Sea-level estimates during the last deglaciation based on δ 18O and accelerator mass spectrometry 14C ages measured in Globigerina bulloides

Coupled measurements of δ ¹⁸O and accelerator mass spectrometry (AMS) ¹⁴C in a particular species of planktonic foraminifera may be used to calculate sea-level estimates for the last deglaciation. Of critical importance for this type of study is a knowledge of the seasonality of foraminiferal growth, which can be provided by δ ¹⁸O measurements of modern shells (core tops, plankton tows). Isotopic (δ ¹⁸O, AMS- ¹⁴C dating) and faunal records (transfer function sea surface temperature) were obtained from two cores in the North Atlantic at about 37°N. The locations were chosen to obtain high sedimentation rate records removed from the major ice-melt discharge areas of the last deglaciation. Based upon Globigerina bulloides data, four δ ¹⁸O-based sea-level estimates were calculated: -67 ± 7 m at 12,200 yr B.P. and -24 ± 8 m at about 8200 yr B.P. for core SU 81-18; -83 ± 10 m at 12,200 yr B.P. and -13 ± 11 m at about 8500 yr B.P. for core SU 81-14. Using a second working hypothesis concerning the seasonability of G. bulloides growth, it is suggested that the sea-level rose by about 40 m during the millennium which followed 14,500 yr B.P.