Fig. 3.

Assessment of the impact of burial-induced isotope re-equilibration on the benthic foraminifera O isotope record. a Five-point moving average of the burial depths at the DSDP–ODP–IODP sites from which the most comprehensive O isotope compilation is principally derived⁹. The red line indicates the depth profile used for the numerical simulations. The corresponding sediment temperatures are indicated in purple. b, c The benthic foraminifera O isotope compilation from Friedrich et al.⁹ (grey) is shown with the results from numerical simulations run with a diffusion activation energy of 90 kJ mol⁻¹ and a range of geothermal gradients in b, and with a geothermal gradient of 50 °C km⁻¹ and a range of diffusion activation energies in c. These curves represent the present-day O isotope compositions of benthic foraminifera tests that underwent diffusion-controlled O isotope re-equilibration during burial, assuming an ice-free ocean (δ ¹⁸O = −1‰ VSMOW) and a temperature of 3.5 °C at the water–sediment interface