Stable oxygen isotope measurements were performed on cores RECORD23, MD90-912 and KET82-21, on 10-20 hand-picked and well-preserved (clean and intact) specimens of the planktonic foraminifera G. bulloides (fraction 250-315 µm). Samples were analysed at the State Key Laboratory of Marine Geology (Tongji University) using a Finnigan MAT-253 mass spectrometer (Cheng et al., 2005). Shell oxygen isotope values are expressed in conventional delta notation () relative to the isotopic ratio of the carbon dioxide gas derived from the Vienna Pee Dee Belemnite (VPDB) standard. Ratios are reported in ‰. VPDB is defined with respect to the NBS 19 (δ18O of -2.20 ‰ VPDB), limestone standard. The mean external reproducibility was checked by replicate analyses of laboratory standards and is better than ±0.14‰ (±2σ) for δ18O.