wuellerstorfi was not sufficiently abundant to provide a good signal for mass spectrometry. Isotope ratios were quantified at the Brown University stable isotope facility with a Finnigan Mat 252 with Carbonate Kiel III autosampler, in which individual samples were reacted with 70°C H3PO4. Cibicidoides δ18O values were adjusted by +0.64‰ to Uvigerina values. Cibicidoides mundulus isotopic values were taken as equivalent to C. wuellerstorfi. Only C. wuellerstrofi values should be used for analysis of stable carbon isotope data.