This data set contains the measured stable isotope data on 106 samples of Cibicidoides spp. (C. pachyderma, C. robertsonianus and Lobatula lobatula) and 27 samples on Uvigerina mediterranea from core GeoB9512-5. The samples were obtained from working/archive halves at the GeoB Core Collection at the MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany. 10 cc of sediment was collected every 2.5 cm, and the samples were (1) washed with deionized water through a 63 µm sieve, then (2) dried for less than 24 hours at 45°C, and (3) dry sieved through 63 µm, 125 µm, 150 µm, and 250 µm. Finally, the washed sediment with a size >150 µm was used to retrieve around 8 specimens of each species per sample when present. d13C of Cibicidoides robertsonianus was corrected by a species-specific offset calculated contrasting the present data with the published data in https://doi.org/10.1594/PANGAEA.894312. Samples with corrected values are indicated in the data set.